Freezing food

[Alfee]

I know that refreezing food is not paticularly good especially meat or other high risk products. I have always wanted to know the reason behind this. So if anyone has any knowledge of this please let me know!!

[dannydingbat]

Food spoilage is caused by micro-organisms, chemicals, and enzymes. Freezing foods to 0 degrees F. is recommended for best quality.

Freezing stops the growth of microorganisms. However, it does not sterilize foods or destroy the organisms that cause spoilage. A few organisms may die, but once thawed to warmer temperatures, these organisms can quickly multiply. So, once it has thawed out, the refreezing of the food will preserve the higher number of harmful things in it and that is bad news for when you thaw it out (again) and eat it.

[waimarie]

Most text books will tell you that under ideal conditions (warmth & moisture) a single bacterium will divide in two every twenty minutes. Somebody has done the maths and come up with an increase of this single bacterium to 2,097.152 within 7 hours.

The ideal temperature is considered to be blood heat at 37'C. Even so, bacterium will multiply between 10'c-63'C. From this you can see that by thawing a food item the first time it has travelled through this danger zone once. By refreezing it is twice and by thawing again for use it has travelled three times through the danger zone.

I haven't done the multiplication but would suggest it confirms the truth of your opening sentence. You might say a 'gut reaction' in more ways than one.

[nickmo]

Extract from DEFRA site re food hygiene stating bacteria growth as above:
'Bacteria need warmth and moisture to grow. They reproduce by dividing themselves, so one bacterium becomes two and then two become four and so on. In the right conditions one bacterium could become several million in 8 hours and thousands of millions in 12 hours.' the re- freezing of defrosted products is not recommended due to prescence of potentialy harmful bacterias.

Link to storage facts : http://www.eatwell.gov.uk/keepingfoodsafe/storing/

[ann_h]

But you can salvage it once - if you thoroughly cook the defrosted raw meat and thus kill the beasties, you should be OK to freeze it again then.