Afs 2203:Food Analysis Question Paper
Afs 2203:Food Analysis
Course:Bachelor Of Science In Food Science And Nutrition
Institution: Meru University Of Science And Technology question papers
Exam Year:2013
QUESTION ONE (30 MARKS)
a) You are considering the use of a new method to measure compound X in your food products. List 5 factors you will consider before adopting this new method in your quality assurance lab. (10 Marks) b) Method A used to quantitate a particular food component was reported to be more specific and accurate than method B, but method A had lower precision. Explain what this means. (7 Marks) c) Distinguish between sampling for attributes Vs sampling for variables. (6 Marks) d) Briefly describe the 3 sources of error in food analysis. (3 Marks) e) Differentiate the following: (4 Marks) I. Consumer risk II. Producer risk
QUESTIONTWO (20 MARKS)
a) Identify 5 factors that one would need to consider when choosing a moisture content analysis method for a specific food product (10 Marks) b) You have the following gravimetric result: - Weight of pan and liquid sample = 4.6274g - Weight of dried pan and glass disc = 1.0376g - Weight of pan and dried sample = 1.7321g What was the moisture content of the sample and what is the percent solids (6 Marks)
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c) Discuss 2 advantages of using gravimetric methods as opposed to thermo gravimetric methods. (4 Marks)
QUESTION THREE (20 MARKS)
a) Identify 4 potential sources of error in the preparation of samples for ash analysis and describe a way to overcome each. (8 Marks) b) Discuss the following (8 Marks) I. Dry aching II. Wet aching
c) Discuss the “Gerber Method” for milk fat analysis (4 Marks)
QUESTION FOUR (20 MARKS)
a) Discuss 5 important considerations when selecting solvents to be used in fat analysis (10 Marks) b) The following data were obtained when an extruded breakfast cercal was analyzed for fiber by food science students:
Sample weight (mg) 1002.8 Residue weight (mg) 151.9 Pertain weight 13.1 Ash weight (mg) 21.1 Blank weight 6.1 Resistant starch (mg) 35.9
What is percent total fibre (4 Marks) i. Without corrections for resistant starch ii. With correction for resistant starch c) A sample of 10g fruit pulp is mixed with 20ML distilled water and the mixture brought to boiling and cooled quickly. It is then titrated with 0.1N NaOH solution, 6 ML being obtained at the end point. Calculate the total titratable acidity of the pulp as percent citric acid.
Hitn: CH2C00HC(0H)COOH CH2COOH
?? = 1 ?? = 12 0 = 16
(6 Marks)
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QUESTION FIVE (20 MARKS)
a) Discuss the following as used in carbohydrate assay (10 Marks) i. Molisch’s tests ii. Benedict’s test iii. Seliwanoh’s tests iv. Iodine test v. Bial b) Food science students from MUST were analyzing crude protein content of beans in duplicate using the Kyeldhal method. The following were their data: Moisture content = 8% Weight of sample 1 = 1.015g Weight of sample 2 = 1.025g Normality of HCL used in titration = 0.1142N HCL used for sample 1 = 22.0 ml HCL used for sample 2 ` = 22.5 ml HCL used for reagent blank = 0.2 ml
Calculate crude protein content on both wet and dry weight basis of these beans. Assume that beans protein contains 17.5% nitrogen. (10 Marks)
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