This set of Fruits Processing Multiple Choice Questions & Answers (MCQs) focuses on “Conventional Thermal Processing and Preservation”.
1. What is the purpose of thermal processing?
a) To destroy microbial activity
b) To boil the product
c) To thaw the frozen products
d) To destroy the Vitamin B12
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Explanation: The basic purpose for the thermal processing of foods is to reduce or destroy microbial activity. It also reduces or destroys the enzyme activity. It also helps in producing physical or chemical changes to make the food meet a certain quality standard.
2. What are the different thermal processes?
a) Isothermal, adiabatic
b) Isothermal, isobaric
c) Adiabatic, isobaric
d) Isothermal, adiabatic, isobaric
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Explanation: There are several types of thermodynamic processes. Isothermal is a process where the system’s temperature is constant. The adiabatic is process where no heat is exchanged by the system. The isobaric is a process where the system’s pressure is constant.
3. Which of the following factors that affect thermal processing?
a) Temperature
b) Pressure
c) Moisture content
d) Water activity
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Explanation: Thermal processing is defined as the combination of temperature and time. It is required to eliminate a desired number of microorganisms from a food product. It is one of the oldest methods of preservation. Various temperature and time combination are used for different products for satisfactory results.
4. What is the sterilization temperature in autoclave?
a) 121°C
b) 100°C
c) 180°C
d) 150°C
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Explanation: The standard temperature for an autoclave is 121°C. The temperature of boiling water is 100°C. This is not sufficient to sterilize the autoclave because bacterial spores can survive in this temperature. The bacterial spores can regenerate under suitable conditions.
5. Which of the following can be sterilized using dry heat oven?
a) Powders
b) Juices
c) Jellies
d) Pulp
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Explanation: Dry heat ovens are used to sterilize items that might be damaged by moist heat. Examples such as powders, petroleum products, sharp instruments. The heat is absorbed by the outside surface of the item, and then passes towards the center of the item layer by layer.
6. What temperature will kill mold?
a) 160-171°C
b) 6-7°C
c) 60-71°C
d) 85-95°C
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Explanation: Heat-sensitive organisms like yeasts and molds are destroyed by heat treatments at 60-71°C. Some types of molds produce spores which are heat-resistant. These spores can survive heat treatments in pickled vegetable products. But molds require oxygen for growth and cannot survive anaerobic conditions.
7. How does dry heat kill bacteria?
a) By destructive oxidation method
b) By oxidation reduction method
c) By destructive reduction method
d) By reduction method
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Explanation: The destructive oxidation method is the dry heat that helps to kill the microbes. This destroys big biological compounds like proteins. The vital cell components are damaged and the finally the microbe dies.
8. Which of the following category is microwaving method?
a) Moist heat method
b) Dry heat method
c) Dry and moist heat method
d) No heating method
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Explanation: Microwaving is considered to be a moist heat method. It is partially relies on the effects of steam. Microwaves enter the food and cook from the outside in. It also uses the radiations for heating the product. The radiation heats the molecules and thus disrupting the structure of water bonds.
9. What is use of wet cooking method?
a) Softens tough fibers
b) Carbohydrate metabolism
c) Prevent protein denaturation
d) Carbohydrate metabolism and prevent protein denaturation
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Explanation: Cooking with wet heat is a process where food is cooked by being placed into a hot liquid or exposed to steam. Wet cooking methods are excellent at softening tough fibers in foods. The water or the steam used should be hygienic and clean.
10. Is steaming a wet cooking method?
a) True
b) False
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Explanation: Steaming is a moist-heat method of cooking. It works by boiling water which vaporizes into steam. It is the steam that carries heat to the food. Unlike boiling food submerged in water, with the food is kept separate from the boiling water but comes into direct contact with the hot steam.
11. What is Z value in autoclave?
a) Temperature coefficient of microbial destruction
b) Pressure coefficient of microbial destruction
c) Time coefficient of microbial destruction
d) Relative humidity coefficient of microbial destruction
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Explanation: The z-value can be used for determining the temperature coefficient of the microbial annihilation. It also studies the resistance of microbe to variable temperature. The study also shows that the number of degrees of temperature that can produce a 10-fold variation in the sterilization rate is called as z- value.
12. What is the thermal death time for most organisms?
a) 20 minutes
b) 30 minutes
c) 40 minutes
d) 10 minutes
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Explanation: The thermal death point (TDP) of a microorganism is the lowest temperature at which all microbes are killed in a 10-minute exposure. Different microorganisms will respond differently to high temperatures. The combination of temperature and time plays an important role in destroying the microbes.
13. What is the thermal death point of E coli?
a) 80°C at 20 minutes
b) 80°C at 30 minutes
c) 80°C at 40 minutes
d) 80°C at 10 minutes
View Answer
Explanation: The lowest temperature at which all microbes are killed is called as thermal death point. With the moist heat, bacteria E. coli are killed at 80°C at 10 minutes which is known as the thermal depth point. The thermal processing techniques are required to control the quality of foods with respect to microbial activity.
Sanfoundry Global Education & Learning Series – Fruits Processing.
To practice all areas of Fruits Processing, here is complete set of 1000+ Multiple Choice Questions and Answers.
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