ICAR AIEEA-PG / PGS — Code 18 Food Science Technology · India · ICAR through the National Testing Agency
Original practice questions written to the published syllabus · not past papersThe dairy course taught inside food technology degrees: milk as a raw material, fluid-milk processing, the main dairy products, and dairy ingredients (powders, whey and milk proteins) used across the food industry. For depth in dairy chemistry, microbiology and plant engineering see the Dairy Technology track; for Indian traditional dairy products and FSSAI dairy standards see Veterinary's milk-products-technology.
In the exams: GATE XE-G and XL-U Section 3 (milk and milk products processing: pasteurisation, sterilisation, cream, butter, ghee, ice cream, cheese, milk powder); ICAR AIEEA-PG Code 18 Unit III; ICAR AICE 35.a Unit 3
ICAR AIEEA-PG / PGS — Code 18 Food Science Technology
Unit III names dairy technology. Expect MCQs on milk composition and properties, platform tests (COB, alcohol, MBRT), the Gerber test and SNF formulas, pasteurisation standards, butter and ghee methods, cheese types, fermented milks, ice cream, condensed milk, milk powders and whey products.
How our questions for ICAR AIEEA-PG / PGS spread across the units of Dairy Science & Technology for Food Technologists. Difficulty: 21 easy, 53 medium, 12 hard.
| Cheese: coagulation, cheddar and mozzarella principles | 8 | |
| Homogenisation | 7 | |
| Pasteurisation, UHT and sterilised milks | 7 | |
| Ice cream and frozen desserts | 7 | |
| Milk powders and infant formula basics | 7 | |
| Whey and milk-protein ingredients | 7 | |
| Dairy plant cleaning and sanitation | 7 | |
| Composition and physicochemical properties of milk | 6 | |
| Milk reception, quality testing and platform tests | 6 | |
| Clarification, separation and standardisation | 6 | |
| Cream, butter and ghee | 6 | |
| Fermented milks | 6 | |
| Condensed and evaporated milk | 6 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
The most sensitive routine test for detecting added water in milk is
D. Freezing point by cryoscope
Milk's freezing point is very constant, close to −0.52 to −0.54 °C, and added water raises it toward 0 °C. Fat and acidity do not reveal watering reliably, and the lactometer is fooled by combined skimming and watering.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Compared with cow milk, buffalo milk generally has
D. Higher fat
Buffalo milk commonly carries about 6–8% fat, much more than cow milk, and somewhat more protein and SNF. It contains casein, and lactose remains a major solid.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
The clot-on-boiling test at the milk reception platform detects
B. High acidity or colostrum
Milk with high developed acidity or containing colostrum clots on boiling. Water needs a cryoscope or lactometer, residues need specific tests, and fat needs the Gerber or an analyser.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
In the Gerber fat test, amyl alcohol is added mainly to
B. Help the fat separate clearly
Amyl alcohol aids clean separation of the fat column and prevents charring of fat; sulphuric acid dissolves the proteins. It neither neutralises the acid nor colours the fat.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
1000 kg of milk at 4.0% fat is separated into cream of 40% fat and skim of 0.05% fat. The mass of cream is about
D. 98.9 kg
Cream = 1000 × (4.0 − 0.05) ÷ (40 − 0.05) = 98.9 kg. 100 kg assumes skim has no fat (1000 × 4 ÷ 40); 901 kg is the skim; 90.1 kg is a decimal slip on the skim.
Further reading: Tetra Pak, Dairy Processing Handbook
Milk is separated warm, commonly at 40–50 °C or above, mainly because
D. Fat is liquid and viscosity is lower
Warm milk has liquid fat and lower viscosity, so globules separate faster and more completely. Separation temperatures are not a kill step, and lactose and casein do not change in these ways.
Further reading: Tetra Pak, Dairy Processing Handbook
The flow diversion valve of an HTST pasteuriser
C. Diverts under-heated milk
If the temperature at the end of the holding tube falls below the legal minimum, the valve diverts the milk back to the balance tank for reheating. It does not standardise, control fillers or de-aerate.
Further reading: Tetra Pak, Dairy Processing Handbook
Chymosin coagulates milk by cleaving
C. κ-casein
Chymosin specifically cleaves κ-casein at Phe105–Met106, removing the stabilising caseinomacropeptide so the micelles aggregate with calcium. It does not act on the other proteins or on lactose.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
The buttery aroma of cultured buttermilk comes from
A. Diacetyl
Citrate-fermenting lactococci and Leuconostoc produce diacetyl, the buttery aroma. Acetaldehyde is the key yoghurt flavour; ethanol and propionic acid belong to other fermentations.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
100 L of ice cream mix gives 190 L of ice cream. The overrun by volume is
A. 90%
Overrun = (190 − 100) ÷ 100 × 100 = 90%. 190% is the final volume as a percentage; 47% divides 90 by 190; 53% is the mix share of the ice cream.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
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