COLLEGE OF NATURAL SCIENCES
DEPARTMENT OF CHEMISTRY
FIELD ATTACHMENT REPORT
AT
UGANDA INDUSTRIAL RESEARCH INSTITUTE (UIRI)
BY
NIWEMUHWEZI ANSELM
12/U/946
UNIVERSITY SUPERVISOR: Assoc. Prof. Dr. STEVEN NYANZI
ORGANISATION SUPERVISOR: Mrs. NABAGGALA RITAH
A training report in partial fulfillment of the requirements for the award of the
degree of Bachelor of Science in Industrial Chemistry of Makerere University
August 2014
i
DECLARATION
I NIWEMUHWEZI ANSELM declare that the work produced in this report is from my research
and the information given by the instructors during practical sessions.
………………………………….
Signature
……………………………………
Date
ii
APPROVAL
This is to certify that this report contains a true record of what was done by NIWEMUHWEZI
ANSELM during the eight weeks of training at UIRI from 09th/06to 1st/08/2014.
Signature…………………………..
Date ……………………………….
Organization Supervisor: Mrs. Nabaggala Ritah
Signature…………………………..
Date ……………………………….
University Supervisor: Assoc. Prof. Dr. Steven Nyanzi
iii
ACKNOWLEDGEMENT
Thanks go to the almighty GOD for the gift of knowledge which has enabled me to accomplish
all these activities.
Am pleased with UIRI administration for granting me this opportunity to train from here it was a
very good experience and I managed to learn a lot of things as pertains my career.
Am so grateful and humbled by my Organization supervisor Mrs. NABAGGALA RITAH and
the staff in the chemistry laboratory for the information and knowledge they provided and other
individuals who shared their knowledge with me during this training period.
It would not be appropriate to forget my university supervisor Assoc. Prof. Dr. Steven Nyanzi for
sacrificing his time to come and supervise me and the knowledge which he shared with me
especially in report writing and project.
And finally to those who have in any way helped me either financially, academically or
otherwise to make this publication a success.
iv
PREFACE
This report covers the work which was done in industrial training from 09 th/06/2014 to
08th/08/2014 (9 weeks). It includes various food analysis tests, fruit juice tests, water analysis
tests and soap analysis tests. All the experiments were carried out using standard operating
procedures (SOPs). All the results were treated to obtain the parameter being analyzed and
recommendations given appropriately. It further includes general recommendations to the
organization and the university.
v
TABLE OFCONTENTS
DECLARATION ..............................................................................................................................i
APPROVAL .................................................................................................................................... ii
ACKNOWLEDGEMENT .............................................................................................................. iii
PREFACE ....................................................................................................................................... iv
LIST OF FIGURES ....................................................................................................................... vii
ACRONYMS ................................................................................................................................ viii
CHAPTER ONE: INTRODUCTION ............................................................................................. 1
1.1. UGANDA INDUSTRIAL RESEARCH INSTITUTE (UIRI) BACKGROUND AND
LOCATION ................................................................................................................................ 1
1.2. THE CHEMISITRY LABORATORY ............................................................................ 4
CHAPTER TWO: INSTRUMENTATION .................................................................................... 6
2.0. SOXTEC SYSTEM.............................................................................................................. 6
2.1. pH METER .......................................................................................................................... 6
2.2. MUFFLE FURNACE .......................................................................................................... 8
2.3. ATOMIC ABSORPTION SPECTROMETER (AAS) ........................................................ 8
2.4. UV/VIS SPECTROPHOTOMETER ................................................................................. 10
2.5. OVEN ................................................................................................................................. 11
2.6. WATER BATH .................................................................................................................. 12
2.7. MAJI-METER.................................................................................................................... 13
2.8. ANALYTICAL BALANCE .............................................................................................. 14
2.9. KJELTEC SYSTEM .......................................................................................................... 15
CHAPTER THREE: ANALYSIS................................................................................................. 16
3.1. FOOD ANALYSIS ............................................................................................................ 16
EXP 1: DETERMINATION OF ASH CONTENT ............................................................... 16
EXP 2: DETERMINATION OF FAT CONTENT USING SOXHLET METHOD............. 19
EXP 3: DETERMINATION OF MOISTURE CONTENT IN FOOD SAMPLES .............. 23
EXP 4: DETERMINATION OF VITAMIN A IN FORTIFIED FLOUR ............................ 27
EXP 5: DETERMINATION OF β-CAROTENE .................................................................. 29
PROXIMATE ANALYSIS OF FLOUR SAMPLE .............................................................. 31
3.2. TOUR TO OTHER PRODUCTION DEPARTMENTS IN THE INSTITUTE ................ 32
vi
A TOUR TO THE DAIRY PROCESSING PLANT ............................................................ 32
A TOUR TO THE FOOD PROCESSING PLANT .............................................................. 33
A VISIT TO THE JUICE PROCESSING PLANT ............................................................... 34
3.3. ANALYSIS OF FRUIT JUICES ....................................................................................... 35
EXP 6: DETERMINATION OF VITAMIN C ..................................................................... 35
EXP 7: DETERMINATION OF TOTAL TITRATABLE ACID IN FRUIT JUICES ......... 39
EXP 8: PROTEIN CONTENT DETERMINATION IN FRUIT JUICES ............................ 41
3.4 SOAP ANALYSIS .............................................................................................................. 44
EXP 9: DETERMINATION OF pH VALUE OF SOAP SAMPLE ..................................... 44
EXP 10: DETERMINATION OF INORGANIC SALTS ..................................................... 44
3.5. WATER ANALYSIS ......................................................................................................... 47
CHAPTER FOUR: RECOMMENDATIONS, CONCLUSION AND REFERENCES .............. 48
4.1. LIST OF SKILLS ACQUIRED ......................................................................................... 48
4.2. RECOMMENDATIONS ................................................................................................... 48
4.2. CONCLUSION .................................................................................................................. 49
4.3. REFERENCES................................................................................................................... 50
APPENDIX ................................................................................................................................... 51
STANDARD OPERATING PROCEDURES (S.O.PS) ........................................................... 51
WASTE MANAGEMENT ....................................................................................................... 53
vii
LIST OF FIGURES
Figure 1: UIRI location and UIRI main block ................................................................................ 2
Figure 2: A representation of Soxtec System ................................................................................. 6
Figure 3: A representation of pH meter .......................................................................................... 7
Figure 4: A representation of Muffle furnace ................................................................................. 8
Figure 5: A representation of Atomic Absorption Spectrum (AAS) ............................................ 10
Figure 6: A representation of UV/VIS spectrophotometer ........................................................... 11
Figure 7: A representation of an Oven.......................................................................................... 12
Figure 8: A representation of a water bath.................................................................................... 13
Figure 9: A representation of Maji-Meter..................................................................................... 13
Figure 10: A representation of an Analytical balance................................................................... 14
Figure 11: A representation of a Kjeltec system........................................................................... 15
viii
ACRONYMS
1. UIRI……………. Uganda Industrial Research Institute
2. UNBS …………..Uganda National Bureau of Standards
3. RSD…………….. Relative Standard Deviation
4. SD………………. Standard Deviation
5. pH………………...Potential of hydrogen
6. ID ………………...Identification
7. AR……………… Analytical Reagent
8. QC……………….. Quality Control
9. QA……………….. Quality Assurance
10. M………………... Molarity
11. N………………….. Normality
12. SOPs…………… standard operating procedures
13. Psig …………….pounds per square inch gauge
1
CHAPTER ONE: INTRODUCTION
1.1.UGANDA INDUSTRIAL RESEARCH INSTITUTE (UIRI) BACKGROUND AND
LOCATION
UIRI was formally established by an Act of Parliament in 2002 by H.E. the President to the
Act on 30th July 2003. It is a progeny of the East African Industrial Research Organization
(ESIRO) of the non-operational East African Community (EAC)]. After the end of the then
EAC in 1977, the three member states continued with the splintered Industrial Research
Organizations, and hence was born:
Kenya Industrial Research and Development Institute (KIRDI)
Tanzania Industrial Research and Development Institute (TIRDI)
Uganda Industrial Research Institute (UIRI)
With Uganda's economic dislocation of the 70s and 80s, UIRI did not become fully
operational until 1997 when, with a grant from the Government of People's Republic of
China (GPRC) a campus was built and some technologies for pilot plants installed. The
formal handover of the modern facility to Uganda Government was done in the year 2000.
UIRI's mandate is to engage in activities that will lead to rapid industrialization of Uganda.
UIRI's Vision and Mission
To be the model institution and regional center of excellence, for incubation of industry and
pioneering industrial Research and Development activities that could elevate the level of
technology in Uganda and the region.
UIRI's mission:
1. To improve capacity and competence of indigenous entrepreneurs in undertaking viable
industrial production processes and in their ability to produce high quality marketable
products.
2. To provide demand driven Scientific Industrial Research and Development and
Internationally competitive technical services that will lead to rapid industrialization for the
benefit of the people of Uganda.
UIRI's Mandate and Objectives
UIRI's mandate derived from the statute that established the institution is to undertake
applied research, and develop and acquire appropriate technology in order to create a strong,
effective and competitive industrial sector for the rapid industrialization of Uganda.
2
In order to fulfill its mandate, UIRI has established the following corporate objectives:
1. To undertake Applied Industrial Research for the development of optimal production
processes for Uganda's nascent industry.
2. To develop and/or acquire appropriate technology in order to create a strong, effective, and
competitive industrial sector for the rapid industrialization of Uganda.
3. To provide the necessary expert input towards Government Development Initiatives.
Location of the organization
Uganda Industrial Research Institution is located in Nakawa Industrial Area, Plot 42A
Mukabya Road, P .O. Box 7086, Kampala Uganda. Website http://www.uiri.org
Figure 1: UIRI location and UIRI main block
Organization and Governance of UIRI
UIRI is governed by a Board of Directors, with an Executive Director as the Chief Executive
responsible for day-to-day operations and policy implementation. The departmental structure
is comprised of the following organizational units:
1. Administration
Responsible for the welfare of staff, the operability of facilities, financial diligence, logistical
optimality, and inter-departmental coordination
UIRI boasts of a competent well-trained management team. The core management team, led
by the Executive Director is comprised of a Deputy Executive Director, Administrative
Officer, Chief Technical Advisor, Research Officers (Heads of Departments). Current staff
totals 50.
3
The combined experience in Training, Research, Business Analysis, and Engineering
Operations is in excess of 145 years, ranging from a low of 2 to a high of 29 years, and
averaging around 12 years.
A significant number of the management team has handled several projects of small, medium
to large, both in size and complexity.
1. Food Science and Technology
Undertakes research in industrial processes and technology for adding value to food products
The division is responsible for running pilot plants for processing dairy, meat, bakery, fruits
and vegetable products. Although the products from the pilot plants are available for sale to
the public, the cardinal role of the pilot plants is to train entrepreneurs and others from
tertiary and university institutions.
2. Ceramics
Responsible for research, design and production of high quality ceramics products
Department maintains a showcase at the Institute and some of their products are available for
sale to the public.
3. Training
Coordinates a spectrum of training programs from basic to advanced skill levels, and from
the starting to the fully formed entrepreneur Most training is conducted in-house and
programs are run by the staff of the institute.
4. Analytical Laboratories
Support internal research and offer services to the public in such areas as product analysis -
content and context, physical and chemical properties, or any analytical service that the client
might desire. Laboratories are divided into Analytical Chemistry, Microbiology and Mineral
laboratory.
5. Engineering and Manufacturing
This runs a maintenance engineering workshop as well as a carpentry shop, Provides all
engineering and technical maintenance services to the entire Institute, and coordinates any
engineering/technical services that may be contracted from outside.
Operations and Functions
In fulfillment of its mandates, UIRI performs the following functions:
1. Identify and develop appropriate technologies and processes for the exploitation of our
nation's natural resources.
4
2. Upgrade and strengthen the existing indigenous technologies through basic and applied
research.
3. Set-up pilot plants to demonstrate the operation and benefits of new technologies, and
otherwise perform the role of an incubator for new industrial enterprises.
4. Design, develop and adapt machinery, tools, equipment and instruments suitable for small-
scale enterprises, especially in rural areas.
5. Maintain a comprehensive data bank on industrial research, technologies, materials and
products.
6. Facilitate the provision of technical advice and other assistance to existing enterprises in
order to improve their competences and their operational efficiencies.
7. Provide research findings to entrepreneurs to assist them in setting up new projects.
8. Collaborate with other organizations, both nationally and internationally, to create
synergies to improve knowledge, networking and capacity building for the benefit of our
client base and for rapid industrialization through technology transfer.
9. Serve as a production technology reference center.
1.2.THE CHEMISITRY LABORATORY
EQUIPMENT SAFETY GUIDELINES
Do not operate any equipment without permission
Carefully follow operating instructions when handling a given equipment
Switch off equipment after use
Report equipment malfunction immediately
Do not operate faulty equipment
HOUSE KEEPING
Before starting any task, the following are put into consideration;
All necessary things (reagents, equipment) should be returned to their places and only
required things are brought.
The work place should be cleaned
After doing any task, the following are considered;
5
Collecting and cleaning the apparatus
All apparatus should be returned to storage
Cleaning the work place
At the end of the day, all apparatus should be returned to the place of storage and
work place cleaned and organized.
LABORATORY SAFETY GUIDELINES
Always wear gloves when handling corrosive substances
Keep your place and your place of work tidy
Clean up any spillages, acid or alkaline spillages should be neutralized first before
cleaning them up
Label reagents, samples, drawers clearly
Always use the fume hood when handling highly toxic substances
Always screw reagent bottle caps and chemical bottle tops tightly
Keep chemicals, apparatus and equipment in such a way that they will not fall down
Do not eat, drink or smoke in the laboratory
Do not pour corrosive substances into the sink but pour in glass dispersal bottles or
discard bottles
Do not add water to acid but acid to water
Do not pipette poisonous or hazardous solutions using your mouth, always use pipette
fillers
Do not handle reagent bottles by their necks
Report any accident that occurs immediately
Never leave potentially hazardous work unattended to
6
CHAPTER TWO: INSTRUMENTATION
2.0. SOXTEC SYSTEM
This was used to analyze fat and oils in the samples. The Soxtec system provides a means of
safe and fast solvent extraction of foods, feeds and many more matrices. Extraction is used to
isolate soluble matter such as crude fat, additives, pesticides and minor constituents from
complex materials.
Extraction analysis is traditionally based on the Soxhlet principle because of its worldwide
accuracy and reproducibility. However convectional Soxhlet analysis involves tedious and
time consuming manual work and explosion risks. The patented design of Soxtec system HT
2 makes it possible to perform extractions using a wide range of solvents in a quicker, safer
and more economical way compared to the Soxhlet extractions. The combination of the
Soxtec extraction technique and wide range of solvent use makes the HT 2 Soxtec system a
flexible and powerful tool in the analysis of soluble compounds from materials such as; food,
feed, chemical technical products and pharmaceuticals.
Figure 2: A representation of Soxtec System
2.1. pH METER
A pH meter is an electronic device used for determining the acidity or alkalinity of a solution
(though special probes are sometimes used to measure the pH of semi-solid substances). A
pH meter consists of a special measuring probe (a glass electrode) connected to an electronic
meter that measures and displays the pH reading. At the bottom of the probe there is a bulb
which is the sensitive part of the probe as it contains a sensor. For every precise work, the pH
meter should be calibrated before each measurement. For normal use, verification should be
done at the beginning of each day using standard buffers of known pH. This is so because the
glass electrode does not give a reproducible electromotive force over long periods of time.
Verification should be done with at least two standard buffer solutions that span the range of
values to be measured.
7
Operation
The solution whose pH is to be measured is put into a container and the probe is dipped into
it. When the values on the meter screen have stabilized, a button with the label “READ” is
pressed, the pH and the temperature are recorded.
After each single measurement, the probe is rinsed with distilled water or deionized water to
remove any traces of the solution, cleaned with tissue to absorb any remaining water that
could dilute the sample and hence alter the reading, and then quickly immersed in another
solution.
Note: The probes should be ocassionary cleaned (at least once a month) and this can be done
using pH electrode cleaning solution; generally a 0.1 M solution of hydrochloric acid is used
(having a pH of one). Alternatively, a dilute solution of ammonium fluoride (NH4F) can be
used.
Figure 3: A representation of pH meter
8
2.2. MUFFLE FURNACE
A muffle furnace is used for providing extremely high temperature for example in
determination of ash content in a given sample.
PROCEDURE FOR OPERATION OF MUFFLE FURNACE
1. Plug equipment into power supply
2. Turn on the ‘on/off’ button on the front panel of the equipment.
3. Press ‘T’ on the front panel
4. Move cursor (in form of a dot) using the arrows on the front panel while adjusting
temperature by changing the number using the up ↑ and down ↓ arrows.
5. After setting the temperature move cursor at end of set temperature then press ‘start’.
Figure 4: A representation of Muffle furnace
2.3. ATOMIC ABSORPTION SPECTROMETER (AAS)
The A Analyst 400 Atomic Absorption Spectrum is a double –beam atomic absorption
spectrometer for flame or manual mercury hydride determinations. It is a sophisticated
analytical system capable of performing automated single element determinations.
OPERATING PROCEDURE
1. Read the safety information before you operate the system.
2. Turn on the Acetylene gas and adjust the outlet gauge pressure to the recommended
value of 14 Psig. NEVER allow the outlet gauge pressure to exceed 103kPa (1.03 bar,
15 Psig); acetylene can explode spontaneously above this pressure.
3. Turn on the Air compressor and adjust the outlet gauge pressure to the recommended
range of 70 to 80 Psig.
4. Open the lamp door and install the required lamp for the analyte element. Please note
the position for mercury, its either position 1 or 2.
9
5. Switch on the spectrometer using the operational on/off switch. Close the lamp door
and wait for the spectrometer to complete initialization for about 5 minutes.
6. Activate the WinLab32 for AA software on the computer. Leave it to complete
initialization for about 2 minutes.
7. In WinLab32 for AA software select the Method icon and define the element of
interest. The wavelength and slit fields will automatically have the correct values.
8. Still under the Method icon, click “setting” and enter the current which is set to
10Afor all other elements except for Mercury which is 15A. Click “calibration” and
then select standard calibration, enter name of the Blank, standards and their
respective concentrations. Go to the “FILE icon” then select method, name the
method and save it.
9. In WinLab32 for AA software select the Sample info icon and then enter the sample
ID. Go to the “FILE icon” then select sample info, name the file and save it.
10. In the Flame Control window, select the on side of the flame On/Off switch to light
the flame and leave to initialize for 2 minutes.
11. Select “Manual window” and enter the name of the result file where you want to
save your results. OR you can create new folder for the results and save it. Select save
data and print log in the Manual window.
12. Load the Blank sample first onto the equipment, wait for 30 seconds and then select
“Analyze Blank” on the Manual window. This will activate analysis of the Blank.
Do not remove the Blank until “idle” is indicated on the window.
13. Load the standard samples onto the equipment and follow the order as entered in the
method icon (Standard concentration), wait for 30 seconds and then select “Analyze
Standard” on the manual window. This will activate analysis of the standard. Follow
the procedure for all the standards but first rinsing with blank before each analysis.
14. After analyzing the standards, Load the test sample on the equipment and follow the
order as entered in the sample info window, wait for 30 seconds and then select
“Analyze sample” on the manual window. Follow the same procedure for all
samples but first rinsing with blank before each analysis.
15. You can select the Results icon to view the results.
16. After analysis of the samples, select the Flame Control window select the off side of
the Flame On/Off switch to turn off the flame.
17. Turn off the acetylene gas by closing the valve. Wait for 2 minutes and then select the
‘Bleed gases” on the Flame Control window. Do it at least 2 times.
18. Turn off the WinLab32 for AA software and then switch off the spectrometer by
using the operational on/off switch. Switch off any other accessories.
10
NOTE
Make sure that the sample loop is always immersed in de-ionized water.
Dispose of hazardous or corrosive solutions properly and refer to your local safety
regulations for proper disposal procedures
Figure 5: A representation of Atomic Absorption Spectrum (AAS)
2.4. UV/VIS SPECTROPHOTOMETER
For a beam of light incident on the sample part of the light is absorbed and the other emitted
using the principle of beer’s law samples can be analyzed.
Procedure for operation of UV/VIS spectrophotometer
Switch on power supply, switch on power stabilizer, turn on the UV/VIS
spectrophotometer using the green button on the top of the equipment and finally
switch on the computer.
Wait for equipment to initialize until it shows previously used method /wavelength.
On the computer programs is UV-win lab under which you should click Lambda Bio
20. The method window will open up.
Select method to be used for example scan, or Time drive.
Under the selected method set the required parameters like wavelength, number of
references, or number of samples.
Fill blank sample in one of the two marching Cuvettes (cells) and insert it in one of
the porches inside the spectrometer where light beams pass.
Click start. The equipment will ask for next sample blank so insert next sample blank
in remaining porch where light beam passes
11
Taking an example of the concentration method the equipment will then ask for
consecutive references /standards.
Figure 6: A representation of UV/VIS spectrophotometer
2.5. OVEN
Connect the power cable of the oven to the power outlet.
Ensure that the temperature setting potentiometer is set to a minimum.
Switch the On/Off key to the ‘ON’ position.
Adjust the temperature setting potentiometer to set the desired temperature.
Wait until the orange indicator lamp starts flashing continuously and the thermometer
is indicating the desired temperature, to insert items into the oven.
Close oven door and leave items inside for the desired period of time.
Remove the items from the oven, once the desired period of time has elapsed.
Set the temperature setting potentiometer to a minimum.
Switch the On/Off Key to the ‘OFF’ position.
12
Figure 7: A representation of an Oven
2.6. WATER BATH
On heating, water increases in temperature and on reaching 100oC it boils hence heating up
whatsoever is in its contact
Procedure for operation of water bath
Check that the level of water is above the tray inside the water bath.
Plug equipment onto power supply
Press red button on front panel to switch on power in the equipment.
Set required temperature by pressing the “+” or “-” buttons corresponding to the
position of number. The green light will be lit up to show that equipment is gaining
the set temperature.
13
Figure 8: A representation of a water bath
2.7. MAJI-METER
The Maji-Meter is capable of measuring up to 11 parameters in the field simply by
submerging the probe into a water course and using the control unit to run the test and view
results. It was used to determine pH, Turbidity, electrolytic conductivity (EC), dissolved
oxygen (DO), total dissolved solids (TDS), altitude, latitude and longitude of water samples
in the field. An integrated GPS system allows users to identify exactly where results were
taken and record other location information, providing more informative analyses. The Maji-
Meter can be used to analyze both surface and ground water in a variety of settings such as
rivers, lakes, industrial systems, wells and bore-holes.
Figure 9: A representation of Maji-Meter
14
2.8. ANALYTICAL BALANCE
Procedure for daily use
i. Press ON/OFF button once to turn on the instrument
ii. Place a weigh boat on the balance pan. iii. Press the Tare control to zero the balance.
iv. Wait a few seconds until the reading has stabilized until the small box goes away v. Add the substance or chemical to be weighed. vi. Wait until the reading stabilizes and the small box goes away.
vii. Record the results.
Maintenance
i. The balance is calibrated annually with a standard set of weights by UNBS
ii. At the first time of weighing every day, a standard mass (5g) is used for verification. This helps to tell the need and agency for calibration. This acts as a quality control
(QC)measure Figure 10: A representation of an Analytical balance
15
2.9. KJELTEC SYSTEM
The Kjeltec Distillation Unit provides a simple and reliable solution for safe and semi-
automatic distillation. The procedure for its use is elaborated in the experiment for protein
digestion.
Figure 11: A representation of a Kjeltec system
16
CHAPTER THREE: ANALYSIS
3.1. FOOD ANALYSIS
EXP 1: DETERMINATION OF ASH CONTENT
Ash content is a measure of minerals in the food. Ash refers to the inorganic components
remaining after either ignition or complete oxidation of organic matter in a foodstuff. The
importance of Ash in Food analysis is to proximate the nutritional evaluation and it is the
first step in the preparation of food sample for specific elemental analysis.
Mineral content is a measure of the amount of specific inorganic components present within
a food, such as Ca, Na, K and Cl. Determination of the ash and mineral content of foods is
important for the following reasons:
Nutritional labeling: The concentration and type of minerals present must often be
stipulated on the label of a food.
Quality: The quality of many foods depends on the concentration and type of
minerals they contain, including their taste, appearance, texture and stability.
Microbiological stability: High mineral contents are sometimes used to retard the
growth of certain microorganisms.
Nutrition: Some minerals are essential to a healthy diet (e.g. Calcium, phosphorous,
potassium and sodium) whereas others can be toxic for example lead.
There are two types of ashing used that is;
1) Dry Ashing: it refers to the use of a muffle furnace that is capable to maintain
temperatures of 500-600°C. Water and volatiles are vaporized and organic substances
are burned in the presence of oxygen in air to CO2, and oxides of N2. Most minerals
are converted to oxides, sulfates, phosphates, chlorides, and silicates.
2) Wet Ashing; this is a procedure for oxidizing organic substances by using acids and
oxidizing agents or their combinations. Minerals are solubilized without
volatilization. Wet ashing is often preferable than dry ashing as a preparation for
specific elemental analysis.
PROCEDURE
The weight of the crucible was first determined and recorded. 5g sample were weighed into a
tarred crucible and then heated first to evaporate the volatile matter. The crucibles were
placed in muffle furnace. Their order of arrangement in the furnace was recorded. The
furnace was ignited for 6 hours at 550oC.The muffle furnace was turned off and later opened
when the temperature had dropped to 250oC. The sample in crucible should be completely
white with no black spots. Using safety tongs, the crucibles were removed, re-labeled using
17
the recorded arrangement and transferred to a desiccator and allowed to cool prior to
weighing. After cooling the sample was weighed and results recorded in the work book.
NOTE
1) If carbon is still present following initial incineration, add several drops of water or
nitric acid; the sample should be re ashed. If the carbon persists, such as with high
sugar samples follow this procedure;
Suspend the ash in water and filter through ash less filter paper because this residue tends
to form a glaze. Dry the filtrate Place paper and dried filtrate in muffle furnace and re dry
2) Warm crucibles will heat air in the desiccator. With hot samples, a cover may bump
to allow air to escape. A vacuum may form on cooling. At the end of the cooling
period, the desiccator cover should be removed gradually by sliding to one side to
prevent a sudden in rush of air. Covers with ground glass sleeve or fitted for a rubber
stopper allow for slow release of vacuum.
TABLE OF RESULTS
Sample ID: 166/2014
Replicate 1 Replicate 2 Replicate 3
Weight of crucible (g) 61.9818 67.8837 67.1456
Weight of sample (g) 5.0021 5.0057 5.0021
Weight of sample + crucible (g) 62.2274 68.1269 67.3158
TREATMENT OF RESULTS
Weight of Ash = (Weight of Ash + crucible) - weight of crucible
Percentage of Ash = weight of Ash
weight of sample x 100%
Replicate 1
Weight of Ash = (62.2274 – 61.9818)
= 0.2456g
Percentage of Ash = 0.2456g
5.0021g x 100%
= 4.91%
18
Replicate 2
Weight of Ash = (68.1269– 67.8837)
= 0.2432g
Percentage of Ash = 0.2432g
5.0057g x 100%
= 4.86%
Replicate 3
Weight of Ash = (67.3158– 67.1456)
= 0.1702g
Percentage of Ash = 0.1702g
5.0021g x 100%
= 3.40%
Calculation of mean percentage
Mean =∑𝒙
𝒏 =
(𝟒.𝟗𝟏+ 𝟒.𝟖𝟔+𝟑.𝟒𝟎)
𝟑= 𝟒. 𝟑𝟗%
Calculation of standard deviation
Percentage X Deviation (X— X ) Square deviation (X— X )2
4.91 0.52 0.2704
4.86 0.47 0.2209
3.40 -0.99 0.9801
∑ (X— X )2 = 1.4714
Standard deviation = √(∑(X— X )2)
𝒏−𝟏
=√(1.4714)
𝟐= 𝟎. 𝟖𝟓𝟕𝟕%
19
Calculation of Relative standard deviation (RSD)
RSD = 𝑺𝒕𝒂𝒏𝒅𝒂𝒓𝒅 𝒅𝒆𝒗𝒊𝒂𝒕𝒊𝒐𝒏
𝒎𝒆𝒂𝒏 =
(0.8577)
4.39 x 100%
RSD = 19.54%
RECOMMENDATION
The experiment should be repeated because the relative standard deviation is greater than 5%
(RSD > 5%)
EXP 2: DETERMINATION OF FAT CONTENT USING SOXHLET METHOD
Total Fat refers to the sum of triglycerides, phospholipids, wax ester, sterols and minor
amount of non-fatty materials
Apparatus
Extraction unit 1043 Soxtec System HT6 - service unit 1046, Soxtec System HT6
Extraction cups
Cup holder
Tongs for extraction cups
Thimbles and adapters
Reagents - petroleum ether
PROCEDURE
PREPARATION OF ALUMINIUM CUP
The aluminium cup was first washed with acetone and rinsed with distilled water
The aluminium cup was dried in an oven for 5 hours.
The dried aluminium cups were kept in a desiccator ready for use.
PREPARATION OF SAMPLE
2g of dried sample were weighed out accurately into a cellulose thimble of already
determined dry weight. Care was taken not to spill sample powder outside thimble. A
thimble was then placed in an aluminium cup.
SETTING UP THE EXPERIMENT
A thin layer of cotton wool was placed on top of the sample in the thimble.
The adapter was inserted on top of cotton wool in the thimble.
20
On the extraction unit, the adjustable nob of each side of the unit was raised upward
and the thimbles (for two samples) were attached in their positions tightly.
The knobs were lowered to allow thimbles to lift up and give space for fixing the
aluminium cups.
60ml of petroleum ether were measured in a measuring cylinder and transferred to
each of the aluminium cups.
The rubber ring was placed on each of the aluminium cups.
Each cup was placed on top of the extraction hot plates and then adjusted using the
lower knobs so as to attach each cup under its corresponding thimble as labeled, that
is, 1 for 1, or 2 for 2.
The upper adjustable knob was raised in the boiling position so as to allow the
thimble units get inserted into the petroleum ether (solvent) in each aluminium cup
NOTE
1. Care is taken to ensure that all fittings are air tight
2. Aluminium cups must not be interchanged
The tubings connected from the service unit and tap (water) to extraction unit
were kept in position as required and air tight.
Tap water was opened, and confirmed that it flows to the condensing unit and
returns to the sink through drain.
STARTING TO RUN THE EXPERIMENT (boiling)
The mains of the service unit was switched on.
The extraction temperature was adjusted to 1000C and set the safety knob to
1500C.
The extraction process was monitored. Condensation of the solvent was seen
rolling down back to the sample through the extraction unit taps in open position.
When condensate was seen rolling down (checked by closing and opening taps
temporarily and leaving open), the timer was turned in the clockwise direction to
the 30minute mark so that boiling should run for 30minutes.At the end of boiling
time, timer rings while returning back to the 60/0 minutes mark.
RINSING
At the end of boiling, thimbles were raised out of the solvent by pressing the
upper buttons to the RINSE position.
Timer was immediately set to 30 minutes.
At the end of the rinse time (30 minutes), taps of extraction unit were closed to
stop solvent from condensing through the thimbles.
21
Solvent was left to condense and collect above the taps at the base of the
condenser. This process was left to run until no more solvent was condensing.
DRYING RESIDUE AND EVAPORATION OF SOLVENT
The compressed air valves were raised upward to open them (on the extraction
unit).
On the service unit, compressed air supply was switched on and set timer15
minutes.
NOTE: compressed air facilitates drying of the residue in the thimbles and evaporation
of the solvent further from the thimbles and aluminium cups
CLOSING DOWN
At the end of drying, compressed air was switched off, air taps closed, power
switched off, and the flow rate of the cooling water reduced.
The apparatus was left to cool for 15 minutes
Cooling water was turned off completely.
Aluminum cups were removed carefully (should be having oil).
The cups were put in the oven, set at 1050C, and left to dry for two hours.
At the end of 2hours, oven was switched off and left to cool to 400C without
opening its door.
At 400C, the cups were removed, put in the desiccator, and left to cool in there for
exactly 30 minutes.
At the end of 30 minutes, each cup was weighed, obtaining weight W3
The percentage fat content in food samples was determined using the following
formula;
% fat = (W3 − W2)
W1 x 100
Where W3= Weight of extraction cup + residue weight (g)
W2 = Weight of extraction cup (g)
W1 = original sample weight (g)
TABLE OF RESULTS
Dry weight of cup (W2) (g) No.1 No.2
38.7855 38.6098
Weight of the sample (W1) (g) 3.0094 3.0016
Weight of cup + residue weight (W3) (g) 39.1003 38.8828
Weight of Oil (g) 0.3148 0.273
22
TREATMENT OF RESULTS
% fat = Weight of Oil
Weight of Sample x 100%
Replicate 1
% fat = 0.3148
3.0094 x 100%
% fat = 10.46%
Replicate 2
% fat = 0.273
3.0016 x 100%
% fat = 9.10%
Calculation of mean percentage
Mean =∑𝒙
𝒏 =
(10.46+9.10)
2= 9.78%
Calculation of standard deviation
Percentage X Deviation (X— X ) Square deviation (X— X )2
10.46 0.68 0.4624
9.78 0.68 0.4624
∑ (X— X )2 = 0.9248
Standard deviation = √(∑(X— X )2)
𝒏−𝟏
=√(0.9248)
𝟐−𝟏= 𝟎. 𝟗𝟔𝟏𝟕%
Calculation of Relative standard deviation (RSD)
RSD = 𝑺𝒕𝒂𝒏𝒅𝒂𝒓𝒅 𝒅𝒆𝒗𝒊𝒂𝒕𝒊𝒐𝒏
𝒎𝒆𝒂𝒏 =
(0.9617)
9.78 x 100%
RSD = 9.83%
23
Recommendation
The RSD is greater than 5% because one of the sides of the Soxtec machine leaks so the
petroleum ether used for extraction leaks which leads to low mass of the fat extracted. Thus
replicate 1 result is the correct one.
EXP 3: DETERMINATION OF MOISTURE CONTENT IN FOOD SAMPLES
PRINCIPLE
Moisture determination is one of the most important analyses performed on a food sample
and yet one of the most difficult from which to obtain accurate and precise data.
The dry matter that remains after moisture removal is referred to as Total solids. This
analytical value is of great economic importance to a food manufacturer because water is
inexpensive filler.
Moisture is a quality factor in the preservation of some food products and affects the food
stability for example, in dried milks and dehydrated vegetables and fruits.
Computation of nutritional value of foods requires that you know the moisture content.
Moisture data are used to express results of other analytical determinations on a uniform
basis (such as, dry weight basis)
EQUIPMENT AND MATERIALS
Usual laboratory apparatus not otherwise specified, and the following items
o Electric drying oven
o Petri dishes
PREPARATION OF GLASSWARE
The glassware were washed and rinsed with distilled water.
Dry glassware was placed in electric oven for 4 hours at1050c
Glassware were removed from the oven and then cooled in the desiccator for 30
minutes
After 30 minutes, the glassware was weighed and recorded the weights respectively.
24
PROCEDURE
5g of sample was weighed into the petri-dish. The sample was heated in an electric oven for
4hours set at 1050C. After, the sample was removed from the electric oven then transferred to
the desiccator to cool to room temperature for 30 minutes. After the sample and the petri-dish
were weighed results recorded.
The moisture content calculations were determined using the formula
%moisture = 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑤𝑒𝑡 𝑠𝑎𝑚𝑝𝑙𝑒−𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑟𝑦 𝑠𝑎𝑚𝑝𝑙𝑒
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑤𝑒𝑡 𝑠𝑎𝑚𝑝𝑙𝑒 ×100
% Total solids =𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑟𝑦 𝑠𝑎𝑚𝑝𝑙𝑒
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑤𝑒𝑡 𝑠𝑎𝑚𝑝𝑙𝑒 ×100
PRECAUTIONS TAKEN
These were taken to minimize unintended moisture losses or gain that occurs during these
steps. Any exposure of the sample to the open atmosphere should be as short as possible.
Any heating of the sample during grinding should be as short as possible. Head space in the
sample storage container should be minimal because the moisture is lost from the sample to
equilibrate the container environment against the sample.
TABLE OF RESULTS
Sample ID: 166/2014
Replicate 1 Replicate 2 Replicate 3
Weight of dry petri dish (g) 98.3656 86.3502 95.1140
Weight of sample (g) 5.0008 5.0002 5.0020
Weight of sample + dish (g) 102.8194 90.8057 99.5736
Sample ID: 167/2014
Replicate 1 Replicate 2 Replicate 3
Weight of dry petri dish (g) 95.0000 90.1142 90.1140
Weight of sample (g) 5.0011 5.0012 5.0024
Weight of sample + dish (g) 99.4652 94.5803 94.5821
25
TREATMENT OF RESULTS
Weight of Dry sample = (Weight of dry sample + dish) - weight of dry petri dish
Replicate 1
Weight of dry sample = 102.8194 – 98.3656
= 4.4538g
Percentage moisture = weight of wet sample−weight of dry sample
weight of wet sample x 100%
Percentage total solids = weight of dry sample
weight of wet sample x 100%
Percentage moisture =(5.0008 −4.4538)g
5.0008g x 100%
= 10.94%
Percentage total solids = 4.4538
5.0008 x 100%
= 89.06%
Replicate 2
Weight of dry sample = 90.8057 – 86.3502
= 4.4555g
Percentage moisture =(5.0002 −4.4555)g
5.0002g x 100%
= 10.89%
Replicate 3
Weight of dry sample = 99.5736 – 95.1140
= 4.4596g
Percentage moisture =(5.0020 −4.4596 )g
5.0020g x 100%
= 10.84%
26
Calculation of mean percentage
Mean =∑𝑥
𝑛 =
(10.94+10.84+10.89)
3= 𝟏𝟎.𝟖𝟗%
Calculation of standard deviation
Percentage X Deviation (X— X ) Square deviation (X— X )2
10.94 0.05 0.0025
10.84 -0.05 0.0025
10.89 0 0
∑ (X— X )2 = 0.005
Standard deviation =√(∑(X— X )2)
𝒏−𝟏
=√(0.005)
𝟐= 𝟎.𝟎𝟓%
Calculation of Relative standard deviation (RSD)
RSD = 𝑆𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛
𝑚𝑒𝑎𝑛 =
(0.05)
10 .89 x 100%
RSD = 0.46%
27
EXP 4: DETERMINATION OF VITAMIN A IN FORTIFIED FLOUR
METHOD: UV method
REAGENTS
Sodium chloride AR
2-propanolAR
Dichloromethane AR
n-heptane AR
PROCEDURE
Flour (27.0081g) was weighed into a 500ml Erlenmeyer conical flask, distilled water (100ml)
added and shaken vigorously for 5 minutes. 2-propanol (80ml) was added to the flask and
shaken vigorously for 5 minutes. n-heptane (50ml) was also added to the flask and shaken
vigorously for 5 minutes. Sodium chloride (5g) was then added to improve the separation and
then shake slightly. The solution in the flask was kept in dark room for 10minutes for
separation of phases. The top most organic phase was carefully removed using a Pasteur
pipette into a 50ml amber volumetric flask and made up to the mark using dichloromethane.
The contents in the 50ml amber volumetric flask were transferred into a 50ml centrifuge
tube. The tubes were placed into a centrifuge bucket and the centrifuge set at 1000 RPM for
ten minutes. After the tubes were removed from centrifuge and rapped using aluminium foil
to protect them from light. Using a Pasteur pipette the organic phase was carefully removed
and transferred into the UV spectrophotometer cuvettes and the absorbance read at 325nm.
Dichloromethane was used as the blank.
RESULTS AND TREATMNET
Sample ID 104/2014
Weight of sample (g) Absorbance
27.0081 0.8105 0.8123 0.8110
Sample ID 105/2014
Weight of sample (g) Absorbance
27.0084 0.4498 0.4494 0.4493
28
Sample ID 108/2014
Weight of sample (g) Absorbance
27.0063 0.5300 0.5288 0.5269
Using the standard calibration equation obtained from vitamin A standard that is
y = 8.4937x + 0.0813 where,
y – Concentration and x- absolute absorbance
Absorbance corrected = Absorbance of sample – Absorbance of the blank
Absorbance of the blank = 0.0000
Sample ID 104/2014
Average absorbance = (0.8105 +0.8123+0.8110 )
3 = 0.8113
y = (8.4937x0.8113) + 0.0813
y = 6.9722
Retinol concentration = (6.9722 𝑋 50)
27 .0081 = 12.9077g/g
Sample ID 105/2014
Average absorbance = (0.4498 +0.4494 +0.4493 )
3 = 0.4495
y = (8.4937x0.4495) + 0.0813
y = 3.8992
Retinol concentration = (3.8992 𝑋 50 )
27 .0084 = 7.2185g/g
Sample ID 108/2014
Average absorbance = (0.5300 +0.5288+0.5269)
3 = 0.5286
y = (8.4937x0.5286) + 0.0813
y = 4.5708
Retinol concentration = (4.5708 𝑋 50)
27 .0081 = 8.4619g/g
29
EXP 5: DETERMINATION OF β-CAROTENE
PIGMENT EXTRACTION OF β-CAROTENE ANALYSIS
This was carried out according to the method of the association of official chemist (AOAC,
1980). Into a conical flask containing 95% ethanol (50ml), macerated sample (10g) was
placed and maintained at a temperature of 70-800C in a water bath for 20 minutes with
periodic shaking. The supernatant was decanted, allowed to cool and its volume was
measured by means of a measuring cylinder and recorded as initial volume. The ethanol
concentration of the mixture was brought to 85 % by adding 15ml of distilled water and it
was further cooled in a container of ice water for about 5minutes. The mixture was
transferred into a separating funnel and 25ml of petroleum ether was added and the cooled
ethanol was poured over it. The funnel was swirled gently to obtain a homogeneous mixture
and it was later allowed to stand until 2 separate layers were obtained. The bottom layer was
run off into a beaker while the top layer was collected into a 250ml conical flask. The bottom
layer was transferred into the funnel and re-extracted with 10ml pet-ether for 5 times until the
extract became fairly yellow. The entire petroleum ether was collected into a 250ml conical
flask and transferred into a separating funnel for re-extraction with 50ml of 80% ethanol. The
final extract was measured and poured into sample bottles for further analysis.
MEASUREMENT OF ABSORBANCE
The absorbance of the extracts was measured using a spectrophotometer (model22UV/VIS)
at a wave length of 436 nm. A cuvette containing petroleum ether (blank) was used to
calibrate the spectrophotometer to zero point. Samples of each extract were placed in
cuvettes and readings were taken when the figure in display window became steady. The
operation was repeated 5 times for each sample and average readings were recorded. The
concentration of β-carotene was calculated using Bear- Lamberts law which states that the
absorbance (A) is proportional to the concentration (C) of the pigment as represented by the
equation:
A ∞L (if concentration (C) is constant)
A= ECL; C = 𝐴
𝐸𝐿
Where: C= concentration of carotene
A= absorbance
E= extinction coefficient
L= thickness of cuvettes (path length) = 1cm
30
E of β-carotene = 1.25×104µg/L
Sample ID: TB Sample
Table Showing Absorbance of the Sample
Replicate Absorbance
1 0.0771 0.0795
2 0.0668 0.0642
Average Absorbance = (0.0771+0.0795)
2 = 0.0783
Concentration C = 𝐴
𝐸𝐿
Concentration C = 0 .0783
12500 𝑋 1
= 6.26 x 10-6
31
PROXIMATE ANALYSIS OF FLOUR SAMPLE
Sample ID 178/2014
MOISTURE CONTENT DETERMINATION
Replicate 1 2 3
Weight of dry petri dish 85.8412 95.0268 87.1906
Weight of the sample 5.0013 5.0091 5.0007
Weight of the dry sample + petri dish 90.4325 99.6185 91.8278
Weight of the dry sample 4.5913 4.5917 4.6372
Moisture percentage 8.20 8.33 7.27
DETERMINATION OF ASH CONTENT
Replicate 1 2
Weight of dry crucible 61.9672 67.0590
Weight of the sample 5.0035 5.0016
Weight of the dry sample + crucible 62.0391 67.1304
Weight of the ash 0.0719 0.0714
% ash content 1.44 1.43
Average ash percentage 1.435
FAT CONTENT DETERMINATION
Replicate 1 2
Weight of dry aluminium cup 39.2008 38.7858
Weight of the sample 3.0028 3.0085
Weight of the oil + aluminium cup 39.3540 38.9309
Weight of the oil 0.1532 0.1451
% oil 5.10 4.82
Average percentage oil 4.96
32
3.2. TOUR TO OTHER PRODUCTION DEPARTMENTS IN THE INSTITUTE
A TOUR TO THE DAIRY PROCESSING PLANT
The products produced include; fresh milk, butter, low fat yoghurt, gee and ice cream. The
production process starts with receiving and testing milk. Testing is usually done by boiling,
use of alcohol and use of lactometer. By boiling, contaminated milk clots and when alcohol
is used, it ferments. This is followed by passing the milk in the de-aerator which removes air
then filtering and cooling the milk to a temperature of 4 0C.
The cooling system is used for cooling water to 4 0C and the compressor is used for cooling
water. These are connected to pumps that cool the product in the cycle using water. Milk
cooling is necessary to preserve milk for a long period of time.
Pasteurizer: the milk passes the balance tank to the first chamber at 40-500C. The second
chamber is at 65-700C. The pasteurizer is used to homogenize the milk. It is then passed the
secondary plate heat exchanger which cools it from 750C to 40C and then sent to the
balance/pressure tank.
Packing machine is sterilized using ultra violet (U.V) light. It packs 1 and 1
2 liter packs at an
expiry date of 5 days. The packed milk is taken to the cooling room or chiller at a
temperature of 40C.
For the case of ice cream milk is put in the tank which is double jacket. Water is filled in the
jacket and milk is put at a temperature of 500C. Ingredients and sugar are added at this
temperature. The temperature is then raised to 900C. Useful bacteria are also added at this
stage. Flavors are added in the order strawberry followed by vanilla and lastly chocolate then
food color. The product is then placed in deep freezers or in the cold room for chilling
allowing it to cool to very low temperatures. They are then taken to the incubator where U.V
light is passed for sterilizing. Yoghurt is not heated to high temperatures because it has
important bacteria which help in the fermentation process
Cleaning process
Hot water at a temperature of 800C is mixed with 2% sodium hydroxide. The water is heated
by steam and the size of the tank is 500,000mL. Cleaning is done before and after
production.
33
A TOUR TO THE FOOD PROCESSING PLANT
There are two sections involved that is training section and commercial section. Training
section involves students, entrepreneurs, product development. The products processed are
beef sausages, pork, chicken and vegetable sausages (which are still under research and
development). The challenge with vegetable sausages is that the water content is high so they
have to be first heated or dried. Salt is added to the sausages to enhance taste. Nitrate salts
added as sodium nitrate serve three uses; it improves taste, used to enhance color (reduces the
red color), finally used for preservation that is it prevents bacterial attack. In the production
rooms there are low temperatures to reduce on the susceptibility of microbial attack.
In the production process there are various unit operations such as size reduction of meat and
fat to form mist meat, meat mixing by the meat mixing machine. This is followed by bowl
cutter where ingredients are added. Animal fat is used mostly compared to vegetable fat
because animal fat has a high binding capacity.
Cleaning; this is done using liquid soap, jik, hot water. Perfumed detergents are not used.
Storage facilities; the processed product are kept at -180C and for raw materials they are
stored at 0 to -20C. The deep frozen product has a shelf life of a year.
The bowl cutter temperatures are controlled at 130C by adding some ice. This ice also
dissolves the ingredients added that is phosphate, common salt, garlic powder and ginger
34
A VISIT TO THE JUICE PROCESSING PLANT
The raw materials processed include fruits and vegetables. Fruits are not attacked by bacteria
because they have a low P.H while vegetables have a high P.H. The section deals with
processing of wine, vegetables, juice both local and herbal. The following activities take
place;
a. Reception; the fruits are received and quality confirmatory tests are carried out for
example determining the sugar content by determining brix in juice, determination of
P.H (depends on the degree of ripeness), determination of titratable acidity citric acid
or malic acid, physical tests such as color, defects, hygiene of the truck delivering
them.
b. Weighing and sorting; this is intended to reduce bad ones from bad ones
c. Washing; this removes the physical dirt, and then rinsed with warm water and
disinfected with sodium metabisulphite 0.05%.
d. This is followed by peeling, slicing when the fruits are few.
e. Then the product is taken to the processing room where pulping occurs. This involves
the following machines.
1) Crusher; this acts as a big blender which should be first cleaned before use.
2) Passion pulper; this crushes passion, water melon and tomatoes
3) Pineapple and mango pulper and the holding tank for temporary storage and then to
the mixing tank
f. The product is then channeled to the blending tanks which are two each of 1000ml.
water, sugar, thickeners’ i.e. CMC, and stabilizers are added.
g. This is then directed to the de-aerator which removes air because air facilitates
oxidation which turns the juice brown. It is at a pressure of -0.02 to -0.06. This is then
directed to the balance tank.
h. This is then passed in the sterilizer (between 150 and 1200C) or pasteurizer below
900C. This is connected to the heat exchanger which acts in the counter current
direction.
i. This is then channeled to the homogenizer to prevent phase separation.
Packaging; this involves the buffer tank which removes juice at 400C which is connected
to the balance tank. This packs 1,1
2 and
1
4 liters. It has conveyer belts and sensors which
aid in packaging.
CIP (cleaning in place)
It uses the acid to remove acidic particles and after a base is passed to neutralize the
acidic P.H
35
3.3. ANALYSIS OF FRUIT JUICES
EXP 6: DETERMINATION OF VITAMIN C
Vitamin C (ascorbic acid) is an antioxidant that is essential for human nutrition. Vitamin C
deficiency can cause a disease called scurvy, which is characterized by abnormalities in the
bones and teeth, many fruits and vegetables contain vitamin C but cooking destroys the
vitamin, so raw citrus fruits and juices are the main source of ascorbic acid for most people.
One way to determine the amount of vitamin C in food is to use a redox titration. The redox
reaction is better than an acid base titration since there are additional acids in juice, but few
of them interfere with the oxidation of ascorbic acid by iodine.
Iodine is relatively insoluble but this can be improved by complexing the iodine with iodide
to form tri-iodide.
I2 (aq) + I- (aq) ⇋ I3-(aq)
Tri iodide oxidizes vitamin C to form hydro ascorbic acid.
C6H8O6 + I3-(aq) + H2O (l) ⇋ C6H6O6 +I2 (aq) +2H+ (aq)
As long as vitamin C is present in the solution the tri-iodide is converted to iodide ion very
quickly. However, when all the vitamin C is oxidized iodine and tri-iodide will all be present
which reacts with starch to form a blue -black complex. The blue –black is end point of the
titration. The titration procedure is appropriated for testing the amount of Vitamin C in
vitamin C tablets, juices, and fresh, frozen, or packaged fruits and vegetables. The titration
can be performed using just iodine solution and not iodate, but the iodate solution is more
stable and gives a more accurate result.
Purpose
The goal of this laboratory exercise is to determine the amount of vitamin C in samples such
as fruit juice.
PROCEDURE
Preparing solutions
1% starch indicator solution
Soluble starch (0.5g) was added to distilled water and then heated to near boiling. The
solution was mixed well and allowed to cool before use.
36
Iodine solution
Potassium iodide (5.0030g) and potassium iodate (0.2681g) were dissolved in distilled water
(200ml) and 3M sulphuric acid solution (30ml) was then added. This solution was poured
into a 500ml graduated cylinder and filled to the mark with distilled water. The solution was
mixed properly and then transferred to a 600ml beaker. The beaker was labeled as iodine
solution.
Vitamin C standard solution
Vitamin C (0.2509g) was dissolved in distilled water (100ml) in a 250ml volumetric flask
and then diluted to the mark. The flask was labeled vitamin C standard solution.
Standardizing solutions
Vitamin C standard solution (25.00ml) was added to Erlenmeyer flask and 1% starch solution
(10 drops) were then added. The burette was rinsed with small volume of the iodine solution
and then filled. The initial volume was recorded. The solution was titrated until the end point
was reached (when the first sign of the blue color that persists after 20 seconds of swirling
the solution).The final volume of iodine solution was recorded. The volume that was required
is the final volume minus the starting volume. The titration was repeated once. The juice
samples were exactly titrated the same way as the standard. The initial and final volume of
iodine solution required to produce the color change at the end point were recorded in the
table as shown below.
RESULTS AND TREATMENT
Mass of Ascorbic Acid = 0.2509g
Potassium iodide = 5.0030g
Potassium Iodate = 0.2681g
Starch = 1.0003g
Table of Results
Vitamin C standard
Volume of solution taken = 25ml
Replicate 1 Replicate 2
Final burette reading (ml) 27.80 30.30
Initial burette reading (ml) 9.20 11.80
Volume of iodine solution used (ml) 18.60 18.50
37
Sample ID: 064/2014
Volume of solution taken = 25ml
Replicate 1 Replicate 2 Replicate 3
Final burette reading (ml) 8.50 9.60 10.60
Initial burette reading (ml) 7.40 8.50 9.60
Volume of iodine solution used (ml) 1.10 1.10 1.00
Sample ID: 065/2014
Volume of solution taken = 50ml
Replicate 1 Replicate 2 Replicate 3
Final burette reading (ml) 9.50 9.80 10.20
Initial burette reading (ml) 9.00 9.50 9.80
Volume of iodine solution used (ml) 0.50 0.30 0.40
Sample ID: 173/2014
Volume of solution taken = 50ml
Replicate 1 Replicate 2 Replicate 3
Final burette reading (ml) 11.80 12.10 12.50
Initial burette reading (ml) 11.50 11.80 12.10
Volume of iodine solution used (ml) 0.30 0.30 0.40
Sample ID: 174/2014
Volume of solution taken = 50ml
Replicate 1 Replicate 2 Replicate 3
Final burette reading (ml) 13.30 13.90 14.50
Initial burette reading (ml) 12.50 13.30 13.90
Volume of iodine solution used (ml) 0.80 0.60 0.60
38
Sample ID: Orange
Volume of solution taken = 50ml
Replicate 1 Replicate 2 Replicate 3
Final burette reading (ml) 17.00 19.40 21.80
Initial burette reading (ml) 14.50 17.00 19.40
Volume of iodine solution used (ml) 2.50 2.40 2.40
TREATMENT OF RESULTS
Using the relation,
ml of Iodine solution in the standard
0.2509g of vitamin C =
ml of Iodine solution required for the sample
x g of vitamin C in the sample
Average volume of vitamin C standard = 18.60+18.50
2 = 18.55ml
Sample ID: 064/2014
Average volume of vitamin C in sample = 1.10+1.10+1.00
3 = 1.067ml
18.55ml
0.2509g of vitamin C =
1.067
x g of vitamin C in the sample
X =(1.067 x 0.2509
18.55 ) g = 0.0144g
Concentration of vitamin C = 0.0144g
0.025L
= 0.577g/L
Similarly the concentration of vitamin C in the samples were calculated and recorded in the
table below.
Sample ID Vitamin C concentration (g/L)
065/2014 0.1082
173/2014 0.09
174/2014 0.1803
Orange 0.658
39
EXP 7: DETERMINATION OF TOTAL TITRATABLE ACID IN FRUIT JUICES
APPARATUS
Analytical balance
Burette
Conical flasks
Pipette
250ml volumetric flask
Filter paper whattman No.40
PROCEDURE
Juice samples (30ml) were measured, dissolved in distilled water in a 250ml volumetric flask
and topped up to the mark. The solution was filtered and the filtrate (100ml) titrated with 0.1
N sodium hydroxide using phenolphthalein as indicator. When the alkali is added a brownish
color might develop which may mask the end point. Add more distilled water and use more
indicator than is normally required. The end point should have light pink color.
RESULTS AND CALCULATION
Sample ID: 064/2014
Volume of solution taken = 100ml
Replicate 1 Replicate 2
Final burette reading (ml) 15.80 10.10
Initial burette reading (ml) 14.50 8.70
Volume of NaOH solution used (ml) 1.30 1.40
Sample ID: 065/2014
Volume of solution taken = 100ml
Replicate 1 Replicate 2
Final burette reading (ml) 18.80 21.80
Initial burette reading (ml) 15.80 18.80
Volume of NaOH solution used (ml) 3.00 3.00
40
Sample ID: 173/2014
Volume of solution taken = 100ml
Replicate 1 Replicate 2
Final burette reading (ml) 15.50 16.40
Initial burette reading (ml) 14.20 15.40
Volume of NaOH solution used (ml) 1.30 1.00
Sample ID: 174/2014
Volume of solution taken = 50ml
Replicate 1 Replicate 2
Final burette reading (ml) 13.90 14.20
Initial burette reading (ml) 13.50 13.90
Volume of NaOH solution used (ml) 0.40 0.30
Sample ID: Orange
Volume of solution taken = 50ml
Replicate 1 Replicate 2
Final burette reading (ml) 22.80 15.00
Initial burette reading (ml) 16.40 8.90
Volume of NaOH solution used (ml) 6.40 6.10
Acidity as anhydrous citric acid =𝑡𝑖𝑡𝑟𝑒 𝑣𝑎𝑙𝑢𝑒 ×𝑛𝑜𝑟𝑚𝑎𝑙𝑖𝑡𝑦 𝑜𝑓 𝑎𝑙𝑘𝑎𝑙𝑖 ×64×𝑣𝑜𝑙𝑢𝑚𝑒 𝑚𝑎𝑑𝑒 𝑢𝑝×100
𝑚𝑙 𝑜𝑓 𝑓𝑖𝑙𝑡𝑟𝑎𝑡𝑒×𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒×1000
41
EXP 8: PROTEIN CONTENT DETERMINATION IN FRUIT JUICES
Principle
The sample is prepared which includes, grinding for solid samples, it is digested in
concentrated sulphuric acid and 1% copper sulphate (Kjeldahl) tab as catalyst, then
distilled in 40% sodium hydroxide, the ammonium liberated is absorbed in (4%) boric
acid having methyl red / bromocresol green as indicator and later titrated with 0.1N
hydrochloric acid or sulphuric acid.
The boiling temperature is elevated by addition of potassium sulphate. The elevated boiling
temperature is necessary to break the peptide bonds and convert amino groups in protein to
ammonium ions. A copper catalyst is added to enhance reaction rate. After digestion the
digest mix is diluted with water to avoid mixing concentrated alkali with concentrated acid
and to prevent the digest from solidifying. Ammonia is the liberated by alkaline distillation
and quantified by titration with standardized acid.
Reagents and materials
Concentrated sulphuric acid AR grade
Copper sulphate (CuSO4) AR grade
Sodium pellets, AR grade
Boric acid
Methyl orange indicator
Bromocresol green indicator
Distilled water
Lysine chloride – 99.9 % C11H12N2O2 or C6H15ClN2O2
Catalyst use copper tablets, kjel tabs
PROCEDURE
Digestion
The sample was added in the digestion tube followed by 1 tab of Kjeldahl catalyst,
and then concentrated H2SO4 (12ml).
Note: A similar digestion tube is set as blank i.e. without sample, and should go through
same treatment).
The content was shaken gently to “wet” the sample. The exhaust was positioned and
aspirator turned on. The digestion unit was turned on and temperature set at 410°C.
The digestion was allowed to run at this temperature for 1hour until the digestion tube
content became colorless, light blue or green. After digestion power was switched off
and unit allowed to cool down to 40 – 30°C.
42
Distillation
Cooled digest was diluted with 50ml distilled water, and the tube fixed tightly at its
position in the distillation unit. 25ml of receiver solution (H3BO3) and 5 drops of
indicator (Methyl red / Bromocresol green) were added in a conical flask. The
conical flask was fixed at its position in the distillation unit ensuring that the tip of
plastic tube enters below the surface of the receiver solution.
Using the handle for alkali dispensing on the right hand of the distillation unit, 50ml
of 40% NaOH solution were added to the diluted digest to avoid over reaction.
Note: Need to mark off the 50ml level above the level of the diluted cooled digest on the
digestion tube.
The distillation apparatus was switched on. When boiling starts, timer was set to 4min
and steam immediately opened using the close-open button. When the bell of the
timer rings, then distillation is ending, when the bell stops ringing, power was
immediately switched off and steam closed. The set up was left for about 3minutes to
allow all the condensate to collect into the receiver solution. The plastic tubing was
rinsed with little distilled water into the receiver solution as the flask is being
removed.
Titration
The H3BO3 – HN3 solution was titrated in receiver flask with Standard 0.1N HCl (or 1M
HCl) or H2SO4 solution. End point was from light blue to pale yellow.
TABLE OF RESULTS
Sample ID 064 065 066 173 174
Weight of sample taken (g) 1.3395 1.6588 1.8092 1.7095 1.2247
Volume of HCl (ml) 0.45 0.40 1.45 0.40 0.30
%age nitrogen 0.0366 0.0253 0.1045 0.0246 0.0229
% age protein 0.2288 0.1584 0.6531 0.1537 0.1430
Blank titre =0.10ml
Concentration of the acid = 0.1N
43
% Kjeldah nitrogen =(𝑉𝑠−𝑉𝑏 )×𝑁×14.01
𝑊 ×10
Vs. = ml of standardized acid used to titrate the sample
Vb =ml of standardized acid used to titrate the blank
N = normality of standard HCl
14.01= atomic weight of nitrogen
W= weighted the sample or standard
10 = factor to convert nitrogen to protein mg/g percent
The % age crude protein is calculated according to the formula below.
% age crude protein = % Kjeldah nitrogen x F
F – Factor used to convert nitrogen to proteins. Factors are;
6.25 – feeds, meat, and other samples not specified
5.70 – wheat
Sample calculation
Sample ID: 064/2014
% Kjeldah nitrogen =(𝑉𝑠−𝑉𝑏 )×𝑁×14.01
𝑊 ×10
= (0.45−0.10)×0.1×14.01
1.3395×10
= 0.0366%
% age crude protein = % Kjeldah nitrogen x F
= 0.0366 x 6.25
= 0.2288%
44
3.4 SOAP ANALYSIS
EXP 9: DETERMINATION OF pH VALUE OF SOAP SAMPLE
1.0ml of the test sample was dissolved in 100mls of distilled water and the pH measured at
room temperature, using a pH meter equipped with a glass electrode capable of measuring
pH values with an accuracy of 0.1
RESULTS
Sample ID A B
Replicate 1 2 1 2
pH of soap 6.24 6.23 2.94 2.91
Temperature (0C) 25.8 25.8 25.5 25.5
Average PH 6.236 2.925
EXP 10: DETERMINATION OF INORGANIC SALTS
PROCEDURE
The sample (5.0060g) was weighed into a crucible and placed on a heating mantle to
evaporate volatile matter. After evaporation, the crucibles are placed in a muffle furnace set
at 4500c for 6 hours. The dish and its contents were cooled and a few drops of concentrated
sulphuric acid added. The mixture was then heated again to dryness, cooled and weighed.
The process of heating, cooling and weighing was repeated until constant mass was obtained.
The experiment was then repeated with another replicate of 5.0119g and another sample.
RESULTS AND TREATMENT
Sample A
Replicate 1 Replicate 2
Weight of crucible + sample
before heating (g)
127.8244 121.2784
Weight of crucible (g) 122.8184 116.2668
Weight of sample (g) 5.0060 5.0119
Weight of Ash + crucible (g) 123.0380 116.4861
45
Sample B
Replicate 1 Replicate 2
Weight of crucible + sample
before heating (g)
130.1164 130.5936
Weight of crucible (g) 125.1072 125.5809
Weight of sample (g) 5.0092 5.0127
Weight of Ash + crucible (g) 125.3630 125.8349
The inorganic salts content is given, as a percentage by mass, by the formula
(𝑀1 − 𝑀3)
(𝑀1 − 𝑀0) × 100
Where MO is the mass in grams of the dish
M1 is the mass in grams of the dish and the sample before heating
M3 is the mass in grams of the dish and the residue
Sample A
Replicate 1
% inorganic solids = (127 .8244−123.0380
127 .8244−122.8184 ) 𝑥100%
= 95.61%
Replicate 2
% inorganic solids = (121 .2784−116.4861
121 .2784−116.2668 ) 𝑥100%
= 95.62%
Calculation of mean percentage
Mean =∑𝒙
𝒏 =
(𝟗𝟓.𝟔𝟏+𝟗𝟓.𝟔𝟐)
𝟐= 𝟗𝟓.𝟔𝟏𝟓%
46
Calculation of standard deviation
Percentage X Deviation (X— X ) Square deviation (X— X )2
95.61 -0.005 0.000025
95.62 0.005 0.000025
∑ (X— X )2 = 0.00005
Standard deviation = √(∑(X— X )2)
𝒏−𝟏
=√(0.00005)
𝟐= 𝟎. 𝟎𝟎𝟓%
Calculation of Relative standard deviation (RSD)
RSD = 𝑺𝒕𝒂𝒏𝒅𝒂𝒓𝒅 𝒅𝒆𝒗𝒊𝒂𝒕𝒊𝒐𝒏
𝒎𝒆𝒂𝒏 =
(0.005)
94 .615 x 100%
= 0.0053%
Sample B
Replicate 1
% inorganic solids = (130 .1164−125.3630
130 .1164−125.1072 ) 𝑥100%
= 94.89%
Replicate 2
% inorganic solids = (130 .5936 −125 .8349
130 .5936 −125 .5809 ) 𝑥100%
= 94.93%
47
USING THE SAME PROCEDURE
Mean = 94.91
Standard deviation = 0.02%
RSD = 0. 0211%
3.5. WATER ANALYSIS
Water was basically analyzed using the multi-probe Maji meter which analyses pH,
Turbidity, electrolytic conductivity (EC), dissolved oxygen (DO), total dissolved solids
(TDS), Altitude, latitude and longitude.
48
CHAPTER FOUR: RECOMMENDATIONS, CONCLUSION AND
REFERENCES
4.1. LIST OF SKILLS ACQUIRED
I acquired new knowledge and practical experiences for example in handling different
lab equipment and carrying out different tests such as protein analysis, fat
determination moisture determination, ashing, among others which improved my
confidence in problem solving.
I obtained skills in relating with employees and different class of people as the
organization had a wide category of people.
I also obtained time management skills because we were supposed to reach in time
during the course of training.
I was able to apply the principles and techniques theoretically learnt in class into real-
life problem solving situations carried out in the laboratory.
I acquired practical skills in operation and safety of laboratory apparatus and
machines involved in activities of an operational environment, and perfecting in
various operating techniques, for example operating an Atomic Absorption
Spectrophotometer.
I managed to perform individual assignments on how to conduct experiments and
operating equipment when performing laboratory activities or tests.
4.2. RECOMMENDATIONS
A. To The Organization (UIRI)
More glass ware or apparatus should be provided for example the test tubes and
burettes for efficiency at work
Adopting a practice of weekly rotations in other related sections other than just a one
day tour. This will ensure an appropriate training for example in production systems
where unit operations are very common.
Repair of the un-functional equipment and replacement of broken glass ware which
may lead to accidents of glass cuts and toxic reagents harming the personnel handling
the experiment.
Implementation of systems and processes that may improve on the trainee’s skills, for
example planning in advance the work to be carried out in a week. This ensures a
better understanding of the experiments to be worked on since there is time to
research before carrying out the experiments, and delegation of work this will ensure
responsibility and time management of the trainees.
49
B. To The University
Providing marks allocation forms to the organizational supervisor such that they can
also allocate marks because they understand students better since they usually work
with them daily
Increasing on the number of pages of the log book because the space where to write
the daily activities was not enough.
Introduction of course unit(s) about research project such that students are acquainted
with enough information about the research project.
4.2. CONCLUSION A lot of experience has been acquired in this training period most especially food, water, and
soap analyzes which are very important in my career. Also I got a chance to see the relevant
unit operations which exist in other sections of the organization such as dairy and fruit
production section. It also improved on my interpersonal skills on how to relate with fellow
workmates, proper record keeping, as well as time management.
50
4.3. REFERENCES
Pearson D, Melon H. K, and Ronald S, (1976). Chemical Analysis of Food. (8th edition).
Churchill Livingstone. (Pages 60-63).
Kirk, R.S. and Sawyer, R. (1991): Pearson's Composition and Analysis of Foods, Longman
Scientific and Technical. 9th Edition, England.
Ranganna, S. (1986): Handbook of Analysis and Quality Control for Fruit and Vegetable
Products, 2nd edition, Tata McGraw Hill Publishing Co. Ltd., New Delhi.
G.H.Jeffery, J.Bassett, Mendham, R.C.Denney, (1989) Vogel’s Text book of Quantitative
Chemical Analysis, 5th Edition, Pearson Edu.ltd.Singapore.
William T. Hall. (1916). Analytical Chemistry. “Quantitative Analysis”. (Volume 1).
Chapman and Hall. John Wiley and Sons, Inc. London. New York.
Lehninger. A. (1993). Principles of Biochemistry. (3rd edition). Worth publishers. New York.
(Pages 184-185).
Dyke S. F. (1960). The Carbohydrate. (Volume 5). Inter science Publishers. New York.
(Pages 120-125).
www.labpro.co.uk/pHmeters/technical2012 European Instrumentation on 22/July/2014 at
9:50am.
http://www.uiri.0rgwednesday,01/october/2014.09:07.
Britton G. (1995). Carotene. www.microsoftencarta/carotene.com. 27/June/2014 04:00pm
http://en.wikipedia.org 02/August/2014 03:00pm
http://www.biocompare.com/Lab-Equipment/7929 02/August/2014 03:05pm
http://sellwoodsoap.wordpress.com 12/August/2014 02:00pm
http://www.bris.ac.uk/nerclsmsf/techniques/gcms.html 12/August/2014 02:00pm
Association of Official Analytical Chemists International. (1995). Official Methods of
Analysis of AOAC International. (16th edition). Method 4.1.10 (942.015), AOAC
International. Maryland. United States of America.
Atomic Absorption Spectroscopy. “Analytical methods”. (1996). Perkin-Elmer Corporation.
51
APPENDIX
STANDARD MARK
Uganda Industrial Research Institute Logo
STANDARD OPERATING PROCEDURES (S.O.PS)
a) WORK INSTRUCTION FOR ANALYSIS OF RECEIVED SAMPLES
This S.O.P explains the procedure for analyzing samples after reception in the laboratory in
order to ensure systematic analysis, record keeping and good results. This is to ensure that
analysis for all samples is done in a traceable manner and that all received samples are
analyzed using appropriate methods
PROCEDURE
- Check in the sample reception book for any pending sample for analysis
- Pick the sample from the sample cabinet
- Use the suitable valid method according to the List of methods
- Prepare your personal work book for recording results.
- Run the experiment as per the method selected
- Record the observations and results as per work instruction UIRI/CHEM/SOP/05.
- Return used apparatus, equipment and reagents to their storage areas as per Lab ware
storage list.
- Clean your work bench
- Hand over your results for calculation and checking as per work instruction
UIRI/CHEM/SOP/06.
b) WORK INSTRUCTIONS FOR CLEANING LABORATORY EQUIPMENT.
Cleaning equipment requires a special level of safety awareness. Keep these things in mind.
Read and follow all instructions on the equipment you are handling.
Unplug equipment from power and water supply.
Read safety requirements for the equipment
52
The aim of this SOP is to keep all equipment clean and in safe working environment. This
improves performance of equipment
PROCEDURE
Unplug the equipment from power and water supply.
Wear protective gloves
Dust equipment with a dry towel.
Dust the equipment table.
Use a moist towel previously dipped in dilute liquid soap to clean the equipment
Wipe the equipment completely dry with a dry towel.
Record and sign in the equipment log book.
Obtaining 3M sulfuric Acid used in vitamin C determination
Molarity = % Assay x Density
RFM x 1000
= 96.5
100 x
1.84
98.08 x 1000
Molarity of the stock solution = 18.1036M
Using the relation,
Concentration of conc solution x volume = concentration of dilute solution x volume
C1V1 = C2V2
18.1036 x V1 = 3 x 50
V1 = 3 x 50
18.1036 = 8.29ml
Therefore 8.29ml of the stock solution was taken and diluted to the 50ml mark using distilled
water.
53
WASTE MANAGEMENT
Waste produced Management
Water Drained in septic tank
Ash Poured into bins and collected by waste removal
company
Alcoholic beverage solutions and
soft drinks
Collected, diluted and poured down the drain
Residual samples for example flour
grains
Removed from their packaging, poured into bins and
collected by a contracted waste removal company
Solutions of acids used (nitric,
hydrochloric, sulphuric, caustics among others)
Diluted adequately with water and poured in the
septic tank
Broken glass Collected in one container later taken by the waste removal company
Empty reagent containers (glass and
plastic)
Collected by waste removal company
Top Related