# Food Engineering Questions and Answers – Principles of Food Preservation by Canning-4

This set of Food Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Principles of Food Preservation by Canning-4”.

1. The rate of destruction of an organism per minute at any given temperature in a process is the reciprocal of the time in minutes.
a) True
b) False

Explanation: The rate of destruction of an organism per minute at any given temperature in a process is the reciprocal of the time in minutes.

2. For the thermal death time curve, C= minutes to destroy the organism at 121 deg C. Z= slope of thermal death time curve in deg C and T= temperature under consideration and t= time taken to destroy. Then, which of the following represents the lethal rate at T?
a) C
b) T
c) t/C
d) C/t

Explanation: C/t represents the lethal rate at T.

3. For the thermal death time curve, C= minutes to destroy the organism at 121 deg C. Z=slope of thermal death time curve in deg C and T= temperature under consideration and t= time taken to destroy. Which of the following is read from the graphs?
a) C
b) z
c) t/C
d) C/t

Explanation: t/C that is the time taken to destroy the organism at temperature T when C=1 is read from the graph. C and z are known. C/t is then calculated as reciprocal.

4. By plotting the C/t values obtained from a thermal death time curve, a curve is obtained. How is the lethal value obtained from this curve?
a) Area under the curve
b) The center point on the x-axis with respect to beginning and end of curve and then extends to the curve
c) The center point on the x-axis with respect to beginning and end of curve and then extends to the curve
d) None of the mentioned

Explanation: By plotting the C/t values obtained from a thermal death time curve, a curve is obtained. The lethal value is obtained by the area under the curve.

5. Statement 1: In thermal death time curve, after plotting C/t values from it, C value should be equal to Co value.
Statement 2: When Co value versus process time in minutes is plotted on a linear graph paper, a straight line is obtained.
a) True, False
b) True, True
c) False, False
d) False, True

Explanation: In thermal death time curve, after plotting C/t values from it, C value should be equal to Co value. When Co value versus process time in minutes is plotted on a linear graph paper, a straight line is obtained.
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6. With respect to thermal death time curve, D value is the unit defined as the combination of time and temperature to bring about a 90% reduction in spoilage organisms.
a) True
b) False

Explanation: With respect to thermal death time curve, D value is the unit defined as the combination of time and temperature to bring about a 90% reduction in spoilage organisms.

7. Which of the following is required for calculation of process time by Ball’s method?
a) C and z value of thermal death time curve
b) Cold point of the container
c) Number of degrees which exist between the retort temperature and the maximum temperature
d) All of the mentioned

Explanation: All of the mentioned is required for calculation of process time by Ball’s method.

8. Which of the following statements is true?
a) The general method of determining the heat process required for canned food always gives result in terms of total heating time
b) The formula and monogram methods require come-up time
c) Ball has established that 42% of the CUT is reusable in terms of the processing temperature
d) All of the mentioned

Explanation: All of the mentioned is true.

9. When a CUT is 10 minutes and the calculated process was 60 minutes at 116 deg C, then the corrected process time is _____
a) 60 minutes
b) 55 minutes
c) 55.8 minutes
d) 54.2 minutes

Explanation: Ball has established that 42% of the CUT is reusable in terms of the processing temperature. CUT is 10 minutes. Hence 4.2 minutes is deducted. Hence, when a CUT is 10 minutes and the calculated process was 60 minutes at 116 deg C, then the corrected process time is 55.8 minutes.

10. Which of the following factor does safe processing schedule depend upon?
a) Heat resistance of spoilage bacteria
b) Heat penetration characteristics of food in containers
c) Heat resistance of spoilage bacteria & Heat penetration characteristics of food in containers
d) Neither of the mentioned

Explanation: Both of the mentioned are important factors on which safe processing schedule depends upon.

11. For heat penetration considerations for safe processing schedule, the slowest cooling and the fastest heating curves are used to calculate lethal effect of the process.
a) True
b) False

Explanation: For heat penetration considerations for safe processing schedule, the slowest heating and the fastest cooling curves are used to calculate lethal effect of the process.

12. Statement 1: Which of the following methods is used to determine process times for products?
Statement 2: Which of the conditions is the above method used in?
a) Slowest heating-fastest cooling composite data from heat penetration studies will be excess under sanitary conditions
b) Inoculated pack studies, will be inadequate under poor processing conditions
c) Statistical evaluation, will be inadequate under poor processing conditions
d) All of the mentioned, all of the mentioned

Explanation: The entire mentioned are methods used to determine process times for products. All of the mentioned conditions are when these techniques are used.

13. Statement 1: In low and medium acid foods, spore forming organisms are observed.
Statement 2: In acidic products, the organisms must be yeasts, molds etc.
a) True, False
b) True, True
c) False, False
d) False, True

Explanation: In low and medium acid foods, spore forming organisms are observed. In acidic products, the organisms must be yeasts, molds etc.

14. Statement 1: The swelling of cans takes place due to the release of hydrogen gas.
Statement 2: The swelling of cans takes place due to the release of carbon dioxide gas due to molasses and malt extracts.
a) True, False
b) True, True
c) False, False
d) False, True

Explanation: The swelling of cans takes place due to the release of hydrogen gas. The swelling of cans takes place due to the release of carbon dioxide gas due to molasses and malt extracts.

15. Statement 1: Corrosion of cans is more complicated than that of tin and iron alone. Depending on whether the tin forms a complex or not, it acts as the anode or cathode.
Statement 2: In the corrosion process, if hydrogen is not evolved, it exerts a back pressure and opposes further oxidation of iron.
a) True, False
b) True, True
c) False, False
d) False, True

Explanation: Corrosion of cans is more complicated than that of tin and iron alone. Depending on whether the tin forms a complex or not, it acts as the anode or cathode. In the corrosion process, if hydrogen is not evolved, it exerts a back pressure and opposes further oxidation of iron.

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