I read in one post ("Do I need to boil filled jam/chutney jars? [duplicate]"

"....So, initial sterilization is always required to clean the jars themselves. The second boil pasteurizes the contents...."

My question in very simple:

In the case of cooking to boiling temperature jam, does the hot jam not desinfect the jar?

What additional value does (in this case) does disinfection add?

1 Answer 1


Many people certainly think so; it's a common preparation technique. By policy, here on SA, we need to answer you with the advice of the relevant healthcare authorities, which is: no, it is not adequate, particularly if your post-fill processing time is less than 10 minutes.

Here's their reasoning: one of the things you're trying to eliminate is not just bacteria, but bacterial spores, some of which can survive several minutes at boiling temperatures. While dumping boiling jam into a jar does kill any live bacteria, it isn't hot enough for long enough to kill all spores, and if you're doing boiling jam you're probably only putting it in a hot water bath for a couple of minutes (if at all). It also matters whether the jars are new or are being re-used, and how recently they were washed.

Canning foods is a game of risks, and you decide which risks you (and your friends and family) can tolerate.


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