Q&A: Does freezing food kill bugs? And are open mussels at the supermarket safe?

QUESTION: Does freezing food kill bugs?  P. Moon

ANSWER: No. Some microbiologists actually use the freezer to store bacteria. In fact one of the two last remaining samples of the smallpox virus is kept in test tubes in a freezer at the United States Centre for Disease Control and Prevention in Atlanta, Georgia.

My partner contacted a hideous virus from frozen raspberries grown in Chile while she was pregnant with our first daughter. The group most affected by a recent outbreak of E. coli in the US, attributed to frozen chicken quesadillas, were older teenage boys.

READ MORE:
* You can thaw and refreeze meat
* 10 ways to use frozen fruit and veg
* 5 tips for getting the most out of your freezer

Although the instructions on the packet instructed consumers to cook well before serving the quesadillas, it is thought that hungry 17-year-old boys were simply warming the junk food up but not enough to kill the bugs. Microwaves ovens are notorious for heating food unevenly hence you'll often read instructions to move food around the microwave and allow the food to sit to let the heat distribute evenly. So freezing doesn't kill bugs but heat does. Next. 

QUESTION: I was looking at the 'fresh' seafood at our local supermarket and noticed that most of the green-lipped mussels were open. Surely they should be closed.  P. Watson

ANSWER: The mussels are dead.  Green-lipped mussels, or Perna canaliculus, are found locally in New Zealand. Once dead, the adductor muscle no longer holds the mussel closed which is why the defrosted green-lipped mussels were gaping open. Nothing to see here, move on.