Bacteria in Chicken stock
- gcwells Jan 5, 2007 05:10 PM
Does anyone know the temperature one needs to cook chicken stock at in order to kill the bacteria?
I think it is a time at a temperature rather than a specific temperature. I've always seen the following: bring to a rolling boil, reduce to a simmer, simmer 10-15 minutes.
re: Karl S
Karl is correct.
From Bone Appetit by Robert L. Wolke
"...according to my correspondents, among them a food safety consultant and a biochemist at the National Institutes of Health. It seems that all bacteria are not necessarily killed at 212 degrees Fahrenheit. Some of them can survive by forming highly invulnerable spores.
...A common pathogenic -- disease-causing -- genus of spore-forming bacteria found in soil, water and the intestinal tracts of humans and animals is Clostridium, especially the species C. perfringens, which is a major cause of food poisoning, and the much rarer C. botulinum, which produces botulin toxin, one of the most potent poisons known. Clostridium bacteria don't need oxygen to live; in fact they can't survive in air, so the interior of a pot of stock is a perfect growth medium.
To kill these spores, temperatures higher than 212 degrees are needed. That's why medical and surgical equipment is sterilized in an autoclave, a sort of pressure cooker."
In other words, in order to kill all the bacteria in stock, you will require a pressure cooker or an autoclave. Boiling stock helps to kill quite a few organisms but not all. What will go a long way in keeping it safe is cooling it quickly (smaller containers and/or ice bath) and using it in a day or two or freezing it. What may not be a good idea, though, is the commonly held thought that stock can be kept indefinitely in the fridge as long as it's boiled every few days. That practice, imo, is risky business.
GCWELLS, I just read a fascinating chapter in Bruce Cost's "Guide To Asian Ingredients". When families in China poach a chicken, they save the stock for poaching the next chicken. Some families have a "master stock" they use that has been replenished, used weekly and in the family over a 100 years.
I have always considered it standard practice to bring any frozen or refrigerated stocks to a full rolling boil for 5 minutes before using.
Yeah, and boiling any stock reduces it a bit and intensifies the flavor.
The exception being Campbell's Soup. :)