It is usually understood that rennets are calves' stomachs salted and
dried, or otherwise prepared; but it is not so certain that all the
rennets in market are of this kind. The stomachs of the young of all
milk-eating animals may be used for curding milk. We are not so sure
but that among "Bavarian" rennets we get the stomachs of the young
of every animal known under the sun. They are of all sizes and all
degrees of strength, but are generally liked by those who use them.
They are cured by tying the two ends, and blowing the rennets up, like
bladders. A better way, we think, is to rub them well with pure dairy
salt, stretch them on a hoop or crotched stick, and hang them in a cool
dry place. Some simply fill them with salt, tie them, and hang them up
to dry. A great objection to this is, that the salt is likely to draw
moisture from the atmosphere, and in wet weather the rennets are liable
to drip and thus lose strength. Salting rennets down in a barrel, as we
do meat, is considered objectionable--for what reason, we know not. The
writer had excellent "luck," one season, with rennets preserved in this
way. In whatever way preserved, rennets should, by all means, be kept
cool. Heat is found to be very injurious, while cold--even freezing
and thawing--appears advantageous. Possibly because the freezing and
thawing loosen the fiber and set the rennet spores free.