Minimum amount of pectic enzyme?
Richard Reeves
gram per gallon in fresh juice. While this worked quite well in all
lots, harvested August through November, I'm wondering if anyone is
having good reliable results with smaller doses? I found one comment
in the archives that excessive PE may have some effect on flavor
profile, and in any case would prefer to keep additions at the minimum
required for success on principal. I'm working with high PH (3.8-4.0)
dessert apples that this year will be adjusted to ~3.6 or so with
tartaric acid.
Andrew Lea
I'm not going to answer this directly, but just to set out some
principles which might help in giving a perspective.
The powders of 'pectic enzyme' that you buy are fairly crude fungal
extracts adsorbed on to some sort of inert carrier. The 'activity' will
be tailored by the manufacturer to give an appropriate 'bulk density' -
in your case 1 g per gallon (conveniently one teaspoon per 5 gallons or
20/25L). They contain a number of pectolytic activities principally
pectin methyl esterase (PME) and polygalacturonase (PG) both of which
are required to fully break down pectin. These are enzymes rather than
ingredients, which means that in theory they can go on acting for ever -
or at least that one molecule of enzyme protein can break down many
molecules of pectin. In practice of course other things happen - for
instance in the case of apple the enzymes are deactivated sooner or
later by the 'tannins'.
Pectic enzyme activities are also affected by pH - typically the fungal
enzymes are at their most active at values higher than apple juice,
maybe around pH 4.5 - 5.0. On the other hand as the alcohol level rises
during fermentation, the enzyme proteins are denatured and lose their
activity. Their activity is also highly temperature sensitive - what
might take 24 hours at 20C will only take a couple of hours at 55C. But
much hotter than that and again the enzyme is denatured. Bear in mind
also that typically apples themselves contain PE and yeasts contain PG,
hence many apple juices clear themselves by the end of fermentation.
Adding external enzyme is a kind of insurance, if you require a finished
cider that must be clear.
Not sure I know of any good evidence relating normal use of pectic
enzymes to adverse flavours, but nonetheless the likelihood is that you
can cut down your enzyme usage by half or more and the result will be
much the same - you may have to wait longer, but time is on your side
anyway.
Andrew
--
Wittenham Hill Cider Pages
www.cider.org.uk
Richard Reeves
Isn't it interesting that the confluence of yeast and apple juice (PE
+PG) can equal clarity? The idea is pregnant with metaphor... ; p