Solar Air Dryers in Food Proceesing

5/11/2018 Solar Air Dryers in Food Proceesing

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SOLAR FOOD PROCESSINGTECHNOLOGY

Dr. M. Ramakrishna Rao

Published By:SOCIETY FOR ENERGY, ENVIRONMENT &DEVELOPMENT (SEED)Plot No.81,'golden Residency'Road No.7, Jubilee Hills, Hyderabad-500 033Phones (040) 2 3 6 0 8 8 9 2 / 2 3 5 4 6 0 3 6 ; Fax (040) 23547137

Email: [email protected] Website: www.seedngo.com
mailto:[email protected]://www.seedngo.com/http://www.seedngo.com/mailto:[email protected]


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PREFACE

The title and contents of this booklet isunconventional and unfamiliar as it explains thescientific innovations of Solar Cabinet Dryer, itsapplications and the results to out reach the Society fortheir benefits. But the author is not only academician buta firm believer that scientific innovations should reachthe Society for economic benefits. This led to myjourney along with our esteemed colleague Prof. P.N.Murthy to the task of transferring the technology to ruralfarmers, women and youth to get their agri - horticulturalproduce as value added products thereby enhancing theirincome for the processed products and create jobs oremployment potential. Hence our innovativetechnology has taken many turns and fmally we couldreach our rural entrepreneurs through micro enterprises.In the value addition chain for products, our effortsstarted from processing of fruits and vegetables, spicesand other food products and reached up to the consumerthrough the rural micro enterprises. The value additionof the high quality products of unique nature andprocessing with zero energy cost of green energy are thehighlights of the book. So the book is aimed to satisfyfood scientists and students with regards to thetechnological advancement of solar dryer technologyand food processing discipline. Finally this book coversmulti faceted topics to facilitate the technology flows torural women and youth for better life and well being.

Dr.M. Ramakrishna Rao


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Acknowledgement

I am grateful to the management headed by Prof. P.Rama Rao, Chairman and Prof. P.N. Murthy, President ofSociety for Energy, Environment & Development(SEED) for encouraging me to write a book on 'SolarFood Processing Technology' which is novel and uniquetechnology in food processing area. My sincere thanksare to Sri P.V. Suryaprakash Rao, an eminent FoodTechnologist of the country and Director ofPriya Foodsfor going through the manuscript, editing it carefully andby making very useful suggestions to improve the qualityofthe text. I am very thankful to my esteemed colleagueto Dr. G. Sarojini, Former Senior Scientist of AcharyaN.G. Ranga University who has been working with mefrom the very beginning of the introduction of this newtechnology in your laboratory. My thanks are due to mycolleagues Ms. V. Veena, Ms. B.R.Madhavi, Ms.B.C.Basamma and Ms. T. Rajini who associated with me inproviding a lot of scientific data and information on thesolar food processing products and Sri. Y.Y.Rao fortyping the manuscript and bringing the publication ofthis booklet.

We thank the SEED division of Dept. of ScienceTechnology, Govt. of India for supporting with a grantunder core support scheme for the publication of thisbooklet.

Prof. M. Ramakrishna RaoHon. Gen. Secretary


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CONTENTS

S.No. Topic P. Nos.1. Chapter-I: Solar Energy 5-82. Chapter - II: Current status ofsolar dryer technology 9-123. Chapter - III : Innovative solar cabinetdryer Technology 13 - 274. Chapter - IV : Simulated shade drying 28- 33

5. Chapter- V : Solar food processingTechnologies for rural areas 34-466. Chapter - VI: Solar dried fruits & vegetable 47-products

Author's Resume 80- 81


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CHAPTER-lSOLAR ENERGY

IntroductionThe energy scenano m India is complex posmg manyproblems. Every State is passing through energy crisis at some

point of time every year. The demand for energy is increasing dayby day with the increase of Industrialization and the growingpopulation. It is anticipated that the deficit between demand andsupply is going to be 10% - 15% every year in the next 10 years, inspite of the low per capita consumption of electricity which isaround 700 kwh, whereas this figure is around 10,000 kwh indeveloped countries like USA, UK and CANADA. Ifwe have toachieve an increase of even 500 kwh per capita consumption in thenext 10 years period, we need to double the installed capacity ofour power generation. Various strategies have been adopted tomeet the situation, such as, energy conservation, achieving highestefficiency in power generation and utilization, use and applicationof renewable energy technologies, etc. One ofthe ways of bridgingthis deficit gap is the application of renewable energysources/technologies in various sectors. Today's renewable energysources include wind, water, oceans, solar radiation (Thermal andphotovoltaic), wood, cogeneration, bio gas and biomass. Many ofthese new sources are already commercialized in the world marketand the Indian Market is also catching up. While launching India'snational action plan on climate change, Prime Minister, Dr.


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Manmohan Singh stated "The sun occupies center-stage, as itshould, being literally the original source of all energy. We willpool our scientific, technical and managerial talents, withsufficient financial resources, to develop solar energy as a sourceof abundant energy to power our economy and to transform thelives of our people. Itis heartening that these new technologies arebecoming more reliable and competitive. The industry is poisedfor rapid growth in the years ahead". Presently available SolarEnergy technologies have their ability to harness the energy fromthe sun. Solar energy has been utilized for several applications,such as, hot water systems, power generation, drying systems andcooking. Ithas a bright future and we, therefore, look forward tomany magnificent and innovative approaches in the comingdecades.Solar Energy-Global RadiationIn our galaxy, the sun is a medium-sized star. The sun is aglowing fire ball consisting of hot gaseous matter, notablyhydrogen and helium. The sun radiates 53 million watts of energyper square meter of its surface. The sun converts 660 million tonsof mass into energy every second. The earth receives 170 x 1012Kilowatts (or 170,000 million megawatts) from the sun.This is 15,000 to 20,000 times the world's present totalconsumption of energy.

All the solar radiation emitted in the Earth's direction,however, does not reach the surface of the earth, due to theabsorption and scattering processes in the earth's atmosphere,which reduce the solar radiation reaching the earth's surface. Thespectral distribution of solar radiation on the earth is greatlyinfluenced by location, climate and atmospheric conditions. Thesum of direct, diffuse and ground reflected radiation arriving at the


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surface is called global or total solar radiation on horizontalsurface (Fig. 1.1).

Zenith

Aerosols }Water vapor SpectralClouds scatteringOzone and(etc) absorption

Atmosphere

Dittuse Direct(scattered) beam

I radiation radiationGloba" radiation . . . . J

FIGURE 1 : UNDERSTANDING SEASONAL ATMOSPHERIC VARIATIONS

F ig ure .1 : S OL A R S P E C TR A L IN T E N S IT Y FO R A IR M A S S O N E A N D T W O

Air Mass, m, is the path length of radiation through theatmosphere, considering the vertical path at Sea level as unity.Thus at sea level, m =1when the sun is at the zenith (i.e., directlyoverhead), and m = 2 for a zenith angle (6z' the angle subtended bythe zenith and the line of sight to the sun) of 60. For all but veryhigh zenith angles (m> 3, where the earth's curvature becomessignificant).Urban air pollution caused by dust, aerosols and presence of watervapor, clouds, ozone, etc., limit the solar radiation at differentlocations on the earth. Air pollution reduces the direct solarradiation on the earth's surface due to scattering and absorptionwhen compared with global radiation.Accurate information is important for designing solar energysystems. Available solar radiation data gives the values of energyper unit area at select locations.


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Table-I: Units and Conversion Factors1 kWh =1000 Watts (power)

MULTIPLY BY TO OBTAINCalories 0.004 BTUWatts 3.413 BTUIHr.

Watts/sq.m 0.317 BTU/ (Hr.)(sq. ft.)Langleys 3.687 BTU/(sq.ft)

Calories/( cm)( sec) 13.272 BTU/ (Hr.) (sq. ft.)Langleys/minute 221.2 B TU/ (Hr.)/ (sq. ft.)

Calories/Hr/sq.cm/? C 2.048 B TU/ (Hr.)/ (sq. ft.)/( .F)kWh 3600 KilojouleskWh 860 Kilocalories (Kcal)kWh 3412 British Thermal Unit (BTU)kWh 1.34 Horsepower- Hours

Kilojoules 0.278 Watt-hoursKilocalories 1.16 Watt-hours

British Thermal Unit 0.293 Watt-hoursHorsepower-hours 0.746 KWh

Distribution of Solar Energy in IndiaThe following figure: 1.2 indicates the average global solaradiation levels in different parts of India are illustrated. They aremade into five zones; Eastern region has 3.5 to 4.0 kwh/m'Northern, Himalayan region has 4.0 to 4.6 kwh/m', Southern andmiddle zone has 5.2to 5.8 kwh/m", Western zone 5.8 to 6.3 kwh/m'.More than 80% of the country received solar energy above 5.2kwh/m', on horizontal surface. The annual global radiation isoinsolation lines for different locations are also shown in the Fig.l.2They range from 1,600 to 2,100 hours (sunshine hours) annually.


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Zonal Distribution of Global Solarradiation

FIGURE 2, DISTRIBUTION OF GLOBAL SOLAR RADIATION


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CHAPTER-IICURRENT STATUS OF SOLAR DRYER

TECHNOLOGYIntroduction

In 1970's the Solar Energy Programme was initiated by Dr.ArcotRamachandran, the then Secretary, Department of Scienceand Technology (DST), Government oflndia and later nurtured byDr. Mahesh Dayal, the then Secretary ofMNES, now Ministry ofNew and Renewable Energy (MNRE). In order to popularize andpromote the RenewableEnergy Technologies (RETs), a number ofdemonstrations and extension programs were implemented in 80'sin Solar Hot Water Systems, Solar Drying Systems, SolarPhotovoltaic Systems, Solar Cookers etc., under 100% subsidyscheme of MNES. Due to lack of experience and immaturetechnologies employed by entrepreneurs in solar field, SolarEnergy Programmes experienced rough weather during that periodand led to a review of technologies employed, materials used andengineering practices adopted in Solar Energy Programmes. Insubsequent periods, the drawbacks were corrected and theequipment improved to standard quality.Air Collector System

In solar drying, the air collector system, which is called a rooftop system, which belongs to indirect drying systems, wasdeveloped and commercialized byPalaniappan (1) of PlantersEnergy Networks, Madurai, Tamilnadu. Eventhough theefficiency of the system is low; this technology was successfully


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applied to drying tea, pulses, fish, and other industrial applicationsduring the last two decades.

N.S. Rathore(2) designed and developed another simpleefficient roof integrated convective type solar dryer for drying ofDibasic Calcium phosphate atMis. Phosphate Zinc Co., from 40%to 10% moisture content. The system consists of solar aircollector, with area of 150m2 ,rotary kiln above of 10HP andexhaust fan of2 KW capacity.

Ajay Chandak (3), while popularizing the Schaffler ParabolicConcentrators for solar community cooking, he also developed thesolar dryer with turbo ventilators coupled with commonly usedsolar air collector panel system.In the place of exhaust fans, heintroduced a novel turbo-ventilators for generating draught usingwind energy. This is also an indirect solar air dryer.Forced Circulation dryer

In 2000, the innovative high efficiency cabinet dryer wasdesigned and developed by a team led by Prof. M. RamakrishnaRao of Society for Energy, Environment &Development (SEED),Hyderabad, Andhra Pradesh with forced circulation, using a noveltechnique of solar photovoltaic energy. This belongs to the type'Direct Solar Cabinet Dryer'. This innovation opened up a newfield of applications on a commercial scale, which is known asSolar Food Processing Technology on Micro level and is alsopatented (Patent no. 211911)Solar tunnel dryer

Besides these two technologies, Solar Tunnel Dryerdeveloped by Dr. N.S. Rothore of MPUT Univ., Udaipur as alsoSolar dryer by SPRIT, Anand, and a tent type solar dryer byBARC, Mumbai as demonstration models.


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Indirect solar dryerThe important functional subsystems in this dryer consists of

solar air collector, made up of two rectangular corrugated zinccoated mild steel sheets that are joined together and welded on thetwo long sides of the collector. This facilitates formation of airpassage channels in between these sheets. Of the other two sides,one is connected to air inlet through electric blower and the other isair outlet-connected to the drying chamber. Since black colorabsorbs the radiation to a maximum level, the top surface of thisthin corrugated rectangular plate is coated either by a black paint ora selective coating to absorb the solar radiation incident on it. Thetop surface of the absorbing plate gets heated up due to theincidence of the solar radiation and the heat transfer takes placebetween the black absorbing surface and the air passing in thechannels underneath the surface sheet. In order to reduce thethermal losses and retain the maximum temperature of theabsorbing plate, the entire rectangular air collector box is coveredwith a transparent glass on the top and insulating glass wool in thebottom. The total assembly is called the Solar Collector. Anumberof solar collectors can be configured either in parallel or series,depending on the volume of the hot air required or the highertemperature requirement ofthe system.The operation of the system comprises the drawing ofambient air into the collectors and forcing the air to pass throughthe passage channels in the collectors. Thus, the air gets heated to ahigher temperature from the absorbing plates and enters into thedrying chamber, where the products are to be dried.ApplicationsThese systems are very useful in supplying preheated air tothe high temperature flu gas generator when large volumes ofproduct are to be dried at elevated temperature in the dryingchamber and in retrofit systems to supplement partially the


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consumption of fossil fuel with solar energy. In India, they are usedfor drying of cereals, pulses, tea, fish and fruits. The conventionalpractice is to dry the pulses with hot air produced by furnace oil ordiesel oil. The solar air collector system can be interfaced withexisting system in the industry as retrofit system. The solar hot airvent thus store and supplements supply of preheated air to the pulsedrying, saving thereby fossil fuels and reducing air pollutionreleased into the atmosphere.

It is not advisable to apply the technology to seasonalagricultural crops. The solar drying plant should work for 300 daysin a year so that the economics of costing would work out to befavorable.Limitations ofindirect solar technology

Since it is an indirect solar collector, the efficiency ofcollector and the temperatures attained in the drying chamber arelow. Further, the conventional electrical energy used for theblowers to force the air into the collector system to deliver hot air todrying chamber with a constant high speed is responsible forcarbon emission and pollution of the atmosphere. The constanthigh speed blowers consume more energy than what the systemrequires for operation.Direct solar cabinet dryersThe Other types of dryers are direct dryers where solar radiation isdirectly incident into the cabinet. They are box type, tent type orcabinet type. They operate on the principle of natural convectiveairflow in drying chamber. They are called natural convectivedryers. In these dryers, the ambient air enters through the inletholes in the bottom of the cabinet and the moisturized hot airexhausts through ventilators located at the top of the cabinet. Thesolar radiation is incident through transparent glass or plasticsheet. This causes the temperature of air inside the cabinet to be


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higher than ambient air. Green house effect also plays an importantrole here. But the great disadvantages are that the air circulation incabinet is by natural convective air and hence the removal of themoisture in the product is very slow and ineffective. Secondly, theinlet and outlet passage holes are designed and arranged for normalspeed of air in the atmosphere. But in practice, the rate of moistureevolution from the wet product is variable, depending on thevariation of the solar radiation in a day and also the seasonalvariation. The nature of moisture evacuation mechanism underthese constraints, determines the output of exhaust air in thecabinet. This results in variation of output air to atmosphere fromthe ventilators, from the output initially designed. The break downin the balancing of air input to air output in the cabinet frequentlyleads to condensation of moisture on the inside surface of glass,preventing further penetration of solar radiation into the cabinetand raises relative humidity level in the chamber. If this persists, atthe end of the day, the drying product will be subjected to spoilagedue to fungus and mold formation because of the higher humidityin the chamber. So the natural convective cabinet dryers were notencouraged in the country but remained as an exhibit andexperimental models.


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CHAPTER - IIIINNOVATIVE SOLAR CABINET DRYERTECHNOLOGY

BackgroundIn the evolution of drying technology, solar scientists haveestablished the fact that the forced circulation of air by arranging

blowers in drying cabinets, results in high efficient drying system.But no attention was paid until now to the idea of designing thesmall solar cabinet dryer with suitably rated electrical fansaccording to the size of the dryer with appropriate configurationand distribution offans. Probably it was thought that small cabinetdryers would not have great demand. This resulted in slowprogress in research in this direction.

With this backdrop, a groundbreaking innovative solarcabinet dryer and appropriate technology were designed anddeveloped in 1998 by a team under the leadership Prof. M.Ramakrishna Rao. This dryer has the unique feature of forcedcirculation of air with solar fans, run by electricity generated bysolar photovoltaic method. This dryer technology is patented andcommercialized, leading to solar food processing technology forthe first time in India.The direct solar cabinet dryerThe cabinet dryers with forced circulation are highly efficientsystems, since the thermal energy is at its maximum due to directincidence of solar radiation into the cabinet through glass window.The criteria for sustainable and reliable solar drying technologyare given in the following flow chart.


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CRITERIA FORRELIABLE & SUSTAINABLE PROCESS CHAIN

ConcepttDesigntMaterialtComponentstFabricationtTestingt

Evaluation of PerformancetApplicationtCost Economics

Origin of new technologyIn 1996 one young manufacturer approached the

author with a suggestion that a solar dryer could be usefulif designed for drying of Gum karaya, an edible gum, aforest produce that is tapped by tribal families from'Tapasive' tree in the forests of Andhra Pradesh.Nearly10,OOOfamilies live by selling this product. Theeffective drying determines the quality of gum. Heemphasized that this type of dryer was very much


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required by Tribal Development Corporation of AndhraPradesh for drying of Gum Karaya. After a year or so, theUNDP funded the project with a small grant underschemes for the welfare of Tribal people in theapplication of green energy technology. After studyingthe problem, the project was formulated to help the tribalfamilies to enhance their income generation capacitythrough their occupational activities with theintervention of Science and Technology. This projectwas sanctioned and funded and was completed in 1998.

The solar powered solar air dryers described in thisbook is new and innovative technology through blendingsolar thermal and solar photovoltaic technologies. Thisis designed and developed by R&D team headed byProf. M. Ramakrishna Rao of Society for Energy,Environment & Development (SEED) with the grantssanctioned by UNDP. DST& REPSO funded for thedevelopment of commercial version of dryer and itsapplication to processing of Mango bars, for the firsttime. This technology is patented (Patent No. 211911).Working principle ofinnovative technology

The integration of solar thermal energy and solarphotovoltaic technologies in the design and developmentof solar cabinet dryer has resulted in a new andinnovative technology related to drying process, which iscalled Solar Powered Solar Air Dryer.


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Solar radiation, incident on the transparent glasswindow, located on the top of cabinet dryer, passes intothe closed cabinet and heats up ambient air entered frombottom air inlet louvers of the cabinet.

The heat energy of solar radiation is trapped in thecabinet and heats up the air molecules. The result is thatthe wave length of solar radiation shifts from visibleregion to infrared region (IR). The top cover glass doesnot allow the hot air (IR) to escape through the glassfrom the cabinet. This causes the green house effect.The hot air passes through the wet products in the traysfor drying, carries the moisture air from the product to thetop space below the glass. The temperature inside theclosed cabinet will rise to 15 - 30C above the ambient,reaching finally the cabinet temperature to 50- 70C.

The hot air, with moisture content in the cabinet, isexhausted continuously by solar fan operated by the solarphoto electric power. This phenomena introduced theforced circulation in the cabinet , resulting in highefficiency of the dryer. The source of thermal energyrequired for drying and the supply of photovoltaic powerare from the same source of solar radiation during thesame day. A close synchronization is achieved inregulating and controlling the drying process betweenevaporation of moisture from the product and the rate ofspeed of exhaust fan. This regulates the solar power tothe fan throughout the drying process with variable solarintensity during the day.


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Design approachThe design approach was based on the followingcriteria:-i) Solar dryer should be compact and easily

transportable from field to village and viceversa. It should be based on green energy andeco - friendly energy.

ii) Dryer should be highly efficient cabinet typedryer with forced circulation (with powergenerated by solarphotovoltaic energy)

iii) The forest produce such as gum karaya shouldbe of high quality and high yield products andshould fetch good price for the value addeddried product.

The design was completed and was tested with forestproduce. The dryer was then demonstrated in tribalareas of Bhadrachalam where tribal youth experimentedin drying the gum karaya in the solar dryer. They highlyappreciated the results.Now let us look into the illustrations of Solar Dryer

SDM - SO.-Integration Mechanism

Figure 3.1: Solar dryer integration mechanism


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Description: A closed cabinet solar dryer is meant especially fordehydration process of agri-horticultural products such as fruits,vegetables, spices, herbs and marine foods as well as processedfood products as illustrated in fig.3 .1. It has a transparent glazingglass (2) through which solar radiation passes into the chamber (1)and the same source of radiation simultaneously incident on solarphotovoltaic panels (6) of suitable wattage and voltage to generatethe current to drive the solar fans (5) situated on the back wall ofchamber to exhaust moisture laden air "0" to atmosphere in forcedcirculation mode. The chamber is mounted on 4 or more casterwheels (9) and oriented to in the direction of South to about 20tiltfor maximum solar energy collection. The Electrical back up isprovided to meet the exigency of over cast in the sky, or cloudyweather etc. (10).The Greenhouse effect

Sunlight can easily go through the glass of a greenhouse andheat the floor and air inside. But only a small part of the stored heatwill be radiated back outside because the glass captures themajority of the heat radiation. It resembles a trap: The sun's heatcan get in, but it cannot get out again.

The layers of air in the Earth's atmosphere also act like agreenhouse roof. They keep the heat of the sun locked in andguarantee us an average temperature of 14C. If the Earth did nothave a layer of air, the average temperature on its surface would beminus 31C. In the atmosphere, the carbon dioxide (C02) forms avery effective shield that keeps heat from radiating out into space.Carbon dioxide is formed through the combustion of gasoline,diesel oil, natural gas, lignite, coal, and wood. The increasingworldwide combustion of these fuels leads to increased levels ofCO2 which in turn leads to the heating of the Earth's atmosphere.This is the greenhouse effect.


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3.2: The Green House EffectGreenhouse effect phenomenonLet us examine the second diagram where greenhouse effect isdescribed. Most greenhouses look like a small glass house whereplants are grown, especially in the winter. The green houses workby trapping heat from the sun. The glass panels of the green houseallow the heat to enter and do not allow the same to exit asmentioned above. This is called the greenhouse effect. Thiscauses the green house to be heated up, much like the air in a carparked in sunlight. The different parts of cabinet dryer aredescribed as is done in the previous figure. Mainly, the solarradiation, reflected from the glass panel, inside the cabinet isshown in wave natured one which indicates the reflected radiationand which causes higher temperature inside the cabinet.

Solar Dryer - Green House Effect-- - - ----- ----

-~ .Figure 3.3: Solar Dryer - Green House Effect

SOLAR DRYER INTEGRATION MECHANISM


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The higher temperature in thermometer located in stand (8) isrecorded due to the entrapment of solar radiation inside thechamber. In the figure 3.2 Infrared Radiation (I.R) of green houseeffect is caused by of non-transparency of top glass (2) to I. R. Thesolar panel (6) generating D.C. current, mounted on top of thedrying chamber which drives the respective solar fans (5) locatedon the back wall ofthe chamber.Solar Fans- novel forced circulation technique

Let us examine the advantages of forced circulation in dryersof cabinet type and also the question of what should be the type ofconfiguration pattern inthe dryer and the availability of electricalenergy to drive the fans. We then turned our attention to the solarphotovoltaic technology for possible solutions to these problems.The advantages ofthis technology are:-i) Clean, inexhaustible, non-polluting and green energy

utilization.ii) Photovoltaic energy is variable depending on intensity of

solar radiation and the range of solar panels withdifferent wattages and voltages are available.

iii) In situ electrical energy can be generated with panels todrive the fans in the dryer.

iv) Synchronization between the speed of solar fans andmoisture level ofthe product in the dryer to exhaust air toatmosphere is easily achievable as same solar radiation isincident on solar panel as well as solar transparentwindow of the dryer.

v) The electrical energy is conserved with variable voltageof fans instead of fixed voltage fans of ordinary type.

vi) The solar fans can be configured in distributed pattern inthe exhaust mode for efficient exhaustion of air in thedrying process.


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All these features are incorporated with proper designs and highlyrated values for efficient performance of our dryer.Main mechanical design features of the Dryera) The selection of size of the dryer

b) Arrangement of traysc) Location of solar fansd) Electrical Backup (Stand by)e) Orientation of Dryerf) Selection of materials for constructionThe aim of designing the solar dryer is to provide assistance to

people in the villages to tap local horticultural produce and to turnit into value-added products. The dryer design should accordinglybe convenient and suitable for their needs.Size of the Dryer: This is guided by the operation location andthis convenience ofthe rural users. The dryer should be operated inthe village or preferably in the field where the agri-horticulturalproduce is processed. Hence, it should be transportable to the fieldwhenever it is required. The mode of transport should be suitableto local availability. Accordingly, the size of the commercial dryerwas conceived to be 1.85mx 1.23mx 1.38m(6ftx4ft x4 ~ft).

The solar energy collected by this window is sufficient toevaporate 15 kg of water from the wet produce of 50 kg ofmaximum weight.Arrangement of Trays: The tray space needed is spread over areaof3.6 sqmts in the dryer capable of bearing a mass of 14 kg persqmts. The total area of trays for drying the product is dividedinto two rows, each having 6 trays of3 .35m L x 1.21 m B x 0.60 mH (11' Lx 4'b x 2' h). It may be closed trays for liquids or solids orsemi liquids or mesh trays for shredded pieces or individual leafymaterials.


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Solar Fans: Solar D.C fans are arranged in exhaust mode indecentralized manner in 3 segments at the top of the cabinet forefficient operation. They are driven by the solar power, generatedby the solar photovoltaic panels of suitable rating.Construction material: Solar energy devices are equipmentnewly developed from emergent technologies and are moreexpensive because oflow volume of production. To counteract thehigh price, low cost materials for construction are advocated /used. The result is that the equipment is short lived and failure rateis high. This approach has limited the popularization of solarenergy applications during the initial stages of introduction ofevery new solar technology. Itis the reliability and the durabilityof equipment that is essential for sustainable technology asmentioned earlier.This aspect is considered well from the beginning in the case ofthenew solar dryer. The materials used for construction of cabinet arenon-corrosive S.S trays of 304 stainless steel and hardware ofstainless steel and brass. This is also protected by a coating suitableto elevated temperature. Aluminum was avoided as it issusceptible to corrosion in high humid environment.Loading capacity of dryerIn the drying process, we already learnt that air circulation isessential. Another factor is the spreading density of the wetproduce/ product in the tray. All of us know that the depth of theproduct to be dried should be as low as possible for quick drying.In other words, the product should be spread as a single layer ofoptimum thickness depending on the density of the material. Forexample, if we wish to dry to zero moisture a material like Maidaflour for ready made mix ofGulabjamun, we can load the dryer at50 kg for a single load and it will take 4 hrs.to bring the moisture,say from 4% to 0%. Similarly, we can load 4 kg of curry leaves in a


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single load to dry them to a permissible limit of moisture from 63%t04% in 6 hours. The drying time depends on the moisture contentin the product. The total yield of the product is the sum of finalmoisture content and00200riginai weight (excluding moisture) ofthe product. The yield should not be confused with final moisturecontent of the product.

The time taken for drying of the product with initial moistureto final moisture depends on the state of the product like liquid orsemi liquid, powder, or small pieces etc., (volume per unit area)spreading density in the dryer and nature of the moistureevaporation mechanism of a particular product. It is always betterto choose these parameters in such way that the drying process isgenerally completed in one day. This can be done with initialcalibration prior experimentation. In case the drying process is tobe continued over subsequent days, it does not affect the product asit is pretreated with chemicals and subjected to blanching. Most ofthe moisture is thrown out initially during the first day drying. It isalways better to have larger surface area of the product for a givenquantity of the product by way of cutting into small pieces or athinner layer ofliquid or semi liquid.

The loading of the wet product must be done in the earlymorning before the sun rises so that longer sunny hours areavailable to the drying process. To establish the parametersmentioned above, a trial run is to be conducted before the full loadof dryer is charged.Orientation of Solar Dryer: The dryer is oriented to south with atilt angle of20 degreesElectrical backup for exigencies: During non-summer days andexigencies, the solar dryer can operate with temperatures up to 60-70 degrees C, in the absence of sun, by providing the electricalheaters with radiant shields on top of the heater. 220 voltsAC and


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3.6 KW power is provided for the heaters, located at the bottom ofthe cabinet. Thermostat is provided to regulate the temperature inthe dryer at the desired temperature below 89 - 90 degrees C. Thisfacility is to maintain temperature in the dryer in mixed mode ofelectrical operation or in the electrical mode alone.Technical specifications

Loading SolarCapacity Photo ElectricalS.No. Model Capacity Solar Drying Voltaic Backup 220Approx. Window Area(Weight) panel V.A.C

1 SDM-8 8Kg 0.37 sq.m 0.56 sq.m 3.5W 600W2 SDM-50 50Kg 2.23 sq.m 3.6 sq.m 21'W 3.6KW3. SDM-IOO 100Kg 4.46 sq.m 7.2 sq.m 42W 7.2KW

Different 'SEED' Dryer modelsTwo model solar dryers are available in the market.

They are SDM-8, SDM-50& SDM-IOO.


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3.3: Solar Dryer Plant -350 Figure 3.4: Solar Dryer - SDM-50,.

Figure 3.5: Solar Dryer SDM-8 Figure 6.7: Solar Drying of Betel Leaves


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CHAPTER-IVSIMULATED SHADE DRYING

The shade drying is an important process for some fruits,vegetables and herbal products to retain the higher levels ofnutritive values in food processing technology. In this process, thedirect solar radiation is avoided for drying but diffuse radiation isemployed. A device is designed with glass filter to simulate thecondition of shade drying of food products.

This glass filter reduces the V.V. radiation by about 20% andthe total solar radiation intensity by 40% for simulation of shadedrying of special food products. This filter can be provided inconjunction with top glass cover. In shade drying, the diffuse solarradiation, instead of direct radiation, will dry the product andremove the moisture from the product. The diffuse radiation isabout 10 -14% of total solar radiation received on earth.

This is caused due to the scattering of light downwards fromsmall and large molecule particles in the atmosphere (See the V.V.filter in fig. 4.1)

The retention of nutritional factors, such as ~ carotene ingreenleafy vegetables, is observed by scientists in our solar dryer withthe help ofV.V. reduction filter. This phenomenon has drawn theattention of many experts innutritional diets and healthy foodsencouraging them to undertake further studies. Of course, thisdevice enhances the drying time because oflow heat energy supplyto the drying product in the dryer.


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Figure 4.1: U.v. Reduction Glass Blue filter

RETSAMPLE: w"'' ' ' ' ' Q ' ' ' ' ' ' ' ' '' "n~ g.....~9""oENDING 'UVL : -,100 O,nn')

Q _ O O ~

r- - - - - -{I-,eQ~ . _ _ _sc.oro ' \ (r - .4().U- ~ J -120.Q~

Figure 4.2: Spectrum ofU.V.Reduction Filter (Blue Filter)


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V.v. Reduction filter featuresIn addition to the main features of the dryer, a special feature

is provided with V.V reduction glass filter on the top ofthe glasswindow of the dryer in order to simulate the condition of the shadedrying. The shade drying has many advantages in severalapplications, such as drying of leaves of leafy vegetables,vegetables, leaves, roots, stems of medicinal plants and shrubs.They require low intensity solar radiation such as diffusedradiation instead of direct solar radiation to avoid loss of nutrientand health values of food. This requires that the diffused solarradiation should filter the ultra violet radiation in electro- magneticspectrum. Generally in the dehydration process, the temperaturebelow 70C degree is desirable for the product to dry to thepermissible limit of moisture in the product.

After studying the UV and visible spectrum of several glasses,a special glass was standardized which can filter the UV radiationto a low value thereby reducing the transmission of 85% in therange of 300 nm to 400 nm in clear transparent glass to 62% withV.v. reduction filter, that is nearly 23% reduction. In the case ofvisible region, the transmission is reduced from 90% to 27% in theentire visible range with V.V . reduction filter.

These two factors improve the quality of the dehydratedproducts which are sensitive to UV radiation as well as to directsolar radiation. In shade drying scenario, the diffused radiationcontributes less than 20% of the total direct solar radiation thusreducing the dryer temperature. Thus, the glass filter simulates theshade drying conditions ofthe product in the solar cabinet dryer.

Some studies on drying the drum stick leaves withand without UV Reduction filter were conducted by Dr.MehtabBamji at Dangoria Charitable Trust's FoodProcessing Center, at Narsapur in Medak Dist. AP. They


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processed the drumstick leaves powder in solar cabinetdryer which retains 70% of beta carotene of dried leaveswith UV reduction filter whereas only 30% beta caroteneis retained without UV reduction filter.

These findings lead to many applications of filter inmedicinal and herbal plants in Ayurvedic medicinalapplications.

Intensive research is being conducted in manyInstitutions where nutritional values in the solardehydrated products processed in the solar dryer, arestudied. The spectrum curve ofU.V. reduction filter willbe supplied with order.


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CHAPTER-VSOLAR FOOD PROCESSING

TECHNOLOGIES FOR RURAL AREASIndian scenario

India is one of the largest producers of fruits and vegetables.It ranks 5thamong other countries. The percentage of processedfruits and vegetables is however very small. Table 1 gives thefigures compared with other countries.

Table- I: PROCESSING OF FRUITS &VEGETABLES% OF PROCESSEDCOUNTRY FRUITS & VEGETABLES

INDIA


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Table - 2: CURRENT STATUS OF FOODPROCESSING INDUSTRY

Installed capacity 2. 1million tonnes(fruits & vegetables)Estimated processed food(Fruits & Vegetables) 2.2% of the total productionFPO licensed units 5166 unitsCottage industry share 1083 units2015 target 20% increased

The installed capacity of food processmg industries is2.1million tonnes.

It covers RS Beverages (27%), fruit pulps (22.5%), picklespreserves & chutneys (11%), frozen fruits & vegetables (9.36%),Tomato products (8.05%), jams/squashes (7.45%), canned &bottled products (3.69%), fruit juices (3.28%), dehydrated fruits&vegetables (2.22%), fruit juice concentrate, etc., (0.95%), andothers (4.49%).The share of dehydrated fruits and vegetables isonly about 2.2%, i.e., 30,000 tons per annum. The reasons for thisfigure being small are high cost of processing using electricalenergy and that the international standards of cleanliness are notmaintained in traditional open sun drying.Drying methods-Solar dehydration

Dehydration is one of the important methods of preservationof food. The main objective of dehydrating the food stuffs is toprolong their shelf life beyond that of the fresh material. This isachieved by reducing the water activity (aw) of the food to a valuewhich will inhibit the growth and development of pathogens andspoilage causing microorganisms, besides significantly reducingenzyme activity and the rate at which undesirable chemical


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reactions occur. By proper adjustment of activity of water and theuse of appropriate packaging, the shelf life of the food can beextended without the need for refrigerated storage. The removal ofmost of the water from the food reduces the weight to be carriedper unit food value. This can lead to substantial savings in the costsof handling and transporting the dried product as compared withthe fresh foods. The maximum reduction in bulk is attained whenliquid foods are dried to powders, more so when the powder iscompressed into blocks or tablets. On the other hand, little or nochange in volume occurs when solid pieces of food are freezedried. In between these extremes, varying degrees of shrinkageoccur, depending on the nature of food, the method of drying andthe drying conditions adopted.Drying -changes in quality

Drying is the process by which the water activity is controlledby different drying methods. No pretreatment is given to theproduct prior to the process of drying. No chemicals, additives,and preservatives are used in the process of drying the product.Drying can also bring about undesirable changes both in the color,appearance and solubility characteristics. The size and shape ofsolid food pieces change during drying, due to the shrinkagepointed out above. When reconstituted, they may not return totheir original shape and size. Color changes may also occur due tothe removal of water or exposure to high temperatures duringdrying. Again, the color of the reconstituted product may differfrom that of the fresh materiaL The texture of the reconstitutedmaterial may be less acceptable than that ofthe fresh one becauseof changes in structure due to shrinkage and!or excessive exposureto heat. The capacity of dried food pieces to absorb water may belimited contributing to poor texture. In the case of fruit powders, itis usually desirable that they reconstitute rapidly and completely


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in hot or cold liquid, as appropriate. The extent to which thisoccurs depends on the drying method and conditions. Changes inflavour may also occur as result of drying. These may be due to theloss of volatile flavour compounds during drying and/or to thedevelopment of an undesirable cooked flavour because ofexposure to high temperatures. The extent of these adversechanges depends on the drying method. Freeze dried productsgenerally exhibit minimal changes in flavour. Spray drying andother rapid drying methods bring about moderate changes. Dryingtechniques in which the food is exposed to relatively hightemperatures, e.g. drum drying, or cabinet drying which entailrelatively long drying times, are likely to cause important changesin flavour.Changes in nutritional qualityChanges in the nutritional quality of foods may occur as a result ofdrying. Considerable losses of water soluble nutrients may occurduring the preparation of the food prior to dehydration, such ascleaning, peeling, blanching or cooking. Similar losses would beencountered while preparing foods prior to freezing or canning.During the drying operation itself, the loss of water and lipidsoluble nutrients will depend on the drying method andconditions. Exposure of the food to a high temperature at amoisture content intermediate between that of the fresh materialand the dried product is likely to lead to greater losses. Suchconditions should be minimized by careful selection of the dryingmethod and conditions and good control of the drying operation.In general, drying should result in high retention of nutrients withsolar drying in vitamins C and A. Vitamin-C losses in drying areusually somewhat higher than in canning and much higher than infreezing. Vitamin-A losses in drying can be very much higher thanin canning or freezing. Vitamin-B losses in drying are relativelylow, comparable with freezing and lower than in canning.


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Considerable amount of research in recent years on foodprocessed by many modem dehydration technologies has shownthat good organoleptic characteristics reconstitute rapidly.Consequently, they constitute a significant component of the foodmarket.

Dehydration is simultaneous heat-and-mass transferoperation. The necessary sensible and latent heat evaporation, orsublimation, must be supplied to the food, while water vapourmust transfer from that surface to the surrounding atmosphere.The mechanisms whereby heat is transferred to food provide aconvenient way of classifying the many drying methods usedtoday.Different drying methods

On the basis of heat and mass transfer operation systems,there are four categories of drying methods as follows:In group 1heated air is the drying medium. The food is placedina current of hot air. Most of the heat is supplied to the food byconvection from the air. Such methods are also known asconvection drying methods.

In group 2 the food is placed in contact with a heated surface,usually a metal surface. Most of the heat is transferred to the foodby conduction from the hot surface. Such methods are known asconductive or conduction drying methods.

In group 3 the food is exposed to radiant heat, and radiation isthe main mechanism of heat transfer. These methods are alsoknown as radiation drying methods. Open sun drying fits into thiscategory.In group 4 the food is exposed to radiant heat, which istransmitted to the food both by convection and conduction. Solarradiation with forced circulation by exhaust fan belongs to thiscategory. This is a special category with many advantages.


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In addition to these four main categories, the use of microwave anddielectric energy for drying is also in vogue.Hot air drying systems for solids & semi solidsThe equipment includes:1. Kiln drier 2. Cabinet drier 3. Tunnel dryer

6. Fluidized bed drier9. Solar dryer

4. Conveyor drier 5. Bin drier7. Pneumatic drier 8. Rotary drierSolar drying method

The above drying systems have limitations of their own. Thesolar drying technique, especially of cabinet type with forcedcirculation of air, have all the three modes of heat transfer appliedtogether combining, conducting, convective, and radiation drying.This feature introduces a new factor which is intermediatebetween fast drying on industrial scale with electrical drying andnatural open sun drying or natural convective cabinet drying.

The studies on the drying properties of food such as physico-chemical properties, nutritional factors and sensory properties,combined with pretreatments and uses of preservatives for avariety of food products have gained importance in solar foodprocessing techniques.Solar drying vs. open sun drying

Dehydrated food processing is going to be an important areain the coming years for reasons of giving long shelf life to foodstuffs, better handling facility during shipment and providingvariety to the consumers. During the process of dehydration, thewater activity is reduced greatly thereby preventing spoilage offoods by micro-organisms. Good Manufacturing Practices (GMP)are very essential for processing foods both for export as well asfor enhancing their shelf life, meeting the sanitary and phytosanitary standards of the countries importing processed foods. Inorder to achieve this goal, solar drying technology is found to be ahighly viable one.


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DIFFERENCES BETWEEN SOLARDRYING &OPEN SUN DRYING

Solar Air Drying Open sun Drying~orerecentinnovation Traditional methodFast drying Slow Drying

No contamination Problems of contamination

Highly hygienic & very clean Less hygienic and less cleanBest quality products Inferior quality products

Meets GMP requirements May not meet G~PDrying possible on all days including Drying possible only on sunnycloudy and rainy days with electrical daysbackup.Highly acceptable sensory qualities - Poor sensory qualities -

appearance,Attractive appearance, color and texture Poor Color and Texture

Even drying Uneven drying

Highly viable for quality, commercial Not acceptable for exports andcannot attain standards of valueproduction and economically viable added products


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Solar dehydration processed dataFor the last few years, intensive work has been done in drying

fruits, vegetables, green leafy vegetables, forest produce like Gumkaraya and spices etc., in the Solar Powered Dryers. This work wastaken up to see the effectiveness of these dryers in the dehydrationof a variety of products. Dehydration process requirespretreatments, addition of chemicals for superior sensory qualityand shelf-life, fast drying, moisture control, etc.

About 60 productswere dried after pretreatment to gather dataregarding the drying temperatures, drying time, moisture controlto permissible limits and ambient temperatures. The data arepresented in the following table.

DRYING CONDITIONSS.NO PRODUCT Spreading Time Yield(%) Cabinet/ Permissibledensity (Sunny of (Ambient) limits of

kglm2 hours) product Temp. retention(0 C) % o f mo is tu reon wet weight

basisI 2 3 4 6 5 7

FRUIT BARSI Mango Bar 7 16 55 60 12(2 layers) (25)2 Guava Bar 7 16 55 60 12(2 layers) (25)3 Mixed Bar 7 16 55 60 12(2 layers) (25)4 Sapota Bar 7 16 55 60 12(:llayers) (25)5 Khatta- 7 16 55 60 12

MeethaBar (25)I (2 layers)Fig Bar 7 16 40 60 12

6 I (2 layers) (25)No Sugar 7 16 40 60 127 Added Mango (25)bar(2 layers)FRUIT SLICES

8 Apple Slices 9 8 16 50 8(25)9 Mango Slices 9 10 26 59 8(29)10 Sapota Slices 4 8 27 50 8

(25)11 Pineapple 5 20 18 45 8Slices (27)

12 Papaya Slices 9 18 37 42 8(27)13 Grapes 14 25 20 53 4(31)

VEGETABLES14 Potatoes 5.0 4 16 50 5.0


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VEGETABLES14 Potatoes 5.0 4 16 50 5.0(31)15 Donda 5.0 19 30 50 5.0(30)16 Carrot Crush 5.0 10 15 50 5.0

or Mince (31)17 Carrot Slices 4.0 14 15 50 5.0

(31)18 Tomato 5.0 10 10 60 5.0(30)19 Mushrooms 4.0 12 15 50 5.0

(33)20 Bitter gourd 4.0 6 10 50 4.0

Crush or (26)Mince

21 Bittergourd 4.0 8 10 42 4.0Slices (26)

22 Onion 5.0 18 17 50 4.0(24)23 RagiMalt 3.5 4 75 50 4.0(33)24 Raw Mango 9.0 16 22 50 4.0

(Amchur) (28)25 Desiccated 3 5 30 50 4.0

Coconut (29)26 Cashew Nut 3 8 97 49 4(30)

GREEN LEAFY VEGETABLES27 Curry leaves 6.0 8 35 55 4.0(30)28 Spinach leaves 5.0 15 8 55 4.0(30)29 Fenugreek 5.0 6 13 50 4.0

leaves (30)30 Tamarind 5.0 12 11 55 4.0

leaves Tender (30)31 Gogu leaves 5.0 15 16 55 4.0(30)32 Mint leaves 5.0 5 17 55 4.0(28)


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33 Drumstick 5.0 6 15 55leaves (29)34 Coriander 5.0 6 12 50leaves (28)35 Wheat Grass 5 55powder (29)S PIC E S & CONDIMENTS I36 Mango Ginger 5.0 12 16 50

(31)37 Garlic Powder 3 4 33 55(29)38 Red Chillies 5.0 48 17 50(Big Variety) (30)39 Red Chillies 4.0 30 26 59(Small (25)Variety)40 Pickle Red 4 24 25 55Chillies (28)41 Green chillies 8.0 6 12 55

(27)42 Green chillies 2 34 10 49(Bajji Variety) (31)43 Pepper - 8 34 55

(27)FOREST PRODUCE I44 Karaya Gum 2.0 19 35 55

(30)45 Karakkaya 2.0 44 52 55(Myrobalam) (28)46 Sugandhapala(B 3.0 26 26 55udipalagadda) (27)(Sarasaparilla)47 Aloevera 2.0 9 3 50(Green) (30)48 Aloevera - 9 1 52(White) (34)49 AmlaPowder 5.0 6.5 32 50(Hybrid) (28)50 Amla Slices 5.0 10 30 49Forest Produce (27)


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51 Honey 2.0 5.5 91 55 -(28)

52 AmlaSupari 4.0 12 35 50 4.0(28)

MEDICINAL&HERBAL PRO D VCTS53 Rosemary 4.0 15 30 55 -

(27)54 Spirulina 4.0 6 18 60 4.0Powder (28)55 Tender Bamboo 2.0 8 10 57 4.0shoots (29)56 Tulasi 2.0 6 12 50 4.0(Oscimum) (30)leaves57 Turmeric - 8 14 62 4.0

(31)58 Rose Petals 50 4.0

(30)FOODITEMS

59 Maida 4.0 4 96 56 4(27)

60 Vermicelli 6.0 4 35 55 4(28)

61 Noodles 8.0 4 77 55 5(29)

62 Fish 7 8 40 55 11(27)

CHEMICAL POWDERS63 Silicon 2.0 3 80 60 4Carbide (29)64 Cellulose 3.5 7 50 60(28) 4


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Variou s u ses of solar dried foodsSolar dried vegetables are used much the same way as fresh

vegetables. They can be fried without re hydration and these makevery good snack items. Some can be cooked in the form ofcurries/gravies after rehydration. The vegetables can readily beused in the preparation ofPulao / Biriyani. Vegetable powders canbe incorporated in the preparation of ready to make soup mixes /delicious soups. They can also be made into pickles, chutneypowders / chutneys, etc. Green leafy vegetable powders can bemade from curry-leaf, mint, coriander etc. They are reported tohave many nutritional values besides their desirable flavourproperties. Dried onion rings can be used after shallow frying togarnish dishes to give attractive look to these. Dried tomatoes arehandy to make a variety of items when fresh ones are scarce.Similarly ginger, green chillies are handy when fresh ones are notreadily available. Almost all spices can be processed to derivemaximum flavour properties. In general, retention of nutrients ishigh in solar dried items. Carrots processed in the dryer retainmaximum amount of beta carotene which is a potent antioxidantapart from its nutritional properties.

Dry fruits and fruit -based items are very much used inconfectionary and bakery industries in cakes, cookies, breads,tarts, puddings, toffees, preserves, jelly preparations etc. Fruitpowders are used in the development of ready to drink beverages.In modem times there are multifarious uses for these in foodpreparation. Apart from the above, fruit based powders have beenshown to provide a number of cosmetic applications these days.

In addition, there are several therapeutic / medicinal uses forsome of the vegetable and fruit- based items processed in the solardryer.

Sensory qualities of foods dried in solar dryer are alsoexcellent. Shelf1ife of solar dried foods is much longer comparedto open sun drying.


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CHAPTER-VISOLAR DRIED FRUIT &VEGETABLE

PRODUCTSThe "SEED" has developed healthy fruit bars in Solar cabinet

dryers, designed, formulated for the first time in the country. Sincethey are processed entirely with solar energy in highly efficientsolar dryers, they are called 'Green Energy Fruit Bars'. The rangeof natural fruit bars is very wide with 'SEED' specialtyformulations. The 'SEED' laboratory is the only R&D laboratorybased on green energy which has processed and is continuing toprocess new solar dried fruit bars and started commercializingthem in the markets in many States. To name a few, they are:mango, guava, chikku, fig, mixed fruits bars and Khatta-Meethafruit bars. They are all natural 100% healthy fruit bars withoriginal flavor and taste. In addition to these, nutritional (fortified)fruit bars, blended bars are also in the manufacturing line of avariety of fruit bars and are in the market under the 'SEED' brand.They are also marketed as slabs, rolls, bars,toffees.

Brief description of process for dehydration of some productswith necessary pretreatments is given below as examples:Fruit products:1.Mango fruit Bar

Mango fruit bars are the old traditional and popular fruit barsin the country. They are also known as 'Ampapad' in the market.No basic hygienic principles are observed since the bar isprocessed for more than 20 days in the unprotected open


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environment. Naturally this attracts dust, dirt, insects, flies,mosquitoes and other insects which find entry into the endproducts. Science and Technology was not taught to the traditionalmanufactures to improve their product in quality, processingmethodology and value addition.

The ingredients are Mango pulp, Sugar, Glucose, Pectin,Citric acid, and S02. This formulation is thoroughly mixed andspread in stainless steel trays. The yield is 40% by weight.Health benefits: King of all fruit bars, unmatched in taste &flavor, healthy bar, clean &hygienic bar & scientifically processedbars.2. Fortified fruit barsThe fruit bars are enriched with additional nutrients, like protein,calcium, vitamin-C and Beta-carotene to make the bars healthyand more nutritious. The addition of the above nutrients in rightproportion not only fortified the bars in nutritive value but alsoscored high in overall acceptance from the customers in themarket. The yield of the product is 55%. In the final productpermissible limits of retention percentage of moisture on wetweight basis is 12%. The recorded temperatures are 50-60C inthe drying cabinet and 25-35C of ambient. Theloading/spreading density of the mixture is llkg/sq.m. Dryingtime for the 2 layers is 2 days. The [mal product is cut into slabs,rolls, toffees and bars. The primary packaging of product is inpolyethylene pouches or in plastic boxes as rolls.3. No sugar Added Mango BarNo sugar Added Mango bar makes a delicious snack for mangolovers. The ripe mango fruit pulp is used for preparing the bar. Thisbar is prepared from 100% mango pulp and only Maltitol andMaltodextrin are added. In this blended pulp moisture content is


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reduced from 84 to 12% by use of solar dryer. Time of moistureremoval from blended pulp is three sunny days. The solar dried nosugar added mango bar yield is 35% by volume. The final productis checked for quality and physico-chemical properties, nutritionalparameters and microbiological attributes regularly at SEED'slaboratory. The taste is absolutely natural with no added color andflavor. The low sugar content makes it suitable for diabetics. Thenatural and hygienic method employed in making the bars makes ittotally healthy. The shelf1ife is maximum ten months.Health benefits: Low calories bar, 100% fruit bar, natural &healthy bar &nutritional bar'4. Guava Bar

Ripe Guavas are suitable for making a fruit bar. The fruits arepretreated with hot water blanching and the pulp is prepared in apulper. The guava & mango blended pulp is used for making thefruit bar. The ingredients for the bar are guava pulp, mango pulp,sugar syrup, invert sugars and Class-II preservatives. The preparedblended pulp is spread in stainless steel trays. After drying the firstlayer a second layer is applied on the dried first layer. And the sameprocess is repeated for the third layer. After drying, the bar is cutinto slabs and is packaged in polyethylene pouches. The initialmoisture content of the guava pulp is 81.7% and, it is reduced to12% in the end product. The spreading density of the pulp in thedryer is 9.0 kg/sq .m. The yield of the bar is 55%by volume. Dryingtime of the layers is 3 days. Recorded temperatures are 60C in thecabinet solar dryer and 25C ambient temperature.Health benefits:Rich in Vit - C&antioxidant, delicious taste, andhigh medicinal ueses.5. Sapota (Chikku)-Mango BarThe Kalipatti variety of sapotas are suitable for making a fruit bar.The sapotas are steam blanched and the pulp obtained using a


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pulper. The blended pulp of sapota and mango is used for makingfruit bar. The ingredients for the bar are sapota pulp, mango pulp,sugar syrup, inverted sugars and Class-II preservatives. Theprepared blended pulp is spread in stainless steel trays. Afterdrying the first layer a second layer is applied on the dried firstlayer and the same process repeated for a third layer. After dryingthe bar is cut into slabs and is packaged in polyethylene pouches.The spreading density of the pulp in the dryer is 9.0 kglsq.m. Theyield of the bar is 55 % by volume. Drying time of the layer is 3days. Recorded temperatures are 40C in a cabinet solar dryer and30Cambient temperature.Health benefits : A delicious fruit bar, gritty textured &characteristics favour and anti -diabetics and anti arthritic.6. Mixed Fruit Bar

Making of mixed fruit bar involves Mango, Sapota, Guavapulps, Pineapple and Orange juices. The fruits are subjected tosteam blanching and made into pulp using a pulper. Theingredients are five fruit pulps, i.e., Mango, Sapota, Guava,Pineapple and Orange, along with sugar syrup, inverted sugar and,Class-II preservatives. The prepared blended pulp is spread instainless steel trays. After drying of first layer, a second layer isspread on dried first layer and the same process repeated for thethird layer. After drying, the bar is cut into slabs and package inpolyethylene pouches. The spreading density of the pulp in thedryer is 9.0kg/sq.m. The yield ofthe bar is 55 %byvolume. Dryingtime of the layers is 3 days. Recorded temperatures are 40C in acabinet solar dryer and 30C ambient temperature.Health benefits :All in one, Exotic taste as in Mango, Guava,Pineapple, Sapota& Orange, Rich in nutrition - Vit - C & Betacarotene.


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7. Khatta-Meetha Mango BarThe Khatta -Meetha bars are prepared using ripe mango pulp

and raw mango juice. The readily prepared mango pulp and rawmango juice, sugar syrup, inverted sugar, class II preservatives andpermitted colors are used for the making of fruit bar. The ripemango pulp is used for sweet taste and raw mango juice for sourtaste.Health benefits : Two in one, tastes as sour as raw mango and assweet as ripe mango fruit.The prepared blended pulp is spread on stainless steeltrays.After drying of first layer applythe second layer on dried firstlayer. After drying, the bar is cut into slabs and packaged inpolyethylene pouches. The spreading density of the dryer is 7.0kg/sq.m. The yield of the bar is 55%. Drying time of the layer is 2days. Recorded temperatures are 40C in the cabinetsolar dryerand 30C ambient temperature.8.FigRoll:

Fig rolls is highly healthy 100% fruit snack fruit bar. The bar isrich sources of calcium, iron, phosphorus, Sodium, Potassium andVitamins like Vit-A, Vit-Bl, Vit-B2. Itis hygienically processedin solar cabinet dryer with economically solar energy. The fig rollsgive a delicious taste and natural flavor.Health benefits: Nature's perfect fruit, highly rich in potassium,Ca& Iron, helps weight loss and controls BP and prevention of coldand cough and constipation.9. RaisinsGrapes are dehydrated in a Solar dryer to produce raisins. Theraisins produced in this way are used in breakfast cereals, cakesand desserts. The initial moisture content of grapes is 79.2 percent.The time taken to reach 4% moisture content is 20-24 hrs (3 days).


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Grapes can be dried down to 10-15% moisture. Seedless grapes aresuitable for raisins. The process of raisins involves washing,sorting, blanching, drying and finally conditioning for one week.Before drying, the several methods of pre-treatment are applied tothe grapes.(I) Alkali treatment with 0.2% NaOH at 93C for 2 sec.(II) Dipping fresh grapes in milk,(III) Grapes exposed to sulphur fumes in air tight and specially

designed cupboards to get golden color raisins.Grapes can be loaded at 14kg per l sq. m. The dried raisins

packaged and sealed in polyethylene pouches of suitable thicknessto avoid penetration of moisture.10. Desiccated Coconut

The desiccating process of green coconut involves dehusking,splitting, grating, steam blanching, and drying in solar dryer. Thespreading density in the dryer is 3kg Isq.m. The initial moisturecontent of the product is 36.3%. Drying time for the product is 5 hrsto reach 4% moisture content. The recorded temperature of thedryer is 50C cabinet and 29C ambient. The yield of thedesiccated coconut is 50%. The dried desiccated coconut ispackaged in suitable polyethylene pouches.


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SOLAR DRIED FRUIT ROLLS / BARS

Figure 6.3: No Sugar AddedMango bar

Figure 6.8: Khatta MeetaFruit Rolls


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Vegetable Products:.1.Tomato Powder

Vegetable products dried in solar dryer are tomato, preservedtomatoes in the form of slices and powder. Hybrid Bangalorevariety and fully ripened tomatoes are suitable for processing anddrying. The initial moisture content of tomato is 94% and finalmoisture in end product is 4% for preservation for long shelf- life.The process involves washing, hot water blanching, and slicinginto 5mm thickness. The slices can load 5kg Isq.m. The drying timeof the product is 10 hrs in good sunny days. The driedslices/powderpackaged into the polyethylene pouches.2. Carrot cubesOne of the vegetable products dried in solar dryers is carrot in theform of cubes and shreds. The initial moisture content of carrotwas 86.0% and the final moisture content should be less than 4%for preservation and long shelf-life. (Total yield is 15-18 percent oforiginal weight).Process: Generally large carrots, high in solids but free fromwoody fiber, should be selected for dehydration. Clean and washthem, peel and slice into pieces or shreds. The pieces are thenblanched in a 2% common salt solution for 3-4 minutes at 93C.Soaked in 2% starch solution for 15 minutes and dried in traysinside the solar dryers. The time taken to reach 4 percent moisturecontent is 10-12 hrs on good sunny days (1 day and half), Afterremoving from the dryer, the dehydrated carrots are packaged andsealed in high density polyethylene pouches.Health benefits: Rich in Vit - A, delicious ingredient in culinary,healthy vegetable drink and dry cubes in fried rice.3. Ginger PowderDehydrated and ground ginger is becoming more popular thanfresh and whole ginger. Dehydrated ginger powder can be stored


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for long periods without deterioration. It is a constituent of manyspice mixtures and is used in ayurvedic medicines also. Itis usedextensively to flavor various kinds of food preparations like bread,cakes, cookies, pies, puddings and beverages. The initial moisturecontent of ginger is about 81%. To produce dehydrated ginger andto improve thestorage conditions, the fmal moisture should be 4%orless.Process - For preparing dry ginger, the raw ginger rhizomes aresoaked overnight. They are thoroughly washed in water to removethe soil and dirt. The outer skin is removed carefully with a bambooknife/wooden scrapers to preserve the pleasing aroma in driedginger.

The scraped ginger roots are sliced, ground and spread in atray at the rate of 5 kglsq.m. Drying process is continued on 2sunny days (16 hrs) in solar dryer. The dried ginger is ground intopowder and is well packed in suitable HDPE pouches.Health benefits : Lemony flavor, excellent spice in culinary,healthy mixed drink and high medicinal value.4. Amchur powder

Raw mangoes have aninitial moisture content of 87.5%. Theprocess involves washing, peeling, slicing and salt pre-treatmentof raw mangoes. The mango slices can be spread in the dryer at therate of9.0 kglsq.m. The temperature ofthe dryer cabinet is 50C &ambient temperature is 28C. The product can dry within 16hrs ongood sunny days. The yield of the product is 22 percent. The finalmoisture content ofthe product is 4.0 percent.5.RagiMalt

Ragi malt is a bequest from the ancestors, refined by SEED.Malted Ragi or Wood Ragi is made using a safe and fuel savingtechnique. It is an ideal cereal food for the babies, the young andthe elderly. Ragi malt is different from Ragi flour.


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It is made from powdered, slightly roasted, germinated,dehydrated Ragi seeds in a controlled environment. The Ragiseeds are dried in a hygienic environment in a solar dryer. Thisscientific method employed for the making of Ragi Malt helps inoptimum retention of nutrition, like proteins, fats and minerals.Ragi is also blended with cereals like green gram and nuts makemore healthy drink.

Ragi malt and Blended malts are easily digestible. Itis rich inhigh levels of Calcium and its protein content is rich in methionine,which is a sulphur containing amino acids. It also has a highvitamin and minerals content and low fiber content. The low fibercontent is achieved by sieving the meal through a fine mesh orcloth.

Malting ofRagi does not pose problems like mold growth oran off odor development during germination. All the abovementioned qualities makes Ragi malt a better cereal than tropicalcereals such as rice, maize, j owar and bajra.

It tastes good, gives a desirable aroma, keeps well for quitesome time and becomes slurry with water without lumps.Therefore, it is an ideal nutritional drink produced in the SEEDlaboratories with scientific methods.Health benefits: Ideal cereal sprouted ragi malt, easily digestible,tastes good &desirable aroma, high levels of Ca, and rich proteinand other minerals.Green leafy products:1.Curry leaves

The matured curry leaves are removed from the stem andwashed. The washed leaves are blanched in a solution containingmagnesium oxide 0.1% for 1minute at 90C and spread in a tray ata rate of 6 kg/sq.m. Yield of the product is 35%. The cabinettemperature is 55C and 30C ambient. Final moisture is 4 percent


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in the dried leaves. After drying for 8 hrs, the leaves are ground intopowder and packed in polyethylene pouches.Health benefits :Important ingredient in culinary, healthy, highlyrich in protein, crude fiber, Ca, Fe, P,Vit - C, Authentic flavor andtaste, weight loss, antiages, prevents weakness, cures diabetics andhair growth 2 times faster.2. Gogu leaves

The matured Gogu leaves are taken off from the stem andwashed. The washed leaves are blanched in a 0.1% solution ofmagnesium oxide for 1minute at 90C and spread in a tray at a rateof5 kg/sq.m. Yield of the product is 16%. The temperature insidecabinet dryer is 55C & 30C ambient. Final moisture content of 4percent is noted in the dried leaves. After drying for 15 hrs, theleaves are ground into powder and packaged in polyethylenepouches.3. Mint leaves

The mint leaf powder is used extensively to flavor foods.Matured mint leaves are washed and blanched at 90C for 1minutewith addition of 0.2% magnesium oxideto retain color andnutritional value. The initial moisture content of mint leaves is85%. For preservation and to improve the storage conditions, thefinal moisture content should be 4% or less and the yield 17% byweight. It is spread in a tray at a rate of 5 kg! sq. m and dried in solardryer for 5 hrs at 55C in the cabinet when ambient temperature is28C. The dried leaves are then ground to powder and packed inpolyethylene pouches of suitable thickness.4. Solar dried Amla Powder

Amla powder always has many medicinal values. Itsproduction in hygienic environment protects its nutritional valuesand renders the powder free from insects and dust. This isspecially processed in solar dryer with blue filter.


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The Amla fruit is enriched with Vitamin-C by a specialprocess developed in "SEED" laboratory with 20% more retentionof Vitamin-C. The powder also has a high Ascorbic Acid content.

Amla powder has a wide range of applications and isconsidered as an AyurvedicMedicine.It has a lot of medicinalapplications and other uses too. It shows a lot of improvement inthe following areas:-

Itacts as an effective natural cure for indigestion, acidity,constipation, gastric troubles, and flatulence.Itis helpful in improving liver function.Ithelps inlowering cholesterol and blood sugar levels.

Amla powder produced by 'SEED' enhances the naturalproperties of Amla while eliminating almost all chances ofcontamination. Ithas great potential in the domestic and exportmarkets.5.AmlaSupari

This is a special product which leaves a refreshing anddelicious taste in the mouth. It can be used as a healthy mouthfreshener in place of betel nut Supari. The fruit is speciallyprocessed to produce Supari by blending with spices and menthol.Health benefits : Highly rich in Vit - C, mouth freshner withspices and menthol, refresh and tasty and excellent medicinalvalues.


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SOLAR DRIED FRUITS / VEGETABLES


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Figure 6.18:Mint Leaves and Powder


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Analytical Tests to be conducted on Solar DriedFruits, Vegetables and their products.

Drying is the most appropriate way used in preserving manyfoods in rural areas. Ithas the advantage of being a traditionalpractice, well understood technology, and low cost of equipment.Drying is done by simple drying in the open sun or using a solardryer, or a mechanical dryer. During drying, water is removedfrom the product by the combined effects of three basic elements -Temperature, Humidity and Airflow. Drying is successful only ifthe relationship between these elements is correct. The spoilage offresh products is mainly caused by the growth of microorganismspresent in the product having high water content. When themoisture content is lowered below a certain level, their growth isarrested. Drying stops only the growth of microorganism. Decaystarts immediately when the water is in contact with the produce orproduct orhumidity is reestablished. A correct drying methodmust be adopted followed by correct storage. When looking intochoice of a drying method, it is very important to defme thepurpose of drying the raw material; whether it is meant for productpreservation, i.e., to prevent deterioration and therefore loss ofvalue, or for product refinement i.e., as a stage in processing a rawproduct into another form for final consumption. In processing thefruits and vegetables, the value addition of the product, latter is theusual aim and the motivation for an investment in time, labour andmoney by the producer in the introduction or improvement of adrying device benefits he expects to derive from the productrefinement.

Solar dryers have been developed to overcome some of theshortcomings met with in sun drying. Often very simpleinnovative devices are developed and used to enhance the effect ofthe sun's heat and to protect the product from loss of color andvitamin content (raisins & dates). Fruits like mango, papaya,


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guava, grapes, figs, apricots and pineapple are generallydehydrated in order to be preserved for longer periods. A puree' ofthe fruit is dried into a thin layer resulting in a product known asfruit leather or fruit bar. This is generally eaten as a snack food.Bethe product may be sweetened by the addition of sugar or itsformulation may be modified by the incorporation of ingredientssuch as chopped nuts, grated coconut or ground spices.

The process of drying of fruits involve in some cases certainpre-treatments aimed at preserving the color and preventingmicrobial spoilage. Fruits are dipped in sodium metabisulphitesolution for a particular period or exposed to sulphur dioxidefumes by burning sulphur in order to retain the colour and to slowdown browning discoloration in the drying process. Further, thistreatment also retards the growth of mold and yeasts. The productis then dried to reduce moisture content to 15-25%.General methods of Food analysis

Food products, fresh, raw, and processed ones, can beanalyzed for physical, physic-chemical, microbiological andnutrient composition. In addition, sensory / organoleptic qualitiescan also be determined.a) Analysis of pulp prior to dryingThe fruit, fruit pulp/puree or vegetable puree or fruit pieces are tobe analyzed for moisture, protein, lipid, fiber, organic acids,pigments, enzymes, vitamin-C, carotenoids etc. The details of themethods are covered under the analysis of dried products in manystandard text books.b) Acidity of fruit pulp.For quick determination of the acidic or alkaline nature ofpulps/purees, litmus papers are used. A commercially available pHmeter is used for determining the degree of sharpness or intensityofthe acidity ofthese.


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c) Physico-chemical nature of dried fruits and vegetablesVegetables and fruits can be analyzed for moisture, dryness,

rigidity, weight, volume, gelatinization of starches, denaturation ofprotein, volatile flavor, deterioration during shelf life etc. by wellestablished standard procedures.d)Analysis of chemical constituents and nutrient composition

Fruits and vegetables can be assessed for variants likemoisture, color pigments, enzymes, flavours, componentsresponsible for flavor, deterioration of shelf life, etc., by standardtechniques.e)Nutrients composition

Almost all the nutrients in fruits and vegetables, namely,different classes of carbohydrates, lipids, proteins, individualvitamins, and individual minerals can be determined.f)Microbiological quality

Vegetables and fruits have high water content and are easilyspoiled due to rotting. A number of microorganisms areresponsible for the spoilage. They are usually present on thesurface of the materials, grow and multiply over a period of timeand eventually cause decay or spoilage. Extensive information isavailable on microbiological testing procedures to determine theconcentration of various organisms, to detect the presence ofpathogens and to assay microbiological toxins. In a well equippedlaboratory, both instrumental and non-instrumental methods areemployed. For testing on site and for obtaining results rapidlyduring a manufacturing shift, there are a few standard test systemswhich are beyond the reach of many micro entrepreneurs. Rawmaterials of all categories and finished goods need to be screenedthoroughly in the quality assurance / quality control laboratory.Methods of assay use solid and liquid microbiological media, pure


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test cultures, incubators, incubation atdifferent temperatures forvarying periods, microscopic examination, etc. However, thesemethods are highly reliable and yield very useful data.


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DIFFERENT FOOD QUALITY PARAMETERSA brief indication of important quality parameters is given in tabular

form providing awareness of the properties of food productsPhysic Physico - Chemical Microbiol Nutrie Sensoral Chemica Constituents ogical nt yQualiti I Qualit Comp Attribes Characte y onents utesristicsAppearanc Starches Moisture Yeasts Starches Coloure &gumsbe LipidsProteins Sugars AppearanSize, shape come less Carbohydrates Molds Glucose ce& Fiber soluble Fructose Solid/semishrinkage. Hydrophi and insoluble Bacteria Dietary solid

Distortion lie Cellulose, fibre Hardnessof Altered Lignin Enterobact Crude GlossinessCells & colloidal Chlorophyll or fibre ShininessCharacter Carotene Texture-Capillaries istics Anthocyanins, Micro Ascorbic Rough/coSugars & Lycopenes, Coccus acid arse/Altered

salts Tannins Beta Fibrous/sEscape Acidity/pH Pseudomo carotene mooth/fmtexture. from value nas e

Viscosity damage Enzyme activity Taste-Liquidity / cells into Organic acids, Streptococ Sweet,water Other organic cus SourlBitteflowy Denaturat compounds, rPorous &light. ion of Storage Stability Leuconost Astringentprotein promoting oc InsipidHard & Loss of Antioxidants, MouthHeavy turgor Emulsifiers Escheria feelReconstitu Loss of ExtractslFlavour coli &Flavourtion voltatile sRate. Flavours LactobacilQuick Brownin Ius, etc.Solubility g reactionCasehardeningSurfacearea


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Figure 6.22: Research Scientists performingAnalytical tests in the Laboratory


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Figure 6. : Automatic Packing Machine in Processing section

Figure 7 . : Automatic Packing Machine in Processing section


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FURTHER REFERENCES1. Palaniappan.C (2008) "Perspectives of Solar FoodProcessing in India." Planters Energy Network.2. Rathore N.S (2011) "Anew approach for drying of animalFeed through roof integrated forced. Convection typeSolar Dryer on Industrial Scale" Paper presented at"National workshop on Solar Food Processing Technologiesto Rural women and youth for High Income generation & JobOppurtunities on 11-12 February 20 11at JNTU, Hyderabad.3. Ajay Chandak, Suni1.K.S, Shivanand.S (2011) "Solar Ovensand Dryers for Food Processing Applications"Paperpresented at "National workshop on Solar Food ProcessingTechnologies to Rural women and youth for High Incomegeneration & Job Oppurtunities on 11-12 February 2011 atJNTU, Hyderabad.4. Ramakrishna Rao M, Veena V, "High nutritive values of

dehydrated leafy vegetables in solar dyer" ,Presented atNational Seminar in Commemoration of the bicentenary ofNicholas appeart's innovation of thermal processing of foodson 18-19 September 2010 at nCT, Hyderabad. (Awardedsecond Prize)5. M. Ramakrishna Rao,RadhaMadhaviBandBasamma B.C"Development of new process of Fig fruit bar in

Innovative Solar Dryer"Presented at National Seminar inCommemoration of the bicentenary of Nicholas appeart'sinnovation of thermal processing of foods on 18-19September 20 10 at nCT, Hyderabad.6. RamaKrishnaRao. M (1998) "Solar Powered air dryer todry Forest produce" article inIREDANews (July-Sep).7. RamaKrishnaRao. M (2001) "Dry Food products to

flourish in Andhra with solar PV" article in IREDA News(September).8. RamaKrishnaRao. M (1999) "Solar Dryer for chemical &pharmaceutical Industry" invited talk at "Business meet onSolar Energy for pharmaceutical Industries".


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9. RamaKrishnaRao. M (2004) "New Solar Powered Solar airDryer for Food Processing Industry" Proceedings of theNational workshop on "Solar drying Technologies & theirapplications in India" atHyderabad.

10. JagadeeswaraRao.R (1997) "A delicacy from Mango pulp"article in "THEHINDU" (July9th)11. RamaKrishnaRao.M, Sarojini.GandVeena.V(2005) "SolarDrying for safe and quality Mango bar" National SeminaronFoodSafetyandQuality control in India (ANGRAU).12. Dr. Sarojini.G (2004) "Solar Drying of Sapota" Paperpresented at workshop on "Cashew and Sapota Valueaddition" held atHyderabad onMay 8th13. Veena.V, Arani.N, Sarojini.G and RamaKrishnaRao. M(2006) "Studies on Solar dehydration of Sapota Fruits"November 2006.14. Veena.V, Sarojini.G and RamaKrishnaRao. M (2006)"Studies on Solar dried Blended Fruit Bars" Proceeding ofICORE2006Feb 8-11,Hyderabad.15. RamaKrishnaRao. M (2005) "High Quality Raisinsprocessed in Solar Powered solar air dryer".16. Sarojini.G ,RamaKrishnaRao. M and Veena.V(2005)"Raisins Processing using Solar Dryer" Abstracts of Poster

Session- NCICFT (OUUniversity)17. RamaKrishnaRao. M (2001) "Solar Food ProcessingTechnology" article in IREDANews (July-Sep).18. Sarojini.G ( ) "Horticultural products processed in Solarpowered dryer".19. RamaKrishnaRao. M (2002) "Solar Food ProcessingTechnology" article in Business meey on "Solar FoodProcessingTechnology"held atHyderabadon7thSeptember.


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VIP'SCOMMENTS ONSOLAR DRYER TECHNOLOGY

It is apleasure to note thepioneering work that is being done to usesolar energy for drying. This has immense potential in a countrylike ours. It can go to help a large number of small land holdersand income households. - Dr. C. Rangarajan, Governor, AndhraPradeshI am sure this will be a wonderful equipment, especially at ruralareas, provided there is a little bit of skilled labour to handle thesame. - Dr. V.Prakash, Director, Central Food TechnologicalResearch Institute, MysoreLearning movements with Dr. M Ramakrishna Rao and thus onsolar powered drying systems to be used in spices industry. BestWishes. - SriKoshy John, Director (Dev.), Spices Board, Koshi.Impressed with the innovative technology. Wishing you all the bestin your endeavors. - Sri Prem Chand, Managing Director,NEDCAp, HyderabadHighly impressed by the work carried out by the dedicatedworkers. - Dr. Ramesb Bhat, Dy. Director, National Institute ofNutrition, Hyderabad.Prof Rao, known for his innovations, has created anotherimpressive unit/society which is helping the organised sector - Dr.R.S.Sirohi, Director, 1.1 . T.DelhiHappy to discover this way of drying vegetables so important forlocal economy. Hope you will export to France- Duchesne AnneLa Hurellerie 72500JupileesIt is wonderful work. Solar Energy is put to most effective use.Industry on a Mega scale may be planned after thorough marketsurvey - Dr. V. Malakonda Reddy Chairman (Rtd.) CBIT.,Hyderabad.After a long long time, it was a great pleasure to reestablishcontact with Prof M Ramakrishna Rao. I was greatly fascinatedand inspired by the work and innovative products developed by


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SEED. Clearly there is immense potential for scaling up thisactivity. The model and the outputs deserve to be replicatedseveral fold. I convey my sincere good wishes for every success ofProf Rao's venture- Prof. P . Rama Rao, Former DST Secretary,New Delhi.SEED has done excellent work in the development of Solar dryers.Its efforts for provision of technology in rural areas for incomegeneration are well appreciated. I wish best of luck to them -Dr.T.C Tripathi, Advisor, Ministry of New &Renewable Energy,Govt. of India, New Delhi.Innovative approach to a topical need of the country, especially forgainful utilization of natural resources in the rural areas. Take itto greater heights - my best wishes- Dr. V.C Goyal, Director,Science & Society Division. Dept. of Science & Technology, NewDelhi.Solar thermal displayed and shown to us was really appreciatedand its aroused me to wanting to have same in Nigeria - Engr.Nura Abba Alkali, Rural Electrification Agency, Abya, Nigeria.fery interesting and profitable venture- Engr. Godwin O. Ekpe,RuralElectrificationAgency, ABUJA.An inspiring effort which needs marketing- Dr. ArcotRamachandra, Bangalore.fery good initiative of combining both renewable energy and foodtechnology. Definitely it will be helpful the farmer and smallentrepreneurs. The efficiency of solar dryer may be im

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