Bacterial Contamination of Frozen Foods

[bripen]

Steve,
I didn't want to hijack the other thread any more than I already had. In answer to your question about my reference to Vibrio in frozen foods, I found that in the Oct/Nov 2006 Issue of Coral Magazine, Vol. 3 No. 5 Pg. 82 The samples of food found with the Vibrio were specifically mentioned to have come from the USA, but they did not mention name brands. They did, however, test foreign and domestic brands in their study, and they also mention another study done. Good info worth tracking down, as not only was Vibrio found, but numerous other pathogenic bacteria.

 

[NaH2O]

Wow! Great thread. Tagging along on this....

I would have figured long freezing of the foods would kill off pathogens. I guess it isn't a deep enough freeze? With regards to the bacteria.....I wonder what kind of thawing process they did before they tested for bacteria. I haven't seen the article, so I'm not sure if it mentions the process they used.

 

[bripen]

Wow! Great thread. Tagging along on this....

I would have figured long freezing of the foods would kill off pathogens. I guess it isn't a deep enough freeze? With regards to the bacteria.....I wonder what kind of thawing process they did before they tested for bacteria. I haven't seen the article, so I'm not sure if it mentions the process they used.

1 gram samples were diluted with 1 ml of sterile saline solution, then spread on Agar plates. Interestingly, where bacteria colonies were "always found in the melted liquid portion of the samples, never in the food organisms themselves. This suggests that the germ load in frozen food is concentrated in the melted water."
That's why I was asking about rinsing frozen foods, and if anyone knew of an easy method to drain/strain them without a lot of loss?

 

[steve-s]

I would have figured long freezing of the foods would kill off pathogens. I guess it isn't a deep enough freeze?

Freezing actually preserves bacteria, it will not kill it. With some it just slows it down. High heat and rapid shifts in pH are the best means of destruction.

1 gram samples were diluted with 1 ml of sterile saline solution, then spread on Agar plates. Interestingly, where bacteria colonies were "always found in the melted liquid portion of the samples, never in the food organisms themselves. This suggests that the germ load in frozen food is concentrated in the melted water."
That's why I was asking about rinsing frozen foods, and if anyone knew of an easy method to drain/strain them without a lot of loss?

I would really like to see how that study was carried out. The results make no sense

 

[NaH2O]

Thanks Steve. I wasn't even thinking....when I read your response I thought, "DUH". Ugh....it's been too long since University days. I can tell you how quickly it takes to heat up Chicken Nuggets in the microwave though :lol:.

 

[leebca]

I read that article the other day. I think it poses more questions than answers.

The procedure used to find the bacteria initially was not in keeping with sound microbiological techniques. The German lab findings were not duplicated by all labs. The identification of the bacterial species seems to be a moot point, not having corroboration.

However, the manufacturer of several frozen foods claims the food is sterilized or microbe-free. No mention is made of the liquid media. Finding bacteria 'on' or 'in the broth' of frozen foods would be normal. "Bacteria-free" frozen food is a nice thought, but not very practical and hard to attain for frozen foods in this hobby. "Disease-free" would be more likely, providing there's a list of the pathogens the food is actually free of, or pathogen groups not found in the food. No manufacturer wants to go that far -- like manufacturers of products also prefer to stop at "reef safe" when they really haven't tested against all reef marine livestock, rather than list what they know.

I'm afraid that the hobby is full of half-truths and mis-representation enough to assume the aquarist is not getting when he/she thinks they are getting in the way of foods. Just look at prepared food ingredients compared to the sales/marketing claims and you can see a disconnect fairly easily.

So what/who can be believed? :evil:

 

[Slickdonkey]

So I take it that just like "human food", if I leave my frozen cubes out on the counter one night I should just throw them away rather than refreeze them?

 

[leebca]

Yes. As well as those that are 'freezer burned,' thawed in transit to your home, and may have thawed getting to or at the place you bought them from.

Look for signs of previous thawing by 'juice' on the wrapper. :evil: