ICAR AICE-JRF/SRF Whey & Dairy By-product Utilisation: practice questions

1 · Types and composition of whey · medium

Which whey protein makes up roughly half of total whey protein?

1. Bovine serum albumin, carried over from blood
2. Beta-lactoglobulin
3. Alpha-lactalbumin, the main whey protein of human milk
4. Immunoglobulin G, which dominates colostrum

2 · Whey disposal problem: BOD and COD · medium

Why is excessive land application of acid whey particularly harmful?

1. Its lactose sterilises the soil permanently at once
2. Its minerals and acidity salinise and damage soils
3. Its fat forms an impermeable layer across the field
4. Its protein content blocks all plant roots from water uptake

3 · Whey disposal problem: BOD and COD · hard

COD rather than BOD is often used to design anaerobic digesters for whey because:

1. COD measures only the protein, which makes the methane
2. BOD cannot be measured on any dairy effluent at all
3. Methane yield is directly related to COD removed
4. BOD is always higher than COD for whey

4 · Whey beverages and whey cheese: ricotta, ricotta-type and brown whey cheese · hard

Why must the concentrate for brown whey cheese be cooled with stirring?

1. To control lactose crystallisation and avoid sandiness
2. To stop Maillard browning by removing the reducing sugars from it
3. To make the fat crystallise as large grains
4. To dissolve the whey protein back into the serum

5 · Whey powder and demineralised whey · easy

Why is whey concentrate pre-crystallised before spray drying?

1. To denature the whey proteins before they reach the dryer
2. To remove all the minerals from the whey concentrate
3. To increase the fat content of the powder
4. To make a non-caking, less hygroscopic powder

6 · Whey powder and demineralised whey · medium

Highly demineralised whey (D90) is mainly used in:

1. Infant formula
2. Processed meat brines
3. Biogas digesters
4. Animal feed for adult cattle

7 · Lactose manufacture and refining · easy

Edible lactose crystallises from concentrated whey or permeate mainly as:

1. Lactulose crystals
2. Amorphous glassy lactose
3. Alpha-lactose monohydrate
4. Beta-lactose anhydrous above 100 °C

8 · Buttermilk and its phospholipids · medium

Buttermilk powder is used in bakery mainly as:

1. A sugar replacer
2. A preservative against mould
3. An emulsifier and flavour ingredient
4. A leavening agent

9 · Permeate utilisation · hard

Why does the economics of a WPC plant depend on permeate use?

1. Permeate is the larger stream and has a high BOD
2. Permeate can be discharged freely to drains
3. Permeate is worth more than WPC per kilogram
4. Permeate contains most of the whey protein

10 · Fermentation of whey: ethanol, biogas, single-cell protein · easy

Which yeast is commonly used to ferment whey lactose to ethanol?

1. Penicillium roqueforti
2. Kluyveromyces marxianus
3. Lactobacillus bulgaricus
4. Saccharomyces cerevisiae without modification