Re: softening gelatin.

From: John Cremati <johnjohnc@core.com>
Subject: softening gelatin.
Date: Sun, 16 Nov 2003 17:53:00 -0500

> > This would certainly be more "scientific," measurable and repeatable than
> > pineapple skin. What are these enzymes generally sold for (or is that
> > something I don't want to know?)???
> These are just basic digestive enzymes.. They are very cheap. They
> are probably just ground up pineapple and papaya skins!....

The latex of papaya plant contains proteolytic enzyme (protease)
papain. This enzyme is also found in papaya leaves, fig, pineapple and
some fungi. This enzyme is a popular meat tenderizer for less choice
meats, and it works by partially hydrolyzing elastin and collagen. I
dont think it would tenderize hardened photographic gelatin. The same
for another enzyme ficin.

Another enzyme contained in raw pineapple, bromelain is known to
inhibit gelation of gelatin. When you make fruit jelly, you can't use
fresh pineapple just for this reason. But I don't know if bromelain
would undo the hardened gelatin to increase swelling with or without
any adverse effect.

Since this post is useless photographically anyway, I might add a few
more useless pieces of information.

Papain and other meat tenderizing enzymes are active between 60C and
80C (it doesn't tenderize muscle proteins myosin and actin at room
temperature or refrigeration temperature). This is already a range
for final temperature of cooked stakes. This breakdown of muscle
protein leads to lower the water holding capacity of the meat. So,
such meat tenderizer is most effective with slow, moist cooking method
like braising. This enzyme gets inactive near 100C so stay well below
boiling point, at least for a good part of the cooking. (Better yet is
to buy better cuts.)

There are other protein breaking enzymes. For example, raw wheat germ
contains an enzyme that breaks down gluten. So, if you want to make
germ-rich (how nicely it sounds!) bread, the germ needs to be toasted
before adding to the dough (and you probably want to add some wheat
gluten) to avoid excessively dense bread. Toasting will inactivate the
enzyme so that the gluten is not "cut" by it. Raw wheat germ contains
other enzymes, one of which promotes oxidation of fat in the germ
itself. So raw germ should be kept in freezer.

--
Ryuji Suzuki
"Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)