While success in using a cooker is reasonably sure if directions are
clear and detailed, and can be followed exactly, yet it is well to
understand, in a general way, the conditions of success in order that a
deviation from directions, if such should ever be found necessary, will
not mean failure.
As the cooking depends upon the retention of heat, it stands to reason
that there must be heat to retain. A pint of food does not contain as
much heat as a quart, even though both be of the same temperature to
begin with. This can be demonstrated by setting a pint and a quart of
boiling water side by side. The pint will lose its small amount of heat
and grow cold much sooner than the quart, with its larger amount. After
an equal time eight quarts of food in the cooker have been found to
register 15 degrees Fahrenheit higher than one and one-half quarts,
other conditions being the same. This explains the failures of some
beginners which are due to the fact that such a small quantity of food
was taken that there was not sufficient heat to begin with. Obviously
this danger is less with foods requiring only a slight cooking, since,
even with small quantities, some time elapses before the food grows too
cold to cook at all.
The _total quantity of food_ is, therefore, seen to be an important
factor in success. The larger the amount of food, the higher the
temperature will be at the end of a given length of time. Where the
amount is very large, as in the case of hotel and institution cookery,
this gain is so great that the time required for cooking is materially
reduced.
_The proportion between the amount of food and the size of the utensil_
in which it is cooked is equally important. Experiments have shown that
one and one-half quarts of water, in a pail just large enough to hold
it, will register 15 degrees Fahrenheit more than the same measure of
water in a nine-quart pail at the end of an hour; while at the end of
twelve hours there is 28 degrees of difference. It is thus seen that a
well-filled kettle is more likely to cook successfully than one
partially filled. When it is impossible to cook in a smaller pail, and
thus avoid vacant space in the kettle, the difficulty may, to some
extent, be offset by using a pan for the food with sloping sides and
broad rim, such as a “pudding pan,” which may be set into the
cooker-pail and, by resting upon its rim, will be suspended in it. This
arrangement admits of filling the lower part of the pail with boiling
water or with boiling food, in case a second kind of food is to be
cooked for the same length of time.
_Space between the pail and packing material_ is also likely to be
disastrous, so that it is not advisable to try to use a small pail in a
“nest” made for a large one without the “space adjuster” described on
page 22. Even the space which results after a short use of a newly
packed box will be sufficient for the escape of some heat and should
always be filled in.
_Place the cooker near the stove_, since it is important to transfer the
food very quickly from one to the other. The cooker should be open, the
cushion removed and everything in readiness before the food is taken
from the fire; then, before it has time to stop boiling, it should be in
place in the box. Loss of time at this juncture owing to uncertain
movements is a fruitful source of failure among beginners.
_Keep the box tightly closed_ from the moment the food is put into it
until it is entirely done, as if for any reason the box is opened before
the appointed time, the contents must be _reheated to boiling point_
before being replaced.
The _time for cooking foods on the stove_, previous to putting them into
the cooker, is usually very short. Food in large, solid masses, as ham,
pot roasts, moulds of bread, etc., must be boiled until thoroughly
heated to the centre, obviously requiring longer boiling the larger and
denser the pieces are. Food that is broken and less compact will be
readily penetrated by heat and will be boiling hot nearly or quite as
soon as the surrounding water. Such foods need only a moment’s brisk
boiling before being put into the cooker. Cereals, although in fine
particles, easily settle into a dense, impenetrable mass during the long
period of undisturbed cooking, unless boiled until they are slightly
thickened.
The _length of time for cooking in the cooker_ depends upon several
factors: (1) the kind of cooker, whether well or ill packed, and whether
good or poor insulating material is used; (2) the skill of the cook in
getting the kettle into the box quickly; (3) the amount, toughness,
density, and size of the pieces; (4) whether hard or soft water is used.
If hard water is used foods require more cooking to become tender than
with soft water. Hard water may be softened, however, by the addition of
a little baking soda. The time given in this book is adapted to a
home-made cooker, well packed with any of the materials suggested in the
section giving directions for packing the cookers. With some commercial
cookers a shorter time may be sufficient.
It is frequently stated that few foods are injured by overcooking, but
while this is true of a great many foods, it has not proved to be the
case with all. Potatoes, rice, custards, raised mixtures, such as
dumplings, suet pudding, and brown bread, as well as many other foods,
are decidedly injured by overcooking. The recipes generally state the
minimum and maximum time which each food should have. This information
will also be found easily accessible in the classified index. There is
danger in leaving meats or soup stock or even cereals in the cooker long
after they have cooled down, as they will be likely to spoil.
Needless to say, careful reading of all the directions given, and
following them in every particular, will be necessary until one becomes
well acquainted with this novel method of cookery. Mistakes in
temperature tests, in measuring, in time, and in other conditions, may
result in failures, which must not be imputed to the cooker, but to the
cook.
It will probably not be long, after the first experiment with a cooker,
before several compartments are fitted up; in which case it is difficult
to remember what food is in each and at what time it is to be removed,
since it is left for so many hours. To meet this difficulty a slate,
hung in the kitchen near the box, will be found a great convenience. It
may be permanently ruled and arranged in the form of a table, to be
filled out with pencil. A good form to use is the one given below. The
compartments may be numbered or described.
+----------------+----------------+----------------+----------------+
| Compartment | Food | Time put in |Time for removal|
+----------------+----------------+----------------+----------------+
| | | | |
+----------------+----------------+----------------+----------------+
| | | | |
+----------------+----------------+----------------+----------------+