1. The Del Factor decreases as the initial number of organisms _____________
a) Decreases
b) Increases
c) Remains constant
d) Becomes zero
Explanation: The Del factor decreases as the initial number of viable organisms decreases. This happens because the Del factor is directly proportional to the initial number of viable organisms and is inversely proportional to the viable organisms after the sterilization treatment. That is why it decreases.
2. How long does it take for the autoclave to complete its cycle?
a) 30-35 minutes
b) 50 min to 1 hr
c) 15-20 minutes
d) 10-15 minutes
Explanation: The autoclave completes its cycle within 15-20 minutes at 121°C. An autoclave is similar to a pressure cooker that uses steam to kill the germs. An autoclave can sterilize solids, liquids, etc.
3. The Del factor increases with an increase in the size of the fermenter.
a) true
b) false
Explanation: The Del factor is directly proportional to the number of viable organisms at the start of the sterilization process. Thus, if the size of fermenter increases, the number of starting organisms will also increase and this leads to an increase in the Del factor.
4. Which of the following time is not included in continuous sterilization?
a) Heating time
b) Cooling time
c) Holding time
d) Sterilization time
Explanation: The continuous sterilization includes the time period of heating where the medium is heated, followed by holding time where the medium is held at a certain temperature and finally the cooling period to restore the medium to the fermentation temperature.
5. The holding time at 135°C will be _________
a) 2.44 minutes
b) 51.9 seconds
c) 18.9 seconds
d) 2.7 seconds
Explanation: The Holding time at 135°C will be 51.9 seconds. This temperature time was calculated to give the value of the Del factor. 2.44 minutes was the holding time at 130°C. 2.7 seconds was the holding time at 150°C.
6. Which of the following is a type of continuous sterilizer?
a) Steam Injector
b) Inertial Impaction
c) Electrostatic attraction
d) Interception
Explanation: There are two types of continuous sterilizers- Indirect heat exchanger and Direct Heat exchanger or steam injectors. The inertial impaction, electrostatic attraction, interception are the types of Filter sterilization.
7. What is the function of the holding loop?
a) It heats the medium
b) It sterilizes the medium
c) It holds the medium
d) It cools the medium
Explanation: The function of the holding loop is to sterilize the medium. The heating coil or loop sterilizes the medium and the cooling loop or coil cools the medium to the fermentation temperature. This is the basic process of continuous sterilization.
8. The sterilization in double spiral heat exchanger is done through __________
a) Countercurrent mechanism
b) Counter mechanism
c) Symporter mechanism
d) Antiporter mechanism
Explanation: The sterilization in a double spiral heat exchanger is done through Countercurrent mechanism where steam is passed through one spiral and the medium is passed through the other spiral.
9. Which of the following is the main disadvantage of a direct plate exchanger?
a) Foaming occurs
b) High capital cost
c) If the media contains suspended solids, the plate may get blocked
d) High maintenance
Explanation: The main disadvantage of a direct plate exchanger is that if the media contains suspended solid particles, the plate might get blocked and the medium might not get sterilized. In this case, continuous steam injectors are used which does not get blocked due to suspended solids.
10. The fermenter vessel is sterilized at ____________
a) 20 psi
b) 15 psi
c) 5 psi
d) 10 psi
Explanation: The fermenter vessel is sterilized at 15 psi. The jackets or coils of the fermenter are heated in steam for about 20 minutes. The medium which is sterilized is never added directly to the fermenter vessel until the vessel is sterilized. Otherwise, it may lead to contamination of the medium.