ICAR AIEEA-PG Cheese Science & Technology: practice questions

1 · Mechanised and UF-based cheese making · medium

Ultrafiltration of 1,200 kg of milk (3.3% protein) gives 240 kg of retentate. Assuming complete protein retention, what is the protein content of the retentate?

1. 13.2%
2. 0.66%
3. 16.5%
4. 19.8%

2 · Salting: dry, brine and its effect · medium

How much salt must be dissolved in 1,000 kg of water to make a brine of 20% NaCl (w/w)?

1. 250 kg
2. 800 kg
3. 200 kg
4. 166.7 kg

3 · Fresh cheeses: cottage, cream cheese, quark, queso fresco, paneer · hard

Buffalo milk (100 kg, 6.0% fat, 9.0% SNF) is made into paneer. Assume 90% of the fat and 60% of the SNF are recovered and the paneer has 55% moisture. What mass of paneer is expected?

1. 19.6 kg
2. 24.0 kg
3. 10.8 kg
4. 30.0 kg

4 · Rennet coagulation and gel formation · medium

After chymosin action, which kappa-casein fragment leaves with the whey?

1. Caseinomacropeptide (residues 106–169)
2. Gamma-1-casein fragment (residues 29–209)
3. Para-kappa-casein (residues 1–105)
4. Alpha-s1-I casein (residues 24–199)

5 · Rennet coagulation and gel formation · easy

The kappa-casein 'hairy layer' stabilises casein micelles mainly by:

1. Steric and electrostatic repulsion between micelles
2. Hydrogen bonds to lactose dissolved in the serum
3. Binding all the calcium so none is free in milk
4. Covalent bonds holding micelles to the fat globules

6 · Cutting, cooking and syneresis · medium

Why is part of the whey replaced by water during Gouda making?

1. To add calcium from the water so the curd fuses more firmly in the press
2. To lower the fat content of the curd so that it meets the fat-in-dry-matter limit set by law
3. To dilute the coagulant so that it stays active for longer in the curd
4. To remove lactose so that less acid forms and the cheese keeps a higher pH

7 · Cheddaring, pasta filata stretching and other curd treatments · medium

Why will Mozzarella curd not stretch if its pH is too high?

1. Too much colloidal calcium phosphate has dissolved, so the curd turns to liquid
2. Too much salt has been absorbed from the cooking water, firming the curd
3. Too little calcium phosphate has dissolved, so the curd is not plastic
4. The coagulant has been destroyed, so the protein network cannot form fibres

8 · Processed cheese and cheese spreads: emulsifying salts · medium

Which group lists commonly used emulsifying salts for processed cheese?

1. Sodium citrates and sodium mono-, di- and polyphosphates
2. Sodium benzoate, potassium sorbate and nisin only
3. Calcium chloride, calcium lactate and calcium carbonate salts
4. Sodium nitrate, potassium nitrate and lysozyme

9 · Cheese defects and grading · easy

Late blowing in Gouda and Emmental is caused by:

1. Coliform bacteria fermenting lactose in the first day after the cheese is made
2. Yeasts on the rind fermenting the salt into gas during the brining stage
3. Propionic bacteria producing too many round eyes in the warm ripening room
4. Clostridium tyrobutyricum spores fermenting lactate to butyrate and gas

10 · Mechanised and UF-based cheese making · medium

Why does ultrafiltration raise cheese yield?

1. Fat globules are broken down so that more fat dissolves in the curd
2. Casein is converted into whey protein, which binds more water
3. Lactose is concentrated in the curd and adds to the cheese mass
4. Whey proteins are retained with casein and fat instead of being lost in whey