Food Processing Unit Operations Multiple Choice Questions on “Process Engineering Applications – Dairy Industry”.
1. What is other name for batch pasteurization?
a) Vat Pasteurization
b) HTST pasteurization
c) UHT pasteurization
d) Cold pasteurization
Answer: a
Clarification: Vat Pasteurization is also known as the holding method or batch pasteurization. Every particle of milk or cream is heated in equipment at 63°C and hold for 30 minutes.
2. What happens when milk is pasteurized?
a) Reduces the bacterial population
b) Destroys spores
c) Impart color
d) Impart flavor
Answer: a
Clarification: Pasteurization is not similar to sterilization. Pasteurization reduces the bacterial population of a liquid and destroys the organisms that may cause spoilage and human disease. Spores are not affected by the pasteurization process.
3. What happens when milk is sterilized?
a) Reduces the bacterial population
b) Destroys spores
c) Impart color
d) Impart flavor
Answer: b
Clarification: Pasteurization is not similar to sterilization. Spores are not affected by the pasteurization process. But the sterilization process destroys the spores of the bacteria by inactivating them.
4. What is the chilling temperature of milk?
a) 1-2°C
b) 3-4°C
c) 5-6°C
d) 6-7°C
Answer: b
Clarification: The chilling of milk is done by quick cooling of the raw milk to adequately low temperature. So that the growth of microbes present in milk is inactivated. In chilling process, the temperature of milk should be around 3 – 4°C.
5. What is the temperature of ultra-pasteurization for milk?
a) 125 – 138°C
b) 115 – 120°C
c) 63°C
d) 63 – 65°C
Answer: c
Clarification: Ultra-pasteurization temperature is 125 – 138°C for 2-4 seconds. Sterilization of milk in container is 115 – 120°C for 20-30 minutes. LTLT pasteurization of milk is 63°C for 30 minutes and for thermisation it is 63 – 65°C for 15 seconds.
6. What is bactofugation?
a) Process of removal of microorganisms from milk using centrifugal force
b) Process of removal of yeast and fungi from milk using centrifugal force
c) Process of removal of microorganisms from milk using gravitational force
d) Process of removal of yeast and mold from milk using gravitational force
Answer: a
Clarification: Bactofugation is the process of removal of microorganisms from milk using centrifugal force. It is a special form of separation of microbes, mainly spore formers.
7. Which of the following dryer used to manufacture milk powder?
a) Spray dryer
b) Cabinet tray dryer
c) Pneumatic dryer
d) Fluidized bed dryer
Answer: a
Clarification: Spray dyer is used to produce powder from the solution. It dries the solution stream and separates the solute and evaporates the solvent and forms vapor. The solid particles are collected in a cyclone or drum.
8. What is the temperature of LTLT pasteurization for milk?
a) 125 – 138°C
b) 115 – 120°C
c) 63°C
d) 63 – 65°C
Answer: c
Clarification: Ultra-pasteurization temperature is 125 – 138°C for 2-4 seconds. Sterilization of milk in container is 115 – 120°C for 20-30 minutes. LTLT pasteurization of milk is 63°C for 30 minutes and for thermisation it is 63 – 65°C for 15 seconds.
9. What is skimming efficiency?
a) The amount of fat that can be separated from milk
b) The amount of skim milk that can be separated from whole milk
c) The amount of fat that is added to milk
d) The amount of skim milk that is added to whole milk
Answer: a
Clarification: The amount of fat that can be separated from milk and it depends on the design of the separator, the flow rate of milk and the size distribution of the fat globules.
10. What is the temperature of thermisation for milk?
a) 125 – 138°C
b) 115 – 120°C
c) 63°C
d) 63 – 65°C
Answer: d
Clarification: Ultra-pasteurization temperature is 125 – 138°C for 2-4 seconds. Sterilization of milk in container is 115 – 120°C for 20-30 minutes. LTLT pasteurization of milk is 63°C for 30 minutes and for thermisation it is 63 – 65°C for 15 seconds.