ICAR AICE-JRF/SRF 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 · Processed cheese and cheese spreads: emulsifying salts · hard

A processed-cheese batch uses 400 kg of natural cheese (38% moisture) and 10 kg of dry emulsifying salt. How much water must be added for a final moisture of 45%, assuming no evaporation?

1. 59.1 kg
2. 163.3 kg
3. 28.0 kg
4. 69.1 kg

3 · Coagulants: calf rennet, microbial, fermentation-produced chymosin, plant · hard

A cheesemaker switches from calf chymosin to a more proteolytic microbial coagulant at the same clotting dose for long-ripened Cheddar. What is the most likely result?

1. No effect, since the clotting dose was matched exactly
2. Faster lactose fermentation by the coagulant and a sharp rise in acidity in the vat
3. A large rise in yield because more casein stays in the curd
4. A small fall in yield and more risk of bitterness during ripening

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 · 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

6 · 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

7 · Salting: dry, brine and its effect · hard

A Cheddar has low salt-in-moisture. Which ripening defect is most likely?

1. Mould growth inside the cheese, because a low salt level draws oxygen into the paste
2. Late blowing by clostridia, because salt has no role in spore control
3. Bitter, acid, pasty cheese from excessive starter and coagulant activity
4. Dry, crumbly, slow-ripening cheese with a pronounced salty taste

8 · Ripening and accelerated ripening · hard

Why are exogenous proteinases added to milk a poor way to accelerate Cheddar ripening?

1. Most is lost in whey; what stays risks bitterness and lower yield
2. Proteinases are not legal in any country as food processing aids
3. Proteinases ferment lactose and make the curd far too acid to press
4. Proteinases are destroyed by salt, so they never reach the cheese interior

9 · Varieties: Cheddar, Gouda, Swiss types, Mozzarella, Parmesan, blue and soft cheeses · medium

Small eyes in Gouda and Edam are produced mainly by:

1. Air trapped mechanically during dry salting of curd
2. Yeasts on the rind producing gas that diffuses inward
3. Citrate-fermenting mesophilic starter strains producing CO2
4. Propionibacteria held in a warm room at about 22 °C for weeks

10 · 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