Microbiology PRE- ASSESSMENT

Paper , Order, or Assignment Requirements

MICROBIAL SPOILAGE OF CANNED FOOD  – PRE-PRACTICAL ASSESSMENT

 

Questions to answer and hand to your demonstrator at the start of week 2 of the can prac class i.e. week 4 of the semester on August 11:

 

  1. In relationship to Clostridium botulinum spores, what is meant by a 12D heat process?

 

  1. What types or groups of microorganisms would you expect to find if a can has been under-processed. Explain the reason for your answer.

 

  1. What is the meaning of leaker spoilage of canned food and how does this occur?

 

 

  1. What types of microorganisms would you expect to isolate from a can if there is leaker spoilage?

 

  1. Suggest two sources of organisms that may contribute to leaker spoilage

 

  1. What physical tests would you do on the can seam integrity to determine if the can spoilage has been caused by leaker spoilage?

 

  1. Controls need to be applied to ensure production of a batch of appertised food  (in a glass bottle, can or sealed pouch) is shelf stable and safe for consumption. As a brief summary, control of the following seven (7)  steps is important to ensure production of appertised (commercialy sterile) shelf-stable cans.
  2. Supply of cans from the can manufacturer
  3. Source, supply and storage of the raw materials
  4. Preparation of the product going into the can
  5. Applying the lids
  6. Retorting the cans
  7. Cooling the cans
  8. Storage and distribution of the cans

 

  1. Of the steps listed above, state four (4) steps that are the most important to prevent leaker spoilage in a batch of processed cans.  Explain why you have chosen each of them.

 

i.

 

ii.

 

 

iii

 

iv.

 

 

  1. Of the steps listed above, state three steps that are the most important in controlling unerprocessing, in a batch of processed cans. Explain why you have chosen each of them.

 

i.

 

ii.

iii

 

  1. Why is Liver broth (covered with a layer of 2% agar ) commonly used as a growth medium, when analysing cans to check for sterility or cause of spoilage?

 

  1. Why is Dextrose Tryptone Broth commonly used as a growth medium, when analysing cans to check for sterility or cause of spoilage?

 

  1. After inoculation of the food into the above media the tubes are incubate at two temperatures i.e. 300C and 550C. Why are both of these temperatures used?