safely hydrogenate refined lipids to achieve specific product qualities
accurately winterize hydrogenated lipids to meet required standards
correctly plasticize winterized lipids to match product specifications
Mastering these skills will help you produce high-quality edible fats and oils that meet industry demands and customer expectations.
Processing edible lipids such as fats and oils is central to food technology, enabling the transformation of raw oils into forms suitable for diverse food applications. In Kenya’s food industry, modifying fats and oils improves product stability, texture, shelf life, and nutritional value, which is crucial for manufacturers supplying bakeries, confectioneries, and snack producers. This chapter explores the principal methods used to modify edible lipids, including hydrogenation, winterisation and fractionation, interesterification, and plasticizing actions, all of which contribute to tailoring lipid properties to meet specific food formulation requirements.
3.1 Fats and Oils Modification
Modification of edible fats and oils involves altering their physical and chemical characteristics to enhance functionality in food products. These processes adjust melting points, oxidative stability, and texture, ensuring that fats meet the demands of different culinary and industrial uses. Kenyan food producers use these techniques to optimize local vegetable oils such as sunflower, cottonseed, and palm oil for products ranging from margarine to bakery spreads.
3.1.1 Hydrogenation
Hydrogenation is a chemical process that adds hydrogen atoms to unsaturated fatty acids in oils, converting them into more saturated forms. This modification improves oil stability, raises melting points, and extends shelf life, which is vital in tropical climates where oxidation rates are high.
Purpose of Hydrogenation
The primary purpose of hydrogenation is to increase the oxidative stability of oils, preventing rancidity and off-flavours during storage and cooking. It also modifies melting points to produce semi-solid fats suitable for margarine, shortening, and confectionery fats. In Kenya, hydrogenation enables the use of locally sourced oils in products requiring solid fats, such as pastries and fried snacks.
Process of Hydrogenation
Hydrogenation involves several steps conducted under controlled conditions:
Preparation of oil: The oil is filtered and purified to remove impurities that could interfere with the reaction.
Introduction of hydrogen: Hydrogen gas is bubbled through the oil in the presence of a catalyst, commonly nickel.
Reaction control: Temperature (120–210°C) and pressure (2–10 atm) are maintained to optimize hydrogen uptake.
Monitoring: The degree of saturation is monitored by measuring iodine value or hardness.
Termination: When the desired saturation level is reached, hydrogen flow is stopped.
Post-processing: The oil is filtered to remove the catalyst and deodorized to eliminate odours.
Types of Hydrogenation
There are three common types of hydrogenation used in edible oil processing:
Partial hydrogenation: Converts some double bonds to single bonds, producing semi-solid fats but may generate trans fats.
Full hydrogenation: Saturates all double bonds, resulting in a fully solid fat with no trans fats.
Selective hydrogenation: Targets specific unsaturated bonds to control melting characteristics and reduce trans fat formation.
Impact on Nutritional and Functional Properties
Hydrogenation affects both nutrition and functionality:
Nutritional impact: Partial hydrogenation may produce trans fatty acids linked to cardiovascular risks; therefore, full hydrogenation or alternative methods are preferred in health-conscious markets.
Functional impact: Increases melting point and plasticity, improving texture and spreadability in margarine and bakery fats.
Oxidative stability: Saturated fats are less prone to oxidation, enhancing shelf life in hot climates like Kenya’s.
Application versatility: Enables production of fats tailored for frying, baking, or confectionery.
3.1.2 Winterisation and Fractionation
Winterisation and fractionation are physical processes used to separate oils into fractions with different melting points and compositions. These techniques improve clarity, texture, and usability in various food applications.
Principle and Purpose of Winterisation
Winterisation removes high-melting point triglycerides that crystallize at low temperatures, preventing cloudiness in oils used for salad dressings and cooking oils. This process is essential for maintaining product appeal and consumer acceptance in Kenya’s retail edible oil market.
Procedure of Winterisation
The winterisation process involves:
Cooling: The oil is slowly cooled to 0–10°C to encourage crystallization of waxes and saturated fats.
Holding: The oil is held at low temperature to allow complete crystal formation.
Filtration: Crystals are removed by filtration or centrifugation.
Clarification: The resulting oil is clear and stable at refrigeration temperatures.
Packaging: The clarified oil is packaged for sale or further processing.
Fractionation: Definition and Purpose
Fractionation separates a fat or oil into two or more fractions with distinct melting points by controlled cooling and crystallization. It produces fractions like stearin (high melting) and olein (low melting), enabling manufacturers to tailor fats for specific food products such as spreads, frying oils, and chocolate.
Fractionation Methods
Common fractionation methods include:
Dry fractionation: Controlled cooling and physical separation of crystals without solvents; favoured for edible oils due to safety.
Solvent fractionation: Uses solvents to dissolve oil and separate fractions; less common due to solvent residues.
Press fractionation: Applies pressure to separate solid and liquid fractions; limited use in food fats.
3.1.3 Interesterification
Interesterification rearranges fatty acids on the glycerol backbone of triglycerides without changing their degree of saturation. This process modifies melting behaviour and functional properties without producing trans fats.
Purpose of Interesterification
The goal is to produce fats with specific melting profiles and improved plasticity for use in margarine, bakery fats, and confectionery. In Kenya, interesterified fats are increasingly used to replace partially hydrogenated oils in response to health regulations.
Types of Interesterification
Two main types exist:
Chemical interesterification: Uses chemical catalysts like sodium methoxide to randomize fatty acids.
Enzymatic interesterification: Employs lipase enzymes for more specific and controlled rearrangement, resulting in fewer by-products.
Process Steps in Chemical Interesterification
Preparation: Oils and fats are purified and dried to remove moisture.
Catalyst addition: Sodium methoxide is added to initiate the reaction.
Reaction: The mixture is maintained at 50–90°C for 1–2 hours to allow fatty acid rearrangement.
Neutralization: Catalyst is neutralized with acid.
Washing: The product is washed to remove residual catalyst and impurities.
Drying: The final interesterified fat is dried and deodorized.
Functional Effects on Edible Fats
Interesterification changes melting points and crystallization behaviour, enhancing spreadability and texture without trans fats. It also improves oxidative stability and allows blending of fats with diverse fatty acid profiles for customized food applications.
3.1.4 Plasticizing Actions
Plasticizing refers to modifying fats to achieve a semi-solid consistency that is malleable yet stable, essential for products like margarine and bakery shortenings.
Meaning and Significance of Plasticizing in Food Fats
Plasticizing alters the crystalline structure of fats to produce a spreadable texture that can trap air and provide desirable mouthfeel. This is critical in Kenyan bakery and confectionery industries where texture influences product quality and consumer preference.
Methods to Achieve Plasticizing Action
Plasticizing can be achieved by:
Blending fats with different melting profiles to create a stable plastic phase.
Hydrogenation to increase saturation and melting points.
Interesterification to rearrange fatty acids and modify crystallization.
Addition of emulsifiers to stabilize fat crystals and improve consistency.
Characteristics of Plasticized Fats
Plasticized fats exhibit:
Spreadability: Easy to spread at refrigeration temperatures.
Stability: Resistance to oil separation and graininess.
Aeration capacity: Ability to incorporate air for light textures.
Melting behaviour: Melts cleanly at body temperature for pleasant mouthfeel.
Applications of Plasticized Fats in Kenyan Food Industry
Plasticized fats are used extensively in margarine production, cake shortenings, and frostings. Local producers in Nairobi and Kisumu rely on these fats to meet consumer demands for quality baked goods with consistent texture and shelf life.
Practice Questions
Explain the chemical changes that occur during hydrogenation and their impact on the physical properties of edible oils. (10 marks)
Describe the winterisation process and its importance in maintaining oil quality for salad dressings. (8 marks)
Compare chemical and enzymatic interesterification in terms of process and product characteristics. (12 marks)
Discuss the role of plasticizing actions in the production of bakery shortenings and the factors influencing plasticity. (10 marks)
Chapter Summary
This chapter explored the various methods used to modify edible lipids to improve their functionality and applications in food products. Hydrogenation was examined as a chemical process that alters the degree of unsaturation in fats and oils, enhancing stability and shelf life. The chapter then discussed winterisation and fractionation techniques, which separate components based on melting points to produce clearer oils or distinct fat fractions. Interesterification was covered as a method that rearranges fatty acids within triglycerides, resulting in modified melting characteristics without producing trans fats. Finally, the plasticizing actions of fats and oils were explained, highlighting their role in determining texture and spreadability in food formulations. Together, these modification processes enable the tailoring of lipid properties to meet specific industrial and consumer needs.
Define hydrogenation and explain its purpose in edible oil processing. (3 marks)
Which of the following processes separates oils based on melting points?
a) Hydrogenation
b) Winterisation
c) Interesterification
d) Plasticizing actions (1 mark)
Describe the effect of interesterification on the physical properties of fats. (3 marks)
What is the primary goal of winterisation in vegetable oil processing? (2 marks)
List two advantages of hydrogenating oils in the Kenyan food industry. (2 marks)
Explain how plasticizing actions influence the texture of margarine products. (3 marks)
During the fractionation process, what determines the separation of oil fractions? (2 marks)
Identify one health consideration linked to partial hydrogenation of fats. (2 marks)
Match the process to its description:
a) Hydrogenation
b) Winterisation
c) Interesterification
d) Plasticizing actions
i) Rearrangement of fatty acids on the glycerol backbone
ii) Removal of high melting point triglycerides to avoid cloudiness
iii) Addition of hydrogen to unsaturated bonds
iv) Enhancing spreadability and plasticity of fats
(4 marks)
Explain why interesterification is preferred over hydrogenation in some modern edible oil applications. (3 marks)
Show Answers
Hydrogenation is the chemical addition of hydrogen to unsaturated fatty acids in oils to reduce double bonds, thereby increasing saturation. Its purpose is to improve stability, shelf life, and melting point for food applications.
b) Winterisation
Interesterification rearranges fatty acids on the glycerol backbone without altering saturation, resulting in modified melting behavior and improved functional properties such as plasticity and spreadability.
To remove high melting point triglycerides that cause cloudiness when oils are refrigerated, ensuring clarity and stability in the final product.
Advantages include improved oxidative stability of oils used in frying and enhanced texture in bakery products, which improves product quality and shelf life.
Plasticizing actions reduce intermolecular forces among fat crystals, creating a softer, more malleable texture ideal for spreads like margarine.
The melting point differences of triglycerides determine separation; higher melting fractions crystallize and separate from lower melting liquid fractions.
Partial hydrogenation can produce trans fatty acids, which have been linked to increased risk of cardiovascular diseases.
a-iii) Addition of hydrogen to unsaturated bonds
b-ii) Removal of high melting point triglycerides to avoid cloudiness
c-i) Rearrangement of fatty acids on the glycerol backbone
d-iv) Enhancing spreadability and plasticity of fats
Interesterification avoids trans fat formation and allows tailored fat functionalities without increasing saturation, making it healthier and more versatile for modern food products.
B. Oral Assessment
Discuss how the choice between hydrogenation and interesterification impacts the nutritional profile and functionality of edible oils used in Kenyan bakery products.
Explain the significance of winterisation and fractionation in ensuring quality standards for cooking oils distributed in Nairobi supermarkets.
Answer Guide
Question 1 key points:
Hydrogenation increases saturation and can produce trans fats, which negatively affect health.
Interesterification rearranges fatty acids without creating trans fats, improving texture and melting properties.
Choice affects shelf life, product stability, and consumer health perceptions in bakery items.
Kenyan bakeries must balance functionality for pastries with health-conscious consumer demands.
Question 2 key points:
Winterisation removes waxes and high melting triglycerides that cause cloudiness, improving oil clarity.
Fractionation separates oil into fractions with different melting points, enhancing suitability for various culinary uses.
These processes help meet regulatory quality requirements and consumer expectations for purity and appearance.
Ensures oils remain stable and visually appealing under Nairobi’s varying climatic conditions.
C. Case Study
At Bidco Africa’s edible oils processing plant in Thika, the production team is considering modifying palm oil to improve its functionality for use in margarine and bakery fats.
Tasks:
a) Explain how interesterification could be applied to palm oil to achieve the desired product characteristics. (5 marks)
b) Identify challenges the plant might face if choosing hydrogenation instead of interesterification. (4 marks)
c) Propose quality control measures to ensure the modified fats meet Kenyan food safety standards. (6 marks)
Suggested Approach
a) Interesterification involves rearranging the fatty acids on the glycerol backbone of palm oil triglycerides without altering their saturation levels. This process modifies melting behavior, resulting in fats with improved plasticity and spreadability, ideal for margarine and bakery applications. It avoids trans fat formation, aligning with health regulations and consumer preferences.
b) Challenges with hydrogenation include the formation of trans fatty acids, which are harmful to health and increasingly regulated. There is also the risk of over-hydrogenation leading to overly hard fats unsuitable for margarine. Additionally, hydrogenation requires precise control of reaction conditions and catalysts, increasing operational complexity.
c) Quality control measures should include testing for trans fat content using gas chromatography, monitoring melting point and solid fat index to ensure functional properties, and checking for oxidative stability to guarantee shelf life. The plant should also perform sensory evaluation for texture and taste and comply with Kenya Bureau of Standards (KEBS) edible fats specifications. Regular microbial testing and equipment sanitation must be enforced to maintain food safety.
Chapter Examination Questions
🔒 PDFDownload these examination questions, with worked answers
SECTION A (40 Marks) - Answer ALL Questions
Explain the process of hydrogenation and its significance in improving the shelf life of edible oils used by food manufacturers in Nairobi. (4 marks)
Describe how winterisation improves the quality of vegetable oils for salad dressings commonly produced in Kenyan hotels. (4 marks)
Discuss the principle of fractionation and its role in producing specialty fats for confectionery industries in Kenya. (4 marks)
Define interesterification and explain how it modifies the physical properties of fats used in bakery products. (4 marks)
What is the effect of plasticizing actions on the texture of margarine produced by Kenyan food processing firms? (4 marks)
Identify two advantages and two disadvantages of hydrogenation in edible oil processing. (4 marks)
Outline the main differences between winterisation and fractionation in edible oil refining. (4 marks)
Explain how interesterification can be used to create trans-fat free alternatives for cooking fats in Kenyan households. (4 marks)
Describe the impact of plasticizing agents on the crystallization behavior of fats used in chocolate manufacturing. (4 marks)
Discuss the environmental considerations that food technologists in Kenya must keep in mind when applying modification processes to edible lipids. (4 marks)
Section A - Answers
Hydrogenation is the chemical addition of hydrogen to unsaturated bonds in fatty acids, converting liquid oils to semi-solid fats. It improves shelf life by increasing oxidative stability, reducing rancidity in oils used by Nairobi-based food manufacturers.
Winterisation removes high melting point triglycerides by controlled cooling and filtration, preventing cloudiness in oils used in salad dressings, thus enhancing clarity and consumer appeal in Kenyan hotels.
Fractionation separates fats into solid and liquid components based on melting points, enabling production of specialty fats with tailored melting characteristics essential for confectionery products in Kenya.
Interesterification rearranges fatty acids on the glycerol backbone without altering saturation, modifying melting point and plasticity of fats, improving bakery product texture and shelf life.
Plasticizing actions reduce fat crystallinity and increase softness, resulting in margarine with spreadable texture preferred by Kenyan consumers.
Advantages: increased shelf life and improved texture; Disadvantages: formation of trans fats and potential nutritional concerns.
Winterisation removes waxes and high melting fats to improve clarity; fractionation separates fats into fractions with different melting ranges for specific applications.
Interesterification can rearrange fatty acids to produce fats with desirable melting points without creating trans fats, offering healthier cooking fat alternatives for Kenyan households.
Plasticizing agents interfere with fat crystal formation, promoting fine crystals and smoother texture important in chocolate manufacturing.
Environmental considerations include energy consumption, chemical waste disposal, and sustainability of raw materials used in fat modification processes.
SECTION B (60 Marks) - Answer any TWO Questions
Question 11 (Compulsory - 20 marks)
At a Nairobi-based bakery producing pastries using locally sourced vegetable oils, the management is considering modifying their fats to improve product quality and shelf life.
a) Explain how interesterification can be applied in this context and its expected benefits. (10 marks)
b) Discuss potential challenges and safety considerations the bakery should address when implementing hydrogenation in their fat processing. (10 marks)
Question 12 (20 marks)
Compare and contrast winterisation and fractionation as methods of edible oil modification, highlighting their processes, applications, and limitations in the Kenyan food industry.
Question 13 (20 marks)
Discuss the role of plasticizing actions in determining the functional properties of edible fats, with examples from margarine and chocolate production in Kenya.
Question 14 (20 marks)
Evaluate the health and environmental impacts of hydrogenation in edible oil processing and propose alternative modification techniques suitable for Kenyan food processors seeking to reduce trans fats.
Section B - Answers
11a) Interesterification rearranges fatty acids on triglycerides without creating trans fats, allowing the bakery to modify melting points and improve texture and shelf stability of their pastries. This process can enhance spreadability and mouthfeel, meeting consumer preferences in Nairobi. It also allows use of local oils with less desirable properties by improving functionality.
11b) Challenges include the need for specialized equipment and catalysts, managing reaction conditions to avoid unwanted by-products, and ensuring worker safety from chemical exposure. Hydrogenation can produce trans fats with health risks, requiring strict monitoring and compliance with food safety standards enforced by KEBS. Proper waste management of catalysts and hydrogen gas handling are critical safety concerns.
12) Winterisation involves controlled cooling to remove waxes and high melting components, improving oil clarity and stability, mainly used in salad oils and liquid applications. Fractionation separates fats into solid and liquid fractions by gradual cooling and filtration, producing specialty fats with tailored melting profiles for confectionery and bakery fats. Winterisation is simpler but less selective; fractionation allows precise fraction control but requires more energy and equipment. Both methods are essential in Kenyan food industries for product differentiation but have cost and operational implications.
13) Plasticizing actions reduce fat crystallinity and increase softness, critical for margarine spreadability and chocolate smoothness. In margarine, plasticizers enable easy spreading at refrigeration temperatures, enhancing consumer satisfaction. In chocolate, plasticizing agents promote uniform fat crystal formation, preventing grainy texture and improving mouthfeel. Kenyan producers leverage these properties to meet market demands for quality and consistency in fats used in confectionery and baking.
14) Hydrogenation extends shelf life but produces trans fats linked to cardiovascular diseases, raising health concerns among Kenyan consumers. Environmentally, it involves high energy use and catalyst disposal challenges. Alternatives like interesterification and fractionation can modify fats without trans fats, promoting healthier products. Food processors in Kenya are encouraged to adopt these greener technologies alongside consumer education on healthy fat choices to reduce trans fat consumption.
TVET CDACC - Fats And Oils Processing Occupational Standards
Chapter Practical Activities
Practical 1: Hydrogenation of Vegetable Oil Sample
Time: 3 Hours | Type: Individual
Resources Required:
Hydrogenation reactor or small-scale hydrogenation apparatus
Vegetable oil sample (e.g., sunflower oil 500ml)
Hydrogen gas cylinder with regulator
Nickel catalyst
Thermometer (range 0-300°C)
Magnetic stirrer
Stopwatch
Lab coat, gloves, safety goggles
At a food processing laboratory within the Kenya Industrial Research and Development Institute (KIRDI), candidates will simulate partial hydrogenation of vegetable oil to increase melting point for margarine production.
Tasks:
i. Prepare the hydrogenation apparatus and ensure all connections are secure
ii. Charge the reactor with vegetable oil and nickel catalyst as per standard ratios
iii. Introduce hydrogen gas under controlled pressure and maintain temperature between 120-150°C
iv. Monitor and record the reaction time, temperature, and degree of hydrogenation achieved
Assessor Observation Criteria:
[ ] Correct setup and safe handling of hydrogenation apparatus
[ ] Accurate measurement and addition of catalyst and oil
[ ] Maintenance of reaction temperature within specified range
[ ] Proper recording and interpretation of reaction parameters
Practical 2: Winterisation of Edible Oil to Remove High-Melting Triglycerides
Time: 2 Hours | Type: Individual
Resources Required:
Refrigerated centrifuge or cold room (temperature control to 0-10°C)
Sample of crude vegetable oil (500ml)
Glass beakers (1L capacity)
Thermometer (range -10 to 30°C)
Filter paper and vacuum filtration setup
Lab coat, gloves, safety goggles
At a margarine manufacturing facility in Thika, students will perform winterisation to improve oil clarity and stability by removing waxes and high melting point fractions.
Tasks:
i. Cool the vegetable oil sample gradually to 5°C and hold for 4 hours
ii. Separate the solidified fractions by filtration or centrifugation
iii. Collect and weigh the winterised oil and solid fraction
iv. Record temperature changes and calculate percentage yield of winterised oil
Assessor Observation Criteria:
[ ] Controlled cooling of oil to specified temperature
[ ] Effective separation of solid fractions using filtration or centrifuge
[ ] Accurate measurement of oil and solid fractions
[ ] Clear and complete recording of temperature and yield data
Practical 3: Fractionation of Palm Oil by Dry Fractionation Method
Time: 4 Hours | Type: Individual
Resources Required:
Palm oil sample (500ml)
Temperature-controlled water bath or jacketed vessel
Stirring rod
Ice bath
Filter paper and funnel
Analytical balance (precision 0.01g)
Lab coat, gloves, safety goggles
In a food processing lab at a tea factory in Kericho, candidates fractionate palm oil into solid stearin and liquid olein fractions using dry fractionation to produce specialty fats.
Tasks:
i. Heat palm oil sample to 70°C and stir to ensure uniformity
ii. Cool oil slowly to 25°C over 2 hours to induce crystallization
iii. Separate solid stearin by filtration and collect liquid olein fraction
iv. Weigh both fractions and calculate their percentage relative to original oil
Assessor Observation Criteria:
[ ] Proper temperature control during heating and cooling phases
[ ] Effective stirring and mixing of oil sample
[ ] Successful separation and collection of fractions
[ ] Accurate weighing and calculation of fraction yields
Practical 4: Interesterification of Edible Oil Blends in Laboratory Scale
Time: 3 Hours | Type: Individual
Resources Required:
Oil blend sample (e.g., soybean and palm oil, 500ml total)
Sodium methoxide catalyst
Reaction vessel with stirring and temperature control, pH meter
Neutralizing agents (citric acid solution)
Thermometer (0-150°C)
Lab coat, gloves, safety goggles
At a food science department within Jomo Kenyatta University of Agriculture and Technology (JKUAT), candidates will perform chemical interesterification to modify melting characteristics of oil blends.
Tasks:
i. Mix oil blend with sodium methoxide catalyst under nitrogen atmosphere
ii. Maintain reaction temperature at 90°C while stirring for 1 hour
iii. Neutralize the reaction mixture and separate glycerol byproduct
iv. Analyze and record changes in physical properties of modified oil
Assessor Observation Criteria:
[ ] Correct preparation and handling of catalyst and oil blend
[ ] Maintenance of reaction temperature and stirring conditions
[ ] Proper neutralization and separation of byproducts
[ ] Accurate recording of physical property changes
Practical 5: Plasticizing Action of Oil Blends for Bakery Fat Preparation
Time: 2 Hours | Type: Group of 2
Resources Required:
Samples of hydrogenated fat, liquid oil, and interesterified fat blends (each 250g)
Plasticizing mixer or paddle mixer
Penetrometer or texture analyzer
Thermometer (0-50°C)
Mixing bowls and spatulas
Lab coat, gloves
At a bakery in Nakuru, candidates will investigate the plasticizing effect of different fat blends used in pastry production to determine suitability for dough handling.
Tasks:
i. Prepare fat blends in specified proportions and mix thoroughly at 25°C
ii. Measure plasticity using penetrometer or texture analyzer
iii. Record and compare results for each blend
iv. Discuss implications of plasticity on bakery product quality
Assessor Observation Criteria:
[ ] Accurate preparation and mixing of fat blends
[ ] Correct use of penetrometer or texture analyzer
[ ] Clear recording and comparison of plasticity results
[ ] Ability to relate plasticity findings to bakery applications
Practical 6: Monitoring Iodine Value Changes During Hydrogenation
Time: 2 Hours | Type: Individual
Resources Required:
Oil sample undergoing hydrogenation
Iodine value titration kit (Wijs method reagents)
Burette, conical flasks, pipettes
Analytical balance (0.001g precision)
Lab coat, gloves, safety goggles
In a food quality control lab at a dairy processing company in Kisumu, candidates monitor iodine value to assess degree of unsaturation before and after hydrogenation.
Tasks:
i. Prepare oil samples before and after hydrogenation for iodine value analysis
ii. Perform iodine value titration using Wijs method
iii. Calculate iodine values and interpret degree of hydrogenation
iv. Record results and recommend process adjustments if necessary
Assessor Observation Criteria:
[ ] Correct sample preparation and handling
[ ] Accurate performance of titration procedure
[ ] Precise calculation of iodine values
[ ] Logical interpretation relating iodine value to hydrogenation level
Practical 7: Separation of Oil Fractions Using Solvent Fractionation
Time: 3 Hours | Type: Individual
Resources Required:
Crude oil sample (500ml)
Acetone or hexane solvent (analytical grade)
Separatory funnel
Rotary evaporator or hot plate for solvent recovery
Glass beakers and flasks
Lab coat, gloves, safety goggles
At a vegetable oil refinery in Mombasa, candidates simulate solvent fractionation to separate high melting point fractions from liquid oil.
Tasks:
i. Mix oil sample with solvent in appropriate ratio and cool to precipitate solids
ii. Separate solid and liquid phases using separatory funnel
iii. Recover solvent from liquid fraction by evaporation
iv. Weigh fractions and calculate separation efficiency
Assessor Observation Criteria:
[ ] Safe handling of solvents and oil samples
[ ] Effective phase separation using separatory funnel
[ ] Proper solvent recovery techniques
[ ] Accurate weighing and calculation of fractionation yield
Practical 8: Determination of Slip Melting Point for Modified Fats
Time: 1 Hour | Type: Individual
Resources Required:
Samples of hydrogenated, winterised, and interesterified fats
Slip melting point apparatus or capillary tube setup
Thermometer (0-100°C)
Water bath with temperature control
Lab coat, gloves
In the food lab at Kenyatta National Hospital nutrition department, candidates determine slip melting points to assess suitability of fats for therapeutic foods.
Tasks:
i. Prepare fat samples in capillary tubes
ii. Heat samples gradually in water bath and observe melting behavior
iii. Record temperature at which fat starts to melt (slip melting point)
iv. Compare melting points among modified fats and report findings
Assessor Observation Criteria:
[ ] Proper preparation of samples in capillary tubes
[ ] Controlled heating and accurate temperature measurement
[ ] Correct observation and recording of slip melting points
[ ] Clear comparison and reporting of results
Practical 9: Quality Testing of Fractionated Oils for Cloud Point
Time: 1.5 Hours | Type: Individual
Resources Required:
Fractionated oil samples (olein fraction)
Cloud point apparatus or refrigerated chamber
Test tubes or clear bottles
Thermometer (range -10 to 30°C)
Lab coat, gloves
At a vegetable oil packing plant in Eldoret, candidates test cloud point to ensure oil clarity during storage and distribution.
Tasks:
i. Place oil samples in test tubes and cool gradually in refrigerated chamber
ii. Observe and record temperature at which cloudiness appears
iii. Repeat test for multiple samples for consistency
iv. Interpret results regarding oil quality and suitability for market
Assessor Observation Criteria:
[ ] Correct setup for cloud point determination
[ ] Accurate temperature control and observation
[ ] Consistent recording of cloud point temperatures
[ ] Logical interpretation related to oil quality standards
Practical 10: Preparation and Evaluation of Plasticized Fat Blend for Margarine
Time: 3 Hours | Type: Group of 3
Resources Required:
Hydrogenated fat, liquid oil, interesterified fat (quantities for 1kg blend)
Mixer or paddle blender
Texture analyzer or penetrometer
Refrigerator
Lab coat, gloves
In a food technology workshop at a Nairobi-based margarine manufacturer, candidates will prepare a plasticized fat blend and evaluate its physical properties relevant to spreadability.
Tasks:
i. Weigh and blend fats in specified proportions to prepare margarine fat base
ii. Chill the blend in refrigerator to solidify
iii. Measure plasticity and texture using appropriate instrument
iv. Record data and suggest improvements to blend formulation
Assessor Observation Criteria:
[ ] Accurate weighing and blending of fat components
[ ] Proper chilling and sample preparation
[ ] Correct use of texture analysis equipment
[ ] Comprehensive recording and interpretation of results
