Questions from students 20130430a

Answers are under each question

From: MMMMMMMMM
Sent: Tuesday, April 30, 2013 9:15 PM
To: hoishankwan@cuhk.edu.hk
Subject: Questions about FNSC4180 (Food Microbiology)

Dear Prof. Kwan,

I would like ask you several questions about the course, the followings are the

questions:

1. As far as I know, yeasts are responsible for red wine fermentation and lactic

acid bacteria are able to ferment yogurt. Is there any specific organism for the

fermentation of these two food?

A: For "specific organism",  do you mean species? Of course, there are particular species in food fermentation. Red wine fermentation--Saccharomyces cerevisiae. Yougurt--usually lactobacillus bulgarius and Streptococcus thermophilus.

2. From the news I read, I can only recognize H5N1 Influenza related to the dead

turkeys in East Anglia of UK, but I am not able to find out what food-related

microorganism is related to it. What is the food-related microorganism in this

case?

A: Aspergillus flavus--prodced Afla toxin that killed the turkeys.

3. From question 12d in the 2010 pastpaper, "Was the additional canning process

sufficient for the processing of the one-time processed pickled pig knuckle

with wrong pH measurement? Explain."

Does it require the calculation of the resultant number of micro-organisms after

the additional canning process? If yes, do we need to consider the effect of

initial canning process before the additional canning process?

A: Yes. You have to calculate the final number. Of course, you need to consider the initial canning process.

4. From question 12e in the 2010 pastpaper, "Was the technician correct in his

suggestion of the additional remedial processing? If he was wrong, fire him and

suggest new remediation for the canned pig knuckles. Explain."

If I think the answer is incorrect, do I need to suggest an appropriate

additional time? If yes, I am having doubt about whether I need to take the

effect of initial canning process into account because that effect would affect

my determination towards the decimal time required for decreasing the cell

density to an acceptable level.

A: If you think the answer is incorrect, you need to suggest new remediation which may be just not to do anything at all.

I was hoping the above questions could be answered. Thank you very much.

Best Regards,

MMMMMM