ICAR AICE-JRF/SRF (PhD): Dairy Chemistry, Dairy Microbiology, Dairy Technology, Dairy Engineering · India · NTA for ICAR
Original practice questions written to the published syllabus · not past papersEvaporated and sweetened condensed milk, milk powders and their functional properties, storage and defects.
In the exams: ICAR AICE subject 37 Units 1 and 3 and subject 34 Unit 6; ICAR AIEEA-PG group 16 (changes in manufacture and storage of milk powder)
ICAR AICE-JRF/SRF (PhD) — Dairy Chemistry (34) and Dairy Technology (37)
Subject 34 Unit 6: heat stability, age gelation of UHT and concentrated milk, compositional differences between condensed and evaporated milk, structure and properties of dried milk and instant powder, spoilage of powder. Subject 37 Unit 3: advances in drying, freeze drying, glass transition, water activity and sorption, hurdle technology.
How our questions for ICAR AICE-JRF/SRF spread across the units of Concentrated & Dried Dairy Products. Difficulty: 1 easy, 33 medium, 23 hard.
| Sweetened condensed milk: sugar ratio and lactose crystallisation | 6 | |
| Spray drying of milk: process and powder properties | 6 | |
| Evaporated milk: process and heat stability | 6 | |
| Heat classification of milk powders: WPNI | 5 | |
| Dairy whiteners and filled milk powders | 5 | |
| Water activity, sorption and glass transition in powders | 5 | |
| Powder fires and explosions: safety | 5 | |
| Defects of condensed milks | 4 | |
| Roller drying | 4 | |
| Whole, skim and instant milk powders | 4 | |
| Agglomeration and instantising | 4 | |
| Powder storage, caking and Maillard browning | 3 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A fat-filled milk powder of 26% fat is made from skim milk powder (1% fat) and vegetable fat, ignoring moisture. Per 100 kg of product, how much vegetable fat is used?
B. 25.25 kg
Fat: 0.01S + F = 26 with S + F = 100, so 0.99F = 25, F = 25.25 kg and S = 74.75 kg. 26.00 kg ignores the fat in the powder; 26.26 kg divides by 0.99 without subtracting the powder fat; 73.74 kg is close to the powder mass, not the fat.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Concentrating milk lowers its heat stability mainly because:
C. Calcium ions and protein become more concentrated and pH falls
Higher calcium activity and protein concentration with a small pH drop favour coagulation on heating.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
The heat coagulation time of milk is the time to visible coagulation at a set temperature. It depends most strongly on:
D. pH
Milk shows a characteristic heat coagulation time–pH profile.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Age gelation of evaporated milk during storage is accelerated by:
A. Low forewarming and high storage temperature
Protein interactions build slowly, faster at warm temperatures and with less forewarming.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Lecithin is sprayed onto agglomerated whole milk powder to:
C. Make the particle surface wettable in cold water
Lecithin's hydrophilic groups counter surface free fat.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Why is WPNI alone not enough to guarantee a powder's suitability for recombined evaporated milk?
C. Heat stability depends on more than whey denaturation
Salt balance and other factors affect heat stability, so a separate test is used.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Why can WPNI vary with season even at constant processing?
D. Milk whey protein content varies with lactation and season
WPNI reflects initial whey protein as well as heat history.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
In straight-through agglomeration, fines from the cyclones are:
B. Returned to the atomiser zone to meet moist droplets
Fines stick to moist droplets and build agglomerates.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Why is dairy whitener more prone to caking than skim milk powder?
A. Sugar makes it hygroscopic and lowers its glass transition
Sugars plasticise and attract water.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Which salt is used in creamers to prevent feathering?
C. Dipotassium phosphate
Buffering phosphates raise pH and bind calcium; calcium salts would worsen feathering.
Further reading: Walstra, Wouters and Geurts, Dairy Science and Technology
Ten here, 57 in the app. The Laisha app has every practice question we have written to ICAR AICE-JRF/SRF in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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