Aloe vera L. processing and products: A review

Int. J. Med. Arom. Plants, ISSN 2249 – 4340REVIEW ARTICLE

Vol. 3, No. 4, pp. 492-506, December 2013

*Corresponding author: (E-mail) vkchandegara <@> jau.in http://www.openaccessscience.com

© 2013 Copyright by the Authors, licensee Open Access Science Research Publisher. [email protected]

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported (CC BY-NC-ND 3.0) License (http://creativecommons.org/licenses/by-nc-nd/3.0)

Aloe vera L. processing and products: A reviewV. K. CHANDEGARA1*, A. K. VARSHNEY2

1Department of Processing and Food Engineering, College of Agricultural Engineering and Technology,Junagadh Agricultural University, Junagadh – 362 001 (Gujarat), India2Polytechnic in Agro-Processing, College of Agricultural Engineering and Technology, Junagadh Agricultur-al University, Junagadh – 362 001 (Gujarat), India

*Corresponding author: Tel: +91-0285-2671018

Article History: Received 7th November 2013, Revised 27th December 2013, Accepted 28th December 2013.

Abstract: Use of Aloe vera in nutritional, pharmaceutical and cosmetic preparations draw attention for generation ofscientific information. Looking to the importance of biologically active components possessed by the leaves of the Aloevera plant and its wide spread use, it has become imperative that, the leaf should be processed with the aim of retainingessential bioactive components. In this review paper, different processing aspects like harvesting, handling, transporta-tion, Aloe vera gel expulsion, gel extraction and storage of gel were critically described from different references. Differ-ent product prepared from Aloe vera whole leaf and gel like food products Aloe juice, Aloe health drink, Aloe desert, etcwere reviewed. Aloe vera processing methods for gel expulsion by splitting of leaf, roller method, crushing of whole leaf,hand filleting methods and stabilization are described with various references. Present processing techniques aims at pro-ducing best quality aloe products but end aloe products contain very little or virtually no active ingredients. Hence, ap-propriate processing techniques should be employed during processing in order to extend the use of Aloe vera gel.

Keywords: Aloe vera gel expulsion; Aloe vera gel expulsion extraction; filleting; leaf splitter method purification; stabi-lization.

Introduction

Medicinal plant has specific property andspecific use owing to their biological group ofcompounds. Several species of the genus aloehas been in use under the common name of aloeviz. Aloe vera, Aloe barbadensis, Aloe ferox,Aloe chinensis, Aloe indica, Aloe peyrii, etc.Amongst these Aloe vera Linn syn. Aloebarbadensis Miller is accepted unanimously asthe correct botanical source of aloe. Aloe vera amember of the lily (Liliaceae) family is a spiky,succulent, perennial plant and a native to warmdry regions. It is popularly grown as indoorsplant and cultivated almost everywhere in theworld, both as a houseplant and for its medicinalqualities. There are about 300 identified species.Aloe vera Gel is the colorless mucilaginous gelobtained from the parenchymatous cells in thefresh leaves of Aloe vera (L) Burm. f.(Liliaceae) (Gilman, 1999; Moore, 2001).

Aloe vera Latex (Aloin, a bitter tasting pur-gative, is destructive to healthy tissue and cells)is obtained from specialized cells known aspericyclictubules that occur just beneath the ep-idermis or rind of the leaves.

Aloe vera plants products are biologicallyactive and hence their post harvest handling andprocessing needs great care. The time, tempera-ture and sanitation are the prime requirement forprocessing to put the Aloe vera plant products inactive form. The most important factor is thehow to extract the gel from Aloe vera leaf and topreserve it for long duration for its utilization incosmetic and pharmaceutical products.

Handling of Aloe vera leaves

Aloe vera barbadensis can grow up to 100cm height, although most specimens are 30 to60 cm in height. It has thick leaves that grow ina rosette shape. The parenchyma cells of the

http://www.openaccessscience.com

mailto:[email protected]

http://creativecommons.org/licenses/by-nc-nd/3.0

493Int. J. Med. Arom. Plants Aloe vera: a review

Chandegara and Varshney http://[email protected]

leaves contain large quantities of pulp. Thefleshy leaves with serrated edges that arise froma central base and grow to nearly 30 – 50 cmlong have 10 cm width at the base.

The plants can be harvested every 6 to 8weeks by removing 3 to 4 leaves per plant. Aloevera leaves are normally sensitive to subfreez-ing temperatures The weather conditions arehighly affect the Aloe vera processing schedule.Pulling back on the green leaf and cutting at thewhite base carry out the harvesting of the Aloevera plant. To avoid bio-degradation the Aloevera leaf is harvested and pulled carefully fromthe mother plant so as not to break the rind.

Biological activity loss is due to the micro-bial decay of the gel. The first exposure of theinner gel to microbes is when the leaves areharvested from the plant. Leaves in which thebase is not intact and sealed will greatly increasethe microbial counts in the finished product.Higher level of microbial counts significantlyreduces the biological activity in the product.The other major source of microbial contamina-tion comes from the rind of the leaf. The har-vested leaves were kept in the icebox at 4 -5 0Cand transported to the processing unit.

Aloe Vera leaf characteristics and composi-tion

Physical structure of Aloe vera leaf

The Aloe Leaf consists of three layers:

A. The outer thick rind

B. A viscous, jelly like mucilage layer intowhich the vascular bundles, attached to the innersurface of the rind, protrude.

C. The fillet proper, which has structural integri-ty consisting of hexagonal structures containingthe fillet fluid. This is the water storage area forthe plant.

Chemical composition of Aloe vera leaf

The main constituents of the Aloe vera leafare: (i) Aloin: It is an irritant laxative containedin the yellow sap of Aloe, which is a constituentof the Anthraquinone complex, (ii) Methanol-Precipitable Solids (MPS): When alcohols are

added to Aloe solutions about 20-25 % of thetotal solids come out of solution or'precipitate'. The chemical constituents of Aloevera barbadensis (Joshi, 1998) consists of main-ly polysaccharides, glycoprotein and salts oforganic Acids. The polysaccharides representabout one-half to two-thirds of the MPS orabout 10-15% of the total solids. (iii) Polysac-charides: There are over 200 constituents in Al-oe vera, the single most important constituentbeing the polysaccharides.

Biologically active chemical constituents of Al-oe vera leaves

The gel contains 98.5 % water having pH of4.5 and also contains many polysaccharidessuch as Glucomannan, Acemannan etc., in ac-tive form in the leaves of Aloe vera.Glucomannan is a good moisturizer and mainlyused in many cosmetics products (Henry, 1979)whereas Acemannan, the major carbohydratefraction in the gel, is a water-soluble long chainmannose polymer which accelerates woundhealing, modulates immune function and antivi-ral effects.

Processing parameters of Aloe vera

Time, temperature and sanitation (TTS) arenecessary to preserve these biological activities.The TTS Aloe Process not only preserves thenatural biological activities of Aloe vera but alsoenhances the physical stability of the finishedproducts.

Timing of process

Leaves show losses of biological activitybeginning at six hours following harvest whenthe leaves are stored at ambient temperature.Most biological activities are completely lostafter 24 hours at ambient temperatures. Thelosses of activity appear to be the result of en-zymatic activity after the leaf is removed fromthe plant. In fact, it has been shown that the gel,once extracted from the leaf, has greater stabil-ity than gel, which is left in the leaf. This meansthat shipping of leaves, even at refrigeratedtemperatures, will result in loss of biological





activity. The overall timing of TTS productionphases is extremely critical. The processingmust be completed within 36 hours of harvest-ing the leaves (http://www. aloecorp.com).

Process Temperature

The Aloe gel processing temperature playsvery important role for gel quality for cosmeticand medicinal use.

A. Flash Cooling

As a crucial step to preserve biological ac-tivity, the gel is cooled to below 5 0C in ten tofifteen seconds following the gel extraction.Rapid cooling not only slows enzymatic andmicrobial deterioration of the gel, but also aidsin reducing the microbial counts in the product.

B. Pasteurization

Biological activity remains essentially intactwhen the gel is heated at 65 0C for periods ofless than fifteen minutes. Extended periods orhigher temperatures will result in greatly re-duced activity levels. The best method of pas-teurization is HTST (high temperature shorttime), which exposes the gel to elevated temper-atures for periods of one to three minutes. Onceheated, the gel is flashing cooled to 5 0C or be-low.

C. Concentration

The gels obtained using the pasteurizationand flash-cooling methods can be concentratedunder vacuum without the loss of biological ac-tivity. The concentration operation must be con-ducted under 125 mm mercury vacuum at tem-peratures below 50 0C and must not exceed twominutes. Higher vacuums and temperatures willcause activity loss as will extend concentrationtimes.

D. Drying

The concentrated product can then be freezedried at temperatures between -45 0C and 30 0Cor can be spray dried with product temperaturesbelow 60 0C without losses in biological activi-ty. For export purposes (especially for cosmeticindustry), dried Aloe gel is favoured. Gel filletscan be directly dried by dehydration under a lowheat. However, gel liquid is mostly dried either

by spray drying or freeze drying (Waller et al.,2004). Freeze-drying involves placing frozengel under a high vacuum. Water sublimes fromthe frozen gel as it gradually heats. Spray dryingis a two step process. The process begins withmatrix development. The matrix is pumpedthrough a spray dryer chamber. Fluid is sprayedas a fine mist out a series of nozzles through thischamber. The chamber is heated between 50 to90 0C causing water to evaporate and the aloematrix to dry. With temperature playing a cru-cial role in maintaining natural plant products,freeze-drying is favoured. Heat is not added sothat chemical transformations are minimizedand the biological activity of the gel is not alte-red as may be the case with spray drying.

Freeze drying of the Aloe vera fillets were atlow temperature under vacuum found the max-imum value of rehydration ratio and water hold-ing capacity (Andani, 2010).

Osmotic drying of Aloe vera (Aloebarbadensis Miller) cubes were osmosed for 4h in sugar syrup of different concentration andtemperatures at constant syrup to fruit ratio of5:1. Drying of Osmosed and unosmosed Aloevera samples at different temperature with con-stant air velocity, observed water loss and solidgain during osmo-drying. (Simal et al. 2000,Chang et al. 2006, Vega et al.2007, Segovia etal. 2009 and Pisalkar et.al. 2011).

Processing of Aloe vera

The potential use of Aloe vera products of-ten involves some type of processing, like heat-ing, dehydration and grinding (Chang et al.,2006). Unfortunately, because of improper pro-cessing procedure aloe products contain verylittle or virtually no active ingredients(Ramachandra and Rao, 2010), so it has becomevery important to evolve a better method ofpreservation for increasing the shelf life andmaintaining the quality of Aloe vera gel.

Washing of Aloe vera leaf

When Aloe vera leaves are harvested, it con-tains dirt and other impurities. The yellow fluidsecretion from the harvested leaves should becompletely removed from the leaf for its pro-





cessing and purity of products. The leaves werethoroughly washed with fresh water with me-chanical washer. In the Aloe vera processingindustry, leaves are initially washed in a steriliz-ing solution, a 200 ppm solution of sodium hy-pochlorite (Waller et al., 2004). If leaves areextremely muddy when delivered to the gel fac-tory they are pre-washed in a basin of deionisedwater. In some cases, the pre-wash step involvesscouring the leaf rind with soft brushes(McAnalley, 1990).

Pre-treatment for Aloe vera processing

The Aloe vera leaves are preconditioned bysun drying, shade drying and by steaming. Thestudy revealed that, two days sun or shade dry-ing, yielded highest crude gel recovery and less-er residual time without aloin contain as com-pared to the fresh leaves el. They have also re-vealed that the matured leaves lead more crudegel recovery as compared to immature leaves.The immature leaves take more time in pro-cessing by manually as well as mechanically forgel extraction (Anonymous, 2008a).

Study on gel extraction efficiency by takingdifferent pretreatments such as brine, lye, waterand without treatment i.e., control found thatscrapper method with brine treatment is mostsuitable for extraction of gel that gives 93.42 %gel extraction efficiency (Anonymous, 2008c).

Peeling of Aloe vera leaf

The removal of outer skin and rind is themost tedious operation for mechanical machinedue the shape of Aloe vera leaf. Precautionsshould be taken to avoid contamination of innerpart with exudates secretion to maintain purityof products.

Hand filleting

In order to avoid contaminating the internalfillet with the yellow sap, the lower portion i.e.25 mm of the leaf base (the white part attachedto the large rosette stem of the plant), the taper-ing point (50 –100 mm) of the leaf top, and theshort, sharp spines located along the leaf mar-gins are removed by a sharp knife. The muci-

lage layer below the green rind avoiding thevascular bundles and the top rind is also re-moved with the help of knife. The bottom rindis similarly removed.

The hand - filleting method of processingAloe leaves was developed to avoid contaminat-ing the internal fillet with the yellow sap. In thismethod the rind is removed by using sharpknife, keeping anthraquinone level low, but inthis process the most of the mucilage is left onthe working table. During processing operation,the lower 25 mm of the leaf base (the white partattached to the large rosette stem of the plant),the tapering point (50 –100 mm) of the leaf top,and the short, sharp spines located along the leafmargins are removed with the help of sharpknife. The knife is then introduced into the mu-cilage layer below the green rind to remove toprind and similarly the bottom rind is removed(www.bonasana.com).

Mechanical filleting method

Mechanical filleting is the most commonlyused method in the industry for gel extractionfrom the Aloe vera leaves (O’brien, 2005). Thisprocess takes place on a conveyer belt, equippedwith rollers and blades. Initially, the leaf (uppersurface facing downwards) is passed over ablade mounted on a table. The upper rind is cutaway in one swift movement. The exposed gelsurface is then longitudinally sliced from theupper to lower surface but not completelythrough the lower rind surface so that the curvedlower rind becomes flat. The lower rind cannow be easily removed by passing it over theblade as before. The gel slices are then collect-ed. The next step in gel processing is the remov-al of cellular material from the gel. The gel fil-lets are chopped into small chips and de-pulpedusing sieves3. It can also be liquidized as in thefruit juice industry and filtered to remove cellu-lar material. The liquid gel is obtained, only af-ter the removal of fiber. The gel in the crudeform is sold as a commercial product. For thelong term storage the gel is mixed with activatedcharcoal for purification and then filtered. It canalso be preserved, by putting some stabilizingagent. The treatment with activated charcoalensures that any anthraquinone compounds in



www.bonasana.com



the gel are removed. In the A. vera industry,0.05 % w/v charcoal is added to 2000 L gel, ap-proximately gel takes one hour to pass throughCelite Filteraide for filteration.

Whole leaf processing

In this process, the base and tip are removedand then the leaf is cut into sections and groundinto particulate slurry. The material is thentreated with chemicals, which breaks down thehexagonal structure of the fillet releasing theconstituents. Then by expression and extraction,the undesirable elements can be selectively re-moved, while maximizing the desired constitu-ents. This process, performed properly, can pro-duce a constituent-rich juice (generally contain-ing 3 times or more constituents than hand fil-leted juice), which should be virtually free ofthe laxative anthraquinones; this process wasdeveloped in the 1980’s(http://www.wholeleaf.com). The data of handand whole leaf filleting which reveals that thequantity of desirable polysaccharides is 2.5 to 3times higher as compare to hand filleting meth-ods (Table 1).

In the method of whole leaf processing, thewhole leaf is coarsely chopped and the rind par-ticles are removed by passing through filters ofvarious porosities. The anthraquinone are re-moved by using charcoal. This method producesa product rich in carbohydrates but also muchhigher in mineral salts than the other methods(Danhof, 2000).

Table 1: Effect of leaf processing method onyields and constituents.

Process Fraction Hand Filleting(%)

Whole Leaf(%)

Total solids (Without pre-servatives or additives)

0.45 – 0.65 1.30 – 3.50

Polysaccharides 0.12 0.16Source: http://www.wholeleaf.com

Roller squeezing method

In this method of peeling the Aloe vera leafis passed between two parallel rollers rotating inopposite direction and at different speed. The

pair of rollers with variable apertures are ar-ranged to accommodate the varying width andthickness of the Aloe vera leaf. The purity is notmaintained in this method of peeling as there ismixed of outer exudates with inner pulp.

In the roller method of gel expulsion, theleaves are passed through rollers and the fillet“pops” out, same time more pressure is appliedto the pericyclic tubules for gel expulsion. Alow cost gel extractor had developed comprisingof two roller having diameter 118 mm andlength of 245 mm with one roller has continuousslope (Anonymous, 2008a). Similarly, low costAloe juice extractor has also developed (Anon-ymous, 2008b). Similar machine developed hav-ing two stainless steel roller rotated with chainand sprocket (Anonymous, 2008c).

A 60 – 80 kg leaves/h capacity, Aloe veragel (fillet) extractor was designed and developedby providing adjustable gap in between thecrushing rollers, so that only the gel is just ex-tracted and over crushing of the leaves can beavoided(Anonymous, 2008d) .

An apparatus for extraction of uncontami-nated Aloe vera gel from the leaves of Aloe veraplants had developed in which the harvestedleaves of the Aloe vera plants are placed be-tween a pair of endless moving belts. The leavesare passing through a number of crushing rollersarranged in a desired pattern. The rollers firstcrush the core of the leaf to enable the gel toflow internally while a second set of rollers ex-trudes the gel from the leaf. The crushed leafand extruded gel is then fall on a drain grate toenable gravity flow for the separation of gelfrom the crushed leaves. The proper slope isprovided to the drainage grate, so that the leaveswill slowly move across the drain grate to ena-ble separation of the gel. The leaves are re-moved from the gel collection area before itmixes with the flowing aloin to avoid contami-nation (Tumlinson, 1985).

Aloe vera leaf splitter

Aloe vera leaf splitter is very advance meth-od of peeling in which, leafs are spitted by me-chanical machines that simulates hand filletingoperation.



http://www.wholeleaf.com




A thin wire is used to split the Aloe veraleaf, which can be placed at varying distancesfrom the vascular bundles. The wire is allowedto go too close to the rind, the extracted gel willcontain more anthraquinone as well as more ofthe mucilage, if it is too close to gel fillet, andthen less anthraquinone as well as less mucilagewill be obtained.

Aloe vera plant leaf to a cutting knife of de-veloped apparatus. The apparatus is designed totransport the leaf on an endless belt conveyor onwhich the leaf is laid down flat and lengthwiseon the conveyor belt. A second endless beltconveyor travels in the same direction and at thesame speed as the first endless belt conveyor butis disposed at a right angle to the first endlessbelt conveyor at the feed end of the apparatus.The first endless belt conveyor in its travel isslowly twisted towards the second endless beltconveyor and by the time the first endless beltconveyor has reached the end of its travel, theleaf has been turned from a flat condition to avertical position and is sandwiched between thetwo sets of endless conveyor belts. The leaf nowstanding on its edge between the aforesaid setsof endless belt conveyors, the same is fed intothe apparatus where the leaf are cut into twohalf and thereafter the gel within the leaf will besqueezed and recovered (Thompson, 1983).

In developed a method and apparatus for ex-tracting gel from Aloe vera leaves without con-taminating the gel with toxic juices, the Aloevera leaves are washed, trimmed, and fed to thehopper. The leaves will undergo to and throughmotion of a blade, which longitudinally bisectsthe leaves. The split leaves are then passedthrough pressing rollers, which advance the rindbut retain the gel that falls from the pressingrollers into a collection pan (Cottrell, 1984).

An elongated conveyor assembly on whichan Aloe vera leaf is lengthwise disposed and ad-vanced from one end of the conveyor to the oth-er end. The first and second cutting stations arespaced along the conveyor assembly. They re-move the opposite ends of an Aloe vera leaf andalso trim the serrated edges of the leaf. In addi-tion to this, the third and fourth stations are dis-posed along the conveyor assembly between thesecond station and the discharge end of the con-veyor assembly and the third station includes

structure for peeling the lower rind panel froman Aloe vera leaf whose ends and side marginalportions have been removed while the fourthstation includes structure for removing the gellayer of the leaf disposed on the upper rind pan-el thereof and exposed by the removal of thelower rind panel of the leaf (De Gray, 1986).

Aloe vera gel extracting apparatus, whichconsists of a body, transmission system, peelingdevice and a driving mechanism. The transmis-sion system comprises an upper and a lowerpart. The upper part of the system connected tothe body through the belt sheave axle at theright end and the belt sheave axle at the left endconnected to the hanger trestle in synchronousvertical movement with it. The lower part of thesystem connected to the body at both endsthrough the sheave axles. The peeling deviceconsists of an edge cutting blade and a peelingblade. The edge of cutting blade is set in the slotbetween the two groups of belt. The upper peel-ing blade is connected to the hanger trestle andthe lower peeling blade is connected directly tothe body (Xiaozhou, 2000).

Data comparison of various processing methods

The data comparison of various processingmethods and the effect on yield (total solids),aloin concentration, and the distribution of sizesof constituents (Table 3). The whole leaf meth-od can produce an Aloe juice, which is rich intotal solids however; the aloin concentration isat a very low acceptable level.

Table 2: Comparison of various processingmethods and constituents.

Method ofPreparation

pH Aloin,(ppm)

Per cent,H20

Per cent,Total Solids

Hand- filleting 4.27 6 99.25 0.48Roller 4.30 32 99.61 0.39Leaf Splitter 4.24 18 99.61 0.42Whole Leaf 4.09 1 98.62 1.38

Source : http://wholeleaf.com

Commercial production

Total process of Aloe vera



http://wholeleaf.com



In this process, aloe leaves are hand filletedby the traditional method. Then the green rindsand the mucilage pulp are processed separately.A combination of the products obtained by thesetwo procedures, produces a product called TotalProcess Aloe. Total Process Aloe contains con-siderably higher concentrations of total solids,

calcium, magnesium, and malic acid, which arevirtually free from undesirable laxativeanthraquinones. The International Aloe ScienceCouncil for certification recommends using thetotal process Aloe, which retains major portionof desirable constituents.

Figure 1: Commercial Aloe vera processing flow chart.

ALOECORP Process

The outermost matured three leaves are cutfrom every plant. The leaves are gathered in

boxes, which are transported immediately to theproduction facility. The incoming harvestedleaves are fed into the primary washer locatedjust outside the production room. The produc-





tion room is having stainless steel conveyor sys-tem that quickly moves harvested leaves fromthe primary wash tank to processing room. Theconveyors propel leaves to the mechanical leafwasher, then to the cutting area, and finallythrough the gel expulsion machines(http://www. aloecorp.com).

The other processes which are commonlyused to obtain gel in the Aloe industry is by al-cohol precipitation. In this process, 20 gallonsof Aloe gel are pumped into 100 gallon tanks,and then ethanol (80 gallons) is added to the Al-oe gel and stirred for 20-30 minutes. The alco-hol-Aloe gel mixture is then left for condition-ing for four hours. The clear supernatant thatforms is decanted or siphoned off without dis-turbing the precipitate on the bottom of the tank.The solution is then placed into centrifugingbuckets and centrifuged. The precipitate formedis collected and washed with fresh ethanol. Thisfraction is then freeze-dried.

Gel extraction process from Aloe vera pulp

The gel extraction from Aloe vera leaves,had been carried out by removing of its exudatesand its mucilage was scraped out with bluntedged knife. This mucilage was stirred vigor-ously in a blender to make it uniform. This solu-tion was strained through a muslin cloth and fil-tered. This uniform solution was extracted forcold- extracted gel (CEG) and hot extracted gel(HEG).

Cold extracted gel (CEG)

This solution was acidified with Hydro chlo-ric acid (HCL) having pH 3.50 and the crude gelwere precipitated out from the extract by addingslowly 95 % alcohol while stirring. The gel wasobtained by centrifugation.

Hot extracted gel (HEG)

Material left after passing the blended solu-tion through muslin cloth, was repeatedly treat-ed with hot water until the complete extractionsof gel was affected. The crude gel (HEG) wasprepared as described as above.

Gel extraction by Centrifugation

In this method the whole leaf after removalof the ‘peel’ the colourless hydroparenchymawas ground in a blender and centrifuged at10,000 x g for 30 min at 4 0C to remove the fi-bers. Two other patented processes to obtaingel are commonly used in the aloe industry. Thefirst is a method to extract gel polysaccharidesby alcohol precipitation (www.bonasana.com).As described in the (McAnalley, 1990) patent,20 gallons of aloe gel are pumped into 100 gal-lon tanks. Ethanol (80 gallons) is added to thealoe gel and stirred for 20-30 minutes. The al-cohol-aloe gel mixture is then left to stand forfour hours. The clear supernatant that forms isdecanted or siphoned off, without disturbing theprecipitate on the bottom of the tank. The solu-tion is then placed into centrifuging buckets andcentrifuged. The precipitate formed is collectedand washed with fresh ethanol. This fraction isthen freeze-dried. The second process is used inthe Aloe ferox industry in combination with al-cohol precipitation developed (Botha, 1994).The pulp remaining after liquidised aloe gel isfiltered is used for this process. This pulp istreated with sodium citrate that results in thefreeing of polysaccharides from calcium. Wateris added and the mixture is heated. This mixtureis then filtered, and the liquid fraction, whichcontains the calcium free polysaccharides, isknown as aloe ‘jelly’. Careful storage of gel(liquid or powder) is important to prevent lossof quality. Relative humidity and temperatureaffect product quality and shelf life (He et al.,2004). Freeze dried gel has to be packaged inairtight containers or kept under dry conditionsas it rehydrates rapidly (Femenia et al., 2003).

A developed process for extraction of gelby manual peeling of leaf and principle of cen-trifugation applied is shown in Figure 2.

Purification of Aloe vera gel

The next step in gel processing is the re-moval of cellular material from the gel. Gel fil-lets are chopped into small chips and de-pulpedusing sieves. Gel fillets can also be liquidised asin the fruit juice industry and filtered to removecellular material. After removal of the fibre, on-ly the liquid gel remains. The gel in this crude



www.bonasana.com



form is sold as a commercial product, but mayalso be mixed with activated charcoal, filterpressed, stabilized (preserved) and dried.Treatment with activated charcoal ensures that

any anthraquinone compounds in the gel areremoved. In the A. vera industry, 0.05 % w/vcharcoal is added to 2000 L gel.

Figure 2: Aloe vera Gel Extraction by Centrifugation Process Flow chart (Chandegara, 2005).

Aloe vera gel characteristics and composition

Physico-chemical properties of Aloe vera gel

Following companies had reported thephysico-chemical properties of Aloe vera gel

and shown in Table 4. This meets or exceeds thestandards established by the International AloeScience Council's (IASC) certification programfor the determination of purity.





Table 3: Fractionation of Aloe vera Gel Extrac-tion Process (Chandegara, 2005).

Aloe leaf weight 1.000 kgAloe pulp weight 0.501 kg (50.04 % of Aloe vera leaf)Crude gel recovery 0.211 kg (42.17 % of pulp)Pure gel recovery 0.106 kg (50.17 % of crude gel re-

covery)

Chemical composition of Aloe vera gel

Aloe vera gel has a biologically active poly-saccharide known as acetylated mannose, oracemannan. Acemannan is one of many saccha-rides contained in Aloe vera. Some of the othersare arabinose, cellulose, galactose, mannose,and xylose. Prostaglandins are a third importantset of compounds, and are thought to play a ma-jor role in wound healing. Aloe vera also con-tains fatty acids, enzymes, amino acids, vita-mins, minerals, and other substances.

Table 4: Physico-chemical properties of Aloe vera gel.

Test AloeCORPhttp://www. aloecorp.com

M/s Delta Internationalhttp://www.garudaint.com

Appearance Clear Yellow / Green Liquid*Absorbance @ 400nm NMT 0.500Refractive Index 1.3340-1.3355 1.33789 - 1.34390Specific Gravity 1.0030-1.0070 1.0221 - 1.0339pH Value 3.5-4.7 3.5 - 4.7Total Solids NLT 0.46% by weight

Table 5: Aloe gel composition.

Mono and polysaccharides (50-60% of solids)(Specific concentrations have not yet been determined)

Ployhexanoses Hexans Xylose Arabinose Galactose GlucoseAmino acids (ppm)

Lysine 5-6 Histadine 2.8-3.3 Arginine 4.5-5.5Threonine 5-6 Aspartic Acid 13-15 Serine 6-7Glutamic Acid 13.5-15.5 Proline 8-9 Analine 1.0-1.3Glycine 7-8 Valine 6.5-7.0 Methionine 1.5-2.0Isoleucine 3.5-4.0 Leucine 8.5-9.0 Tyrosine 2.8-3.3Pheylalanine 4.3-4.7

Vitamins (mg per 100ml)B-1 6-7 B-2 6-7 C 47-61Niacinamide 30-37 B-6 3.0-3.7 Choline 9.5-11.2

Enzymes (per 100 ml)Amylase 1100-1600 units Lipase 600-800 unitsProtein 0.11g / 100 gr Fat 0.09g / 100 grAsh 0.25% Crude fiber 0.10%Calories 3.3/100 gr

Source: http://www.garudaint.com

Quality parameters of Aloe vera gel

The quality parameters such as fiber content,viscosity, refractive index, optical density andtotal soluble solid plays an important role injudging the quality and purity of extracted gelfrom Aloe vera leaf.

A. Fiber content

The fiber content is directly related to thepurity of gel and become the criteria of efficien-cy of gel filtration unit. More fiber content, sug-gests poor filtration operation. The differencebetween crude gel recovery and pure gel recov-



http://www.garudaint.com




ery gives the amount of fiber in crude gel. It hadbeen found that the fibre content 0.074 to 0.088% of fresh weight of pulp (Wang and Strong,1993).

B. Viscosity

Viscosity of gel is very important factor fordeciding quality in terms of activities of biolog-ical compounds. The viscosity decreases as thetime passes. After harvest of Aloe vera leaf, theviscous pseudoplastic nature of Aloe vera gel,mainly due to the presence of polysaccharidescomposed of a mixture of acetylatedglucomannans is lost shortly after extraction,apparently due to enzymatic degradation(Gowda et al., 1979). These shows there aresome biological activities, which related to theviscoelastic behavior of gel.

C. Refractive index

Refractive index is the physical property ofgel determines the purity of gel as compared todouble distilled water. Gel with lowest refrac-tive index, is the best treatment for extractionprocess.

D. Optical density

Optical density is the physical property ofgel determines the purity of gel as compared todouble distilled water. Gel with lowest opticaldensity, is the best treatment for extraction pro-cess. More optical density indicates the impuri-ties in the extracted gel. The optical density of1.020 to 1.437 (abs) for Aloe vera leaves werereported (Wang and Strong, 1993).

Stabilization of Aloe vera gel

Many of the greatest benefits of Aloe veracan be lost in the processing unless great care istaken to stabilize the gel. Aloe vera gel, likemost natural juices, both fruit and vegetable, isan unstable product when extracted and is sub-ject to discoloration and spoilage from contami-nation by microorganisms. Stabilization of Aloevera gel with Sulphated polysaccharides of thered microalga Porphyridium aerugineum is car-

ried out. The solution was then stored at roomtemperature for 6 months for observations of thestructure and homogeneity of the polysaccha-rides. Addition of the algal sulphated polysac-charide resulted in a homogeneous stable prod-uct: the algal polysaccharide may inhibit degra-dation and also browning of the aloe polysac-charide (Yaron, 1992).

Product preparations from Aloe vera

Aloe vera is an industrial crop and in thefood industry it has been utilized for the prepa-ration of health food drinks, beverages like tea,milk, ice-cream and confectionary (Seoshin etal., 1995). Aloe vera gel also finds application incosmetic and toiletry industry for the prepara-tion of creams, lotions, soaps, shampoos andfacial cleaners (Grindlay and Reynolds, 1986).Choosing effective Aloe vera products can bechallenging. Once a leaf is cut, enzymes start tobreak down some of the long chain sugarswhich make Aloe vera gel an effective healingproduct, so it is important for the plant to havebeen properly handled and stabilized. Commer-cial, stabilized gel products may not work aswell as the fresh gel, but cold processing isthought to best retain the beneficial properties.Aloe vera juice is most often the form of the gelthat is used internally.

Aloe vera dessert

Basically, the ‘aloe dessert’s processing pro-cess is simple which involved sorting, grading,washing, peeling, cutting, cooking in syrup,adding flavor, packing, and pasteurizing. Themost difficult part of processing is the removalof aloe and retains its original taste and its mar-ketability. The flow chart of commercializedprocessing of Aloe vera is shown in Figure 3(Herlina, 2001).

Salve: Remove the thin outer skin and processthe leaves in a blender, add 500 units of vitaminC powder to each cup and store in refrigerator(Herlina, 2001).





Dried Juice: Aloe vera juice containing theequivalent of 360 - 900 mg of dried sap is rec-ommended by most herbalists per day (Herlina,2001).

Aloe tea and fibre tablets: Dry aloe leaves areharvested and crushed to form tea leaves. A de-licious herbal tea can be brewed. Tea leaves arepressed to form fibre tablets (Herlina, 2001).

Figure 3: Processing process of ‘Aloe vera’Dessert.

Conclusions

A review from different cited reference onprocessing of Aloe vera leaf gel has revealedsome useful information. Aloe vera plant haspotential in pharmaceutical, nutritional andcosmetic industries. The leaf of Aloe vera plantcontains biological active compounds, whichneeds careful harvesting and handling. Tem-perature is the main factor for processing of Al-oe vera and particularly gel extraction process.

The processing of Aloe vera requires criticalattention in time, temperature and sanitation.The processing and handling should be carriedout at low temperature to preserve its active in-gredients. The quality of Aloe vera gel shouldbe evaluated in terms of quality parameters likeviscosity of gel, optical density, and refractiveindex. Aloe vera gel expulsion by splitting ofleaf, roller squeezing method, crushing of wholeleaf, hand filleting methods and mechanical fil-leting methods. Aloe vera gel should be freezedried to maintain biological properties as it con-tains active compounds. After extracting the gel,the stabilization of gel is inevitable for its longduration storage and product formulations. Pre-sent processing techniques aims at producingbest quality aloe products but end aloe productscontain very little or virtually no active ingredi-ents. Hence, appropriate processing techniquesshould be employed during processing in orderto extend the use of Aloe vera gel.

Figure 4: Flow chart with mass balance forpreparation of jelly from Aloe vera gel (Anon-ymous, 2008a).





Figure 5: Flow chart with mass balance for preparation of Aloe vera gel blended RTS Beverage(Annonymous, 2008a).

References

Anonymous, 2008a. Post harvest processing ofaloe-vera leaves – a medicinal plant, AllIndia Coordinated Research Project onPost harvest Technology (Indian Council ofAgricultural Research), Annual Report,Bhubaneswar

Anonymous, 2008b. Post harvest managementof Aloe vera and aonla medicinal plants. AllIndia Coordinated Research Project onPost harvest Technology (Indian Council ofAgricultural Research), Annual Report,Jaipur





Anonymous, 2008c. Post harvest technology foraloe-vera (Aloe barbadensis miller), All In-dia Coordinated Research Project on Postharvest Technology (Indian Council of Ag-ricultural Research), Annual Report, Udai-pur

Anonymous, 2008d. Post-harvest Managementand Value-addition Department of Agricul-tural Research and Education(IndianCouncil of Agricultural Research), AnnualReport, New Delhi, pp: 80

Ashleye, F. L. 1983.Applying heat during pro-cessing the commercial Aloe vera gel. ErdeInternational 1: 40-44

Andani, S. V. 2010.Studies on high vacuumfreeze drying of Aloe vera filets and itsstorage, An unpublished M. Tech Thesis.College of Agricultural Engineering andTechnology, JAU, Junagadh.

Chandegara, V. K. 2005. Development of gelextraction process for Aloe vera leaves,An unpublished M. Tech Thesis. College ofAgricultural Engineering and Technology,JAU Junagadh.

Chang, L. X., Wang, C,, Feng, Y., Liu, Z. 2006.Effects of heat treatments on the stabilitiesof polysaccharides substances andbarbaloin in gel juice from Aloe vera Mil-ler. J Food Eng 75:245–251.

Femenia, A., Garcia P., Simal, S.,Rossello C.2003. Effect of Heat treatment and dehy-dration on bioactive polysaccharideacemannan and cell wall polymers fromAloe barbadensis Miller. CarbohydratePolymers. 51(4): 397 – 405.

Gowda, D. C., Neelisiddaiah, B., Anjaneyalu,Y. V. 1979. Structural Studies of polysac-charides from Aloe vera. CarbohydratesRes. 72: 201-205

Grindlay,D., Reynolds T. 1986. The Aloe veraphenomenon: a review of the properties andmodern uses of the leaf parenchyma gel.Journal of Ethnopharmacology, 16:117–151.

He, Q., Changhong, L., Kojo, Tian Z. 2004.Quality and safety assurance in the pro-

cessing of Aloe vera gel juice. Food Con-trol 16: 95-104 (2004).

Henry. R. 1979. An updated review of Aloevera. Cosmetics and toiletries ; 94:42-50.

Herlina, L. 2001. Incorporating private - publicrelationship into food technology develop-ment: creating added value to “Aloe vera”product SEAG Symposium, 27.-31.8.2001,Los Banos, Philippines.

Joshi, S. P. 1998. Chemical constituents and bi-ological activity of Aloe barbadensis: a re-view. Jr. of Medicinal and Aromatic PlantSciences 20:768-773

Miranda, M., Maureira, H., Rodriguez, K.,Vega- Galvez, A. 2009. Influence of tem-perature on the drying kinetics, physico-chemical properties and antioxidant capaci-ty of Aloe vera (Aloe barbadensis Miller)gel. J. Food Eng. 91(2):297 – 304

O’brien, Chantal, 2005. Physical And ChemicalCharacteristics Of Aloe Gels. An un-published M. Sc. Thesis University Of Jo-hannesburg .

Pisalkar. P. S., Jain, N.K., Jain, S.K. 2011.Osmo-air drying of Aloe vera gel cubes. JFood Sci Technol (Mar–Apr 2011)48(2):183–189.

Ramachandra, C.T.m Rao P.S. 2008. Processingof Aloe vera Leaf Gel: A Review. Ameri-can Journal of Agricultural and BiologicalSciences 3 (2): 502-510.

Ramachandra C.T., Rao P.S. 2009. Processingof Aloe vera leaf gel: a focus on the presentand innovative process technologies. In:Proc Int Conf Innovations in food and bio-process technologies, AIT Pathumthami,Thailand, 12–14 Dec, p 358–377 (2006).

Reynolds, T., Dweck, A.C. 1999. Aloe vera leafgel: a review update. Journal ofEthnopharmacology, 68: 3-37.

Segovia, P.G., Mognetti C., Bello, A. A.,Monzo, J. M. 2009. Osmotic dehydration ofAloe vera (Aloe barbadensis Miller). JFood Eng 97:154–160.

Seoshin, Y., Lee, K. S., Lee, J. S., Lee, C.H.1995. Preparation of ghurt added with Aloe





vera and its quality characteristics. J Kore-an Soc Food Nutr 24:254–260.

Shafi, N., Khan, L., Khan, G.A. 2000. Com-mercial extraction of gel from Aloe vera(L) leaves. J. Chem. Soc. 22(1): 47-49

Simal, S., Femenia, A., Llull, P., Rossello, C.2000. Dehydration of Aloe vera: simulationof drying curves and evaluation of func-tional properties. Journal of food engineer-ing. 43(2): 109-114.

Vega, A., Uribe, E., Lemus, R., Miranda, M.2007. Hot air drying characteristics of Aloevera (Aloe barbadensis Miller) and influ-ence of temperature on kinetic parameters.Food Science and Technology. 40(10):1698 – 1707.

Waller, T.A., Pelley, R.P., Strickland, F.M.2004. Industrial processing and quality con-trol of Aloe barbadensis (Aloe vera) gel. In:Reynolds (ed.) Aloes: The genus Aloe.CRC Press, London. pp. 139-205.

Wang, Y.T., Strong, K. J. 1993. Monitoringphysical and chemical properties of freshlyharvested field-grown Aloe vera leaves. Apreliminary report. Phytotherapy Research7: S1-S4

Yaron A, Cohen E, Arad (Malis), S. 1992. Sta-bilization of Aloe vera gel by interactionwith sulfated polysaccharides from red mi-croalgae with xanthan gum. J. Agrc. FoodChem. 40: 1316-1320 (1992).

Botha MC, 1994. Process for extracting poly-saccharides from plant material. SAfr.Patent ZA 941581.

Cottrell TA, 1984.Method and apparatus for ex-tracting Aloe vera gel, United States Patent4488482.(http://www.freepatentsonline.com/4488482.html)

Danhof, IE, 2000. Aloe vera, The Whole LeafAdvantage Excerpts

http://www.wholeleaf.com Accessed Janu-ary, 2000

De Gray, W. G. (1986). Aloe vera leaf proces-sor. United States Patent 4591387(http://www.freepatentsonline.com/4591387.html) Accessed July, 2007

Gilman, EF. 1999. Aloe barbadensis.http://hort.ifas.ufl.edu/shrubs/ALOBARA.PDF. Accessed 30 March 2003.McAnalleyBH, 1990. Process for preparation of aloeproducts. U.S. Patent 4 966 892.(http://www.freepatentsonline.com/4966892.html)

Moore, T. 2001. Aloe barbadensis.(http://ag.arizona.edu/pima/gardening/aridplants/Aloe_barbadensis.html) Accessed 30March 2003.

Thompson Donnie, 1983. Aloe vera plant gelseparator. United States Patent 4395942.(http://www.freepatentsonline.com/4395942.html ).

Tumlinson Larry N, 1985. Method and appa-ratus for extraction of Aloe vera gel, UnitedStates Patent45559,(http://www.freepatentsonline.com/4555987.html ).

Xiaozhou Huang, 2000. Aloe vera gel extractingapparatus, United States Patent 6117247.(http://www.freepatentsonline.com/6117247.html)

Typical composition of Aloe vera gel, GarudaInternational, Inc. 1998.http://www.garudaint.com (Accessed nJune 2004)

The Total Process Aloe vera Story. http://www.bonasana.com, (Accessed December, 2001)

Aloe vera Company, UK. Properties of Aloevera constituents.http://www.aloevera.co.uk/ (AccessedApril, 2003)



http://www.freepatentsonline.com/448848



http://hort.ifas.ufl.edu/shrubs/ALOBARA.P


http://ag.arizona.edu/pima/gardening/aridp





http://www.aloevera.co.uk/

Aloe vera L. processing and products: A review

Documents

Transcript of Aloe vera L. processing and products: A review