1. _______ is the principal contributor to sunlight flavor.
a) Methional
b) Ethane
c) Heptanes
d) Acid
Discussion
Explanation: Methional or 3-mercapto-methylpropionaldehyde is the principal contributor to sunlight flavor, as this particular flavor is called. It is a typical off-flavor found in milk
2. What is the process of breakdown of fat into glycerol and free fatty acid called?
a) Addition
b) Reduction
c) Oxidation
d) Lipolysis
Discussion
Explanation: The breakdown of fat into glycerol and free fatty acids is called lipolysis. Lipolysed fat has a rancid taste and smell, caused by the presence of low molecular free fatty acids.
3. Enzyme responsible for Lipolysis is ____________
a) Pepsin
b) Pectinase
c) Lipases
d) Rennin
Discussion
Explanation: Lipolysis is caused by the action of lipases. Lipolysis is encouraged by high storage temperatures.
4. The purpose of heat treatment on milk is ___________
a) Kill pathogenic microorganism
b) Heat milk
c) Evaporation
d) Taste enhancement
Discussion
Explanation: Heat treatment on milk aims to kill pathogenic microorganism. Heat treatment of milk also enhances its shelf life.
5. The fat globules in milk when heated to 74℃ show which of the following phenomenon?
a) Frothing
b) Evaporation
c) Cream plug formation
d) Condensation
Discussion
Explanation: It has been shown that when milk is pasteurized at 70 – 80°C for 15 seconds, the cream plug phenomenon is already evident at 74°C
6. ________ is recommended in order to avoid cream plug formation.
a) Cooling
b) Freezing
c) Churning
d) Homogenization
Discussion
Explanation: Homogenization is practiced to avoid cream plug formation. Cream plug formation leads to blockage in pipes and tubes.
7. What is the result of heat treatment on proteins?
a) Denaturation
b) Blanching
c) Spore formation
d) Froth formation
Discussion
Explanation: Proteins on heat treatment undergo denaturation. Denaturing of protein leads to off flavor.
8. Denature Protein contributes to an improvement in the quality of which of the following products?
a) Cultured milk product
b) Milk
c) Ice cream
d) Cream
Discussion
Explanation: In milk intended for cultured milk products (yogurt, etc.), the whey protein denaturation and interaction with casein obtained at 90 – 95°C for 3 – 5 minutes will contribute to improved quality in the form of reduced syneresis and improved viscosity.
9. Effect of Heat treatment (Temperature above 100℃) on Lactose:
a) Greenish color
b) Bluish color
c) Brownish color
d) Reddish color
Discussion
Explanation: Lactose undergoes changes more readily in milk than in the dry state. At temperatures above 100 °C a reaction takes place between lactose and protein, resulting in a brownish color.
10. The lactulose content ______ with increased intensity of the heat treatment.
a) Decrease
b) Increase
c) Remains same
d) First increase and then decrease
Discussion
Explanation: The lactulose content thus increases with the increased intensity of the heat treatment. It may lead to denaturation of proteins.