In article ,
J Jackson wrote:
Stephen Williams wrote:

: One other tip you may wish to use is to cap the Jelly with a wax coating
: after it has set in the Jar.

I beg to differ. pour the very hot jelly into heated jars and screw down
the lids firmly immediately to make an air tight seal. As the they cool
down, the lids should "pop" as a vacuum forms inside. Thus treated they
should keep for years - literally.

Not surprising, considering that even such jelly keeps for years open
to the air!

I'm baffled by this allowing to cool in the open and then waxing business.
Invariably there is contamination and the jam/jelly is less likely to keep
very long.

Not really. I agree that it should be done when the jelly is still hot
if done at all, but it isn't necessary anyway.

Only thing I can think of is that it is advice from the period before
glass jars and air tight tops were available. Also I suppose they look
pretty in glossy photos in coffe table preserve books.

Well, yes :-)


The reason that some jams, jellies etc. don't keep very long is that
they have a low concentration of sugar and acid. In particular, many
commercial ones use a high amount of (probably synthetic) pectin,
which is a protein. Combine that with a small proportion of sugar
and acid to water, and you have a recipe for decay. If the preserve
doesn't have enough free water to allow bacterial and fungal growth,
it will keep indefinitely, and a high acid level blocks most bacteria
and some fungi.

Because of this, the normal problem with home-made acid fruit preserves
is mould on the surface, and that can just be scraped off. If they are
low on sugar, they may ferment (acetobacter, saccharomyces or lactobacter
are the main ones). The last makes things smell like sick, but none
will harm you.

I regularly eat jams and jellies over 5 years old, and have eaten ones
over 10 years old. This Christmas, we ate japonica cheese that had been
open to the air since October 2001. It was excellent. But the key to
all of them is high acid and not low sugar.


Regards,
Nick Maclaren.