This set of Microbiology Multiple Choice Questions & Answers (MCQs) focuses on “Preservation of Foods”.
1. The temperatures used for canning foods ranges from ____________________
a) 0-20 degree C
b) 20-60 degree C
c) 60-100 degree C
d) 100-121 degree C
View Answer
Explanation: The temperatures used for canning foods ranging from 100 degrees C for high-acid foods to 121 degrees C for low-acid foods.
2. In the high-temperature short-time (HTST) method of pasteurization, milk is exposed to a temperature of _________
a) 132 degree F
b) 145 degree F
c) 161 degree F
d) 120 degree F
View Answer
Explanation: The HTST process employs equipment capable of exposing milk to a temperature of 161 degrees F (71.7 degrees C) for 15 secs.
3. Sterilization occurs at high temperatures for long periods of time.
a) True
b) False
View Answer
Explanation: Sterilization exposes milk to ultrahigh temperatures for very short periods of time, for example, 300 degrees F (148.9 degrees C) for 1 to 2 seconds.
4. Which of the following microorganism survive at -9 to -17 degree C?
a) Salmonella
b) Staphylococci
c) Bacilli
d) Clostridium
View Answer
Explanation: Species of Salmonella survive for longer periods of time at -9 to -17 degree C which is unlike the situation in which microbial count of most frozen foods decreases during storage.
5. Which of the following microorganism is eliminated in canned foods?
a) Mycobacterium tuberculosis
b) Coxiella burnetii
c) Clostridium botulinum
d) Lactobacillus
View Answer
Explanation: The most important organism to be eliminated in canned foods is the spore forming anaerobe Clostridium botulinum, which is capable of producing a very potent lethal toxin.
6. Phosphatase enzyme present in milk is destroyed in which of the following processes?
a) Sterilization
b) Canning
c) Dehydration
d) Pasteurization
View Answer
Explanation: Phosphatase is an enzyme present in raw milk and in many tissues which are destroyed by adequate pasteurization.
7. Jellies and jams are rarely affected by bacterial action.
a) True
b) False
View Answer
Explanation: Jellies and jams are rarely affected by bacterial action because of high sugar content. However it is uncommon to find mold growth on the surface of jelly which has been exposed to air.
8. Which chemical is used to inhibit mold growth in bread?
a) benzoic acid
b) nitrates
c) sorbic acid
d) lactic acid
View Answer
Explanation: Sorbic acid and propionic acid are used to inhibit mold growth in bread. They are organic in nature.
9. Acetic acid and lactic acid are used for __________________
a) curing meats
b) preservation of color
c) preservation of pickles
d) inhibiting mold growth
View Answer
Explanation: Foods prepared from fermentation processes,e.g., sauerkraut, pickles, and silage for animals are preserved mainly by acetic, lactic and propionic acids produced during the microbial fermentation.
10. Which of the following method is used for treatment of water used for the depuration of shellfish?
a) Chemicals
b) Radiation
c) Low temperature
d) Osmotic pressure
View Answer
Explanation: Radiations are used in the food industry, control of surface growth on bakery products, sanitation of equipment and treatment of water used for the depuration (cleansing) of shellfish.
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