This set of Food Engineering Multiple Choice Questions & Answers (MCQs) focuses on ” Principles of Food Preservation by Canning-3″.
1. Statement 1: Longer heating time is required to kill spores as the concentration of sugar increases.
Statement 2: Sugar helps in the preservation of food whereas salt does not.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: Longer heating time is required to kill spores as the concentration of sugar increases. Both sugar and salt help in preserving food.
2. If fats and oils prevent bacteria spore formation and help in pore formation, why is it difficult to kill yeast in a salad dressing?
a) Because the bacteria get stuck in the oil phase
b) This statement is incorrect
c) It is relative with respect to waster and hence better preserver
d) None of the mentioned
View Answer
Explanation: It difficult to kill yeast in a salad dressing because the bacteria get stuck in the oil phase.
3. Which of the following statements with respect to activation energy are true/is true?
a) With every 10 deg C increase in temperature, the velocity of the substrate-enzyme reaction doubles
b) With the increase in temperature, the enzyme itself gets destroyed as it is proteinous and the rate decreases
c) The optimal temperature for the carrying of the substrate-enzyme reaction is when the coefficient of the ratio at increased temperature ( by 10 deg C) to the present temperature is 1
d) All of the mentioned
View Answer
Explanation: All of the mentioned statements with respect to activation energy are true.
4. Statement 1: With the increase in temperature, the enzyme gets deactivated.
Statement 2: With the increase in temperature, the enzyme gets reactivated.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: Both the statements are true. This is because some enzymes like peroxide get reactivated after heating.
5. Reeti subjected all of these enzyme based food items to heat. Which among these did not get deteriorated?
a) Pickle with vinegar
b) Pickle without vinegar
c) Pear
d) Tomato with slight salt
View Answer
Explanation: All of the mentioned food items have enzyme peroxide in them. Vinegar added to pickles increases the heat destruction of peroxide. Hence the enzyme gets killed and no biological activity is present. As a result it does not get deteriorated. Whereas in the other cases, sugar in pears and salt in tomato resists heat and protects peroxide.
6. Statement 1: Destruction of the phosphate based enzyme in milk after heat treatment is an indication that several pathogens have been destroyed.
Statement 2: Destruction of the peroxide based enzyme in fruits after heat treatment is an indication that several pathogens have been destroyed.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: Destruction of the phosphate based enzyme in milk after heat treatment is an indication that several pathogens have been destroyed. Destruction of the peroxide based enzyme in fruits after heat treatment is an indication that several pathogens have been destroyed.
7. Statement 1: Sterilization value of steam depends largely on the transfer of heat of vaporization to the object upon which it condenses.
Statement 2: Canned food items which heat up by convection heat up faster than those by conduction.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: Sterilization value of steam depends largely on the transfer of heat of vaporization to the object upon which it condenses. Canned food items which heat up by convection heat up faster than those by conduction. This is because heat transfer by convection (actual movement of molecules) is faster than heat transfer by conduction (simple molecular vibration).
8. Which of the following food items is the lowest in heating up?
a) Broths and thin soup with negligible starch in it
b) Fruits packed in water/syrup with large pieces
c) Evaporated milk
d) Chopped vegetables with high starch content packed with free liquid
View Answer
Explanation: Broths and thin soup with loads of starch in it. The starch in these solids which separates or leaches out retards heat. Hence, in chopped vegetables with high starch content packed with free liquid, the leached starch retards heat transfer.
9. Which of the following comes under the categories of food – broken curve heating food?
a) Evaporated milk
b) Fruits packed without water/syrup
c) Syrup packed with sweet potatoes
d) All of the mentioned
View Answer
Explanation: In syrup packed with sweet potatoes, the heat transfer is through convection initially. But when the starch particles from the solids separate, they retard the heat transfer.
10. Statement 1: In a thermocouple, two wires are of different materials and a voltage difference is created due to the conduction of each material at the juncture and this gives us the difference in temperature in both metals and hence the temperature of the liquid.
Statement 2: The zone of slowest heating in a container is called cold point of a container.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: In a thermocouple, two wires are of different materials and a voltage difference is created due to the conduction of each material at the juncture and this gives us the difference in temperature in both metals and hence the temperature of the liquid. All points inside a container do not heat up at steady rates. The zone of slowest heating in a container is called a cold point of a container.
11. Statement 1: The cold point of a food item getting heated up by convection has its cold point at the centre of the container on the vertical axis.
Statement 2: The cold point of a food item getting heated up by conduction has its cold point at the bottom of the container on the vertical axis.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: The cold point of a food item getting heated up by convection has its cold point at the bottom of the container on the vertical axis. The cold point of a food item getting heated up by convection has its cold point at the center of the container on the vertical axis.
12. For canning technology, the cold point of the can is determined by soldering stuffing boxes and different depths in different boxes, a thermocouple in each box and a potentiometer in each box.
a) True
b) False
View Answer
Explanation: For canning technology, the cold point of the can is determined by soldering stuffing boxes and different depths in different boxes, a thermocouple in each box and a potentiometer in each box.
13. Which of the following parameter is important to know and to plot the heating and cooling curves?
a) fh
b) fc
c) Initial temperature (IT) and retort temperature(RT)
d) All of the mentioned
View Answer
Explanation: All of the mentioned parameters are important to know and to plot the heating and cooling curves.
14. The period of time elapsed from placing the cans into the retort and starting to heat until the retort reaches processing temperature is termed as _____
a) Slope of cooling curve, fc
b) Slope of heating curve, fh
c) Zero time
d) Come-up-time
View Answer
Explanation: The period of time elapsed from placing the cans into the retort and starting to heat until the retort reaches processing temperature is termed as Come-up-time.
15. Statement 1: The time required in minutes for a heating/cooling curve to traverse one log cycle is represented by its slope and denoted as fh and fc respectively.
Statement 2: The time when heating started is called the zero time.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: The time required in minutes for a heating/cooling curve to traverse one log cycle is represented by its slope and denoted as fh and fc respectively. The time when the retort reached processing temperature is called the zero time.
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