RENNET.
An indispensable requisite in making cheese is good rennet. Nothing else
will answer the purpose. Different substitutes have from time to time
been tried, but all have met with indifferent success, or absolutely
failed. Acids will produce coagulation, but they spoil the quality of
the cheese. It was once supposed that the gastric juice of the calve's
stomach was acid, and produced coagulation by souring. But it has been
demonstrated that good curd can be produced from sweet new milk, by the
use of rennet, without the development of acid in either the curd or the
whey. How or why the principle obtained by soaking the calve's stomach
produces coagulation has not yet been discovered. What the principle
_is_, is not even known. It appears to be contained in the gastric juice
secreted by the inner membranes of the stomach, and a small quantity of
rennet, stirred into a vat of milk, seems to coagulate it in the same
manner that milk taken into the calve's stomach is coagulated. We all
know the fact that by the use of rennet we can make cheese. Beyond this,
we have little knowledge; so far as we are aware, scientific men are
just as much in the dark as the cheese-maker.
As the stomach of the calf is bifold, we have seen the mistake
frequently made of saving the wrong one. But we presume patrons are
generally well informed on this point now, after so many years'
experience. Where the stomach is not entirely empty, the presence of
curd is a sure guide. Always save the stomach that contains the curd,
and no mistake will be made. If the stomach is empty, save the one that
has a smooth inside surface. The one that has a rough, honey-comb-like
inside surface is worthless for cheese-making, and should, of course, be
rejected.
There are three or four ways of preserving the rennet or stomach, for
future use. Only two, we believe, are generally practiced in America. In
all cases, the rennet is to be turned wrong side out, all its contents
being thrown away, and the inner surface carefully cleaned by picking
off all hairs and bits of grass, hay or other substance which the calf
may have taken into its stomach. But the rennet should never be washed,
and great care should be taken not to remove any of the inner membrane
of the rennet, as in this membrane resides all its strength. Washing
would rinse out the gastric juice, and weaken the rennet; and much
washing would render it nearly or quite worthless.
When properly cleaned, the rennet should be thoroughly rubbed with salt,
outside and in, turned the right side out, stretched on a crotched stick
or on a hoop, and hung up in a cool, dry place, to cure. In private
dairies, the farmer's wife, after salting the rennet, sometimes spreads
it on an earthen plate and sets it away to dry, frequently turning it on
the plate. Rennets dried in this way are nice, but it is too much work
to tend to them for a general adoption of this method of drying. Drying
on a stick or a hoop is the common way, and answers the purpose very
well. The only trouble is to find a place both dry and cool. It is
generally conceded, we believe, that heat injures the strength of the
rennet. Hence the importance of curing it in a cool place. Freezing is
thought by many to add to or develop the strength of the rennet. Be this
as it may, old rennets, that have hang up in the dry-house or some
other convenient place through the winter, will go much further in
cheese-making than new rennets.
Another method of preserving rennets is by packing them into salt. This
is quite common, and is practiced by some of our best factories. It is
less troublesome than drying them, and is a sure preventive against
moths, which are apt to get into dried rennets. By salting them down,
there is less trouble to find a cool place in which to keep them during
the summer. But care should be taken to use only the purest salt in
packing rennets. Salt not fit to salt curd with is not fit to pack
rennets in, for when the rennets are used, the salt will be in the
liquid and find its way into the mass of curd. Besides, pure salt is
much the better preservative, and will keep either meat or rennets
sweeter than impure salt.
Some think rennets preserved in this way are not as strong as those that
are dried. We do not quite see the philosophy of this, since by packing
in salt, none of the virtues of the rennet can escape by evaporation,
and must be retained either in the rennet or in the salt. It may be said
that the salt injures the strength of the rennet. If so, why does it not
prove equally injurious when the rennet is dried? In both methods of
preserving, salt is freely used--generally all that the rennet will
absorb. A batch of dried rennets may go farther than the same number
packed in salt, and _vice versa_; but this does not prove that the
_same_ rennets would not have equal virtues preserved by either method.
The German method of preserving rennets is by blowing them up like a
bladder, and drying them. This is the way in which the Bavarian rennets,
which reach this country, are preserved. We believe no salt is used.
The method is simple, and if it answers the purpose equally well, we see
not why it may not be adopted in this country. We understand that the
Bavarian rennets give very good satisfaction. But, as we have never used
them, nor seen them used, we cannot speak from positive knowledge.
Veal rennets are generally supposed to be better than deacon rennets.
Certain it is that the stomach of a calf that never sucked the cow is
not worth much in cheese-making. It is both small and weak. It seems to
be necessary that the process of digestion should go on for a while, at
least, that all the functions of the animal may become active and a full
secretion of gastric juice take place. Some are of the opinion that the
rennet is best when the calf is from three to five days old, as at that
age it is not likely to have taken anything but milk into its stomach,
which is best prepared for digesting that kind of food, the first
process of which is coagulation. Veal calves are apt to get hold of
other food, and the stomach is therefore less exclusively adapted to a
milk diet. Hence, it is argued, if the veal rennet is better than the
deacon, the stomach of the cow or ox ought to be better than that of the
veal calf. Whatever may be the conclusion, we have, and shall probably
continue to have, both deacon and veal rennets, both kinds of which have
been found to work satisfactorily.
Much seems to depend on the condition of the calf when killed. If it
goes too long without food, the stomach gets inflamed and is not only
deprived of its strength, but is partially diseased, and, therefore,
unfit for cheese-making. This is the condition of most of the rennets
taken from calves killed in our larger cities, the calves going without
food sometimes two or three days. On the other hand, when the calf has a
full stomach, the juices seem to be absorbed in the food, and the rennet
is, therefore, weak. The best time for killing the calf appears to be
just after the stomach has emptied itself, when the appetite of the calf
begins to be sharp and the secretions of gastric juice are copious. This
will generally be found from twelve to eighteen hours after eating. If
fed at night, it may be killed any time the next forenoon.