If one must prepare his own rennet, the better way is to do it in a
lump before the cheese-making season begins. Get a strong barrel and a
pounder--such as used by washerwomen; also a wringer. Take old rennets
and cut them into strips. Make a weak brine of pure water, by using
one pound of salt to twenty pounds of water, and in this, soak, pound
and wring your rennets. Hang them up and freeze them; then soak, pound
and wring them again; and so on as long as you can get any strength.
When done, carefully settle, skim, and strain your liquid. Put it in a
clean barrel or stone jars, put in all the salt that it will dissolve,
so that a little will settle on the bottom, then stop or cover tight;
put in a cool place and take from it as wanted for use. There is
nothing better than saturated brine for keeping animal products. Be
sure, however, that you use only the purest dairy salt in preparing
brine. Some say that only stone jars should be used for keeping rennet.
We have used an ash tub for the amount prepared weekly. To keep the
wood from tainting, we invariably, every time we dipped out rennet and
exposed new surface, rubbed it with salt.