Naked Science Forum

Life Sciences => Cells, Microbes & Viruses => Topic started by: CZARCAR on 11/10/2011 13:35:02

Title: ?bacteria destruction by freezing?
Post by: CZARCAR on 11/10/2011 13:35:02

listeria news has tv saying to wash even bananas! Will freezing destroy listeria & other bacterium?

Title: ?bacteria destruction by freezing?
Post by: CliffordK on 11/10/2011 14:24:27

According to Wikipedia (http://en.wikipedia.org/wiki/Listeria#Epidemiology), Ice Cream is sometimes associated with Listeria. 

You do wash your ice cream, don't you?

Actually, it appears to be soft-serve ice cream, as one might find in some chain restaurants such as Dairy Queen, so it may be contaminated equipment, and not the frozen food.

Likewise, there was a study once that ice machines may harbor more bacteria than some public restrooms (with lots of disinfectant).

I did a search for Listeria Freezing (http://www.google.com/search?q=Listeria+Freezing).  I am getting a bunch of abstracts.  It seems to indicate that freezing will reduce the Listeria counts, but does not eliminate the pathogens, even after extended periods of freezing.

Here is a CDC summary on Google Books (http://books.google.com/books?id=NZsS6tbSAFYC&pg=PA163&lpg=PA164&ots=3sGGbhZiS6&dq=Listeria+Freezing#v=onepage&q=Listeria%20Freezing&f=false) that seems to have some good information about freeze/thaw cycles.  See the section that starts at the bottom of page 163.

Title: ?bacteria destruction by freezing?
Post by: Bored chemist on 11/10/2011 18:59:35

Freezing (strictly speaking thawing) will definitely ruin the bananas.

Title: ?bacteria destruction by freezing?
Post by: CZARCAR on 11/10/2011 19:31:58

Quote from: Bored chemist on 11/10/2011 18:59:35

Freezing (strictly speaking thawing) will definitely ruin the bananas.

wrong!= try discounted banas already brown & freeze & they get browner, then from freezer to microwave for however long [1.5 min here] & maybe rotate halfway. Cut the bana tip off & squeeze out like toothpaste- mix with dry milk, fruit juice, or? Like a pudding, it holds its proof.
Thanx CK, I shudda asked about freezing methods to freeze rupture bacteria. Seems a bacteria has enuff water in it so freeze expansion would kill it,dunno, maybe weted so at least I can run up my fridge defrost bill?