ICAR AICE-JRF/SRF Milk & Milk Products Technology: practice questions

Question 1 · hard

Which statement about the freezing point of milk is correct?

1. It varies widely between cows because it follows the fat content of each cow's milk
2. It falls further below zero when water is added to milk, which is exactly how cryoscopes detect watering
3. It is set mainly by casein micelles, so it changes sharply when casein content changes
4. It is nearly constant, around -0.52 to -0.54 degrees C, because it follows the osmotic pressure of blood

Question 2 · medium

Which fatty acid is characteristic of ruminant milk fat and underlies the Reichert-Meissl value?

1. Linoleic acid (C18:2)
2. Lauric acid (C12:0)
3. Butyric acid (C4:0)
4. Palmitic acid (C16:0)

Question 3 · medium

A UHT process holds milk for 4 s at 140 degrees C. The target spore has D140 = 0.8 s. How many decimal reductions are achieved?

1. 5
2. 0.2
3. 50
4. 3.2

Question 4 · medium

Why is sweetened condensed milk seeded with very fine lactose powder during cooling?

1. To lower viscosity so the product pours easily from the can
2. To supply nutrients that speed up the lactic fermentation
3. To form many tiny lactose crystals so the product does not feel sandy
4. To raise the sugar ratio above 64.5% and prevent mould growth

Question 5 · hard

Why does ghee develop a granular texture when cooled slowly?

1. High-melting glycerides crystallise slowly into large grains in liquid fat
2. Residual casein particles act as grains that settle as the ghee cools
3. Lactose crystallises out of the fat phase during slow cooling
4. Residual moisture droplets freeze into small ice crystals inside the solid fat during slow cooling

Question 6 · medium

During churning of cream into butter, which change takes place in the emulsion?

1. Casein micelles coagulate and trap the fat as a protein gel
2. Water-in-oil emulsion of cream inverts to oil-in-water emulsion of butter
3. Oil-in-water emulsion of cream inverts to water-in-oil emulsion of butter
4. Fat globules melt completely and recrystallise as a single phase

Question 7 · hard

A cooperative wants to mechanise khoa production while keeping its traditional texture. Which equipment is most suited?

1. A scraped-surface heat exchanger or conical vat with rotating scrapers
2. A falling-film evaporator followed by a spray dryer, giving a free-flowing khoa powder
3. A plate heat exchanger operated at 72 degrees C for 15 seconds
4. A cheddaring machine followed by a mechanical press

Question 8 · medium

What is the basis of the protocooperation between the two yoghurt bacteria?

1. The lactobacillus makes diacetyl; the streptococcus converts diacetyl to acetaldehyde
2. The streptococcus releases bacteriocins that kill phages attacking the lactobacillus
3. The lactobacillus releases peptides and amino acids; the streptococcus supplies formic acid and CO2
4. The streptococcus ferments only galactose while the lactobacillus ferments only glucose, producing ethanol and CO2

Question 9 · hard

Using the Van Slyke formula, Y = (0.93F + C - 0.1) x 1.09 / (1 - W), estimate Cheddar yield per 100 kg milk with 3.6% fat, 2.5% casein and cheese moisture of 37%.

1. About 9.9 kg
2. About 16.9 kg
3. About 10.4 kg
4. About 6.3 kg

Question 10 · medium

What does an ATP bioluminescence swab of a cleaned surface detect?

1. Mineral scale remaining after the acid step
2. Detergent residues left after the final rinse
3. Viable Listeria monocytogenes only, counted within a few minutes on the surface
4. Organic residue from food soil and microbes, not specific organisms