BAKING
In discussing the method of transforming flour into bread it will be
convenient to begin by describing in detail one general method. The
modifications used for obtaining bread of different kinds, and for
dealing with flours of different qualities will be shortly discussed
later when they can be more readily understood.
Bread may be defined as the product of cooking or baking a mixture of
flour, water, and salt, which is made porous by the addition of yeast.
It is understood to contain no other substances than these--flour,
salt, water and yeast.
In the ordinary process the first step is to weigh out the flour which
it is proposed to bake. This is then transferred to a vessel which in a
commercial bakery is usually a large wooden trough, in a private house
an earthenware bowl. The necessary amount of yeast is next weighed out
and mixed with water. Nowadays compressed or German yeast is almost
always used at the rate of 1 to 2 lbs. per sack or 280 lbs. of flour.
For smaller quantities of flour relatively more yeast is needed, for
instance 2 ozs. per stone. Formerly brewers’ yeast or barm was used,
but its use has practically ceased because it is difficult to obtain
of standard strength. Some people who profess to be connoisseurs of
bread still prefer it because as they say it gives a better flavour
to the bread. The water with which the yeast is mixed is warmed so as
to make the yeast more active. The flour is then heaped up at one end
of the vessel in which the mixing is to take place, and salt at the
rate of 2 to 5 lbs. per sack is thoroughly stirred into it. A hollow
is then made in the heap of flour into which the mixture of yeast and
water is poured. More warm water is added so that enough water in all
may be present to convert all, or nearly all, the flour into dough of
the required consistency. When dealing with a flour with which he is
familiar the baker knows by experience how much water he requires per
sack. In the case of an unaccustomed brand of flour he determines the
amount by a preliminary trial with a small quantity (Figs. 16 and 17).
Flour from the heap is then stirred into the water until the whole of
the flour is converted into a stiff paste or dough as it is called.
By this method a little dry flour will always separate the dough from
the sides of the vessel and this will prevent the dough from sticking
to the vessel and the hands. The dough is then thoroughly worked or
kneaded so as to ensure the intimate mixture of the ingredients. The
vessel is then covered to keep the dough warm. In private houses
this is ensured by placing the vessel near the fire. In bakeries the
room in which the mixing is conducted is usually kept at a suitable
temperature. The yeast cells which are thoroughly incorporated in the
dough, find themselves in possession of all they require to enable them
to grow. The presence of water keeps them moist, and dissolves from
the flour for their use sugar and salts: the dough is kept warm as
above explained. Under these conditions active fermentation takes place
with the formation of alcohol and carbon dioxide gas. The alcohol is
of no particular consequence in bread making, the small amount formed
is probably expelled from the bread during its stay in the oven. The
carbon dioxide, however, plays a most important part. Being a gas it
occupies a large volume, and its formation throughout the mass of the
dough causes the dough to increase greatly in volume. The dough is said
by the housewife to rise, by the professional baker to prove.
[Illustration:
Fig. 16. Apparatus arranged for a baking test. Four loaves
which have just been scaled and moulded are seen in an
incubator where they are left to rise or prove before being
transferred to the oven]
[Illustration:
Fig. 17. The loaves shown in the last figure have just been
baked and are ready to be taken out of the oven, the door of
which is open. Note the different shapes. That on the right
hand is obviously shown by the test to be made from a strong
flour, the other from a very weak flour]
The process of kneading causes the particles of gluten to absorb
water and to adhere to one another, so that the dough may be regarded
as being composed of innumerable bubbles each surrounded by a thin
film of gluten, in or between which lie the starch grains and other
constituents of the flour. Each yeast cell as above explained forms a
centre for the formation of carbon dioxide gas, which cannot escape
at once into the air, and must therefore form a little bubble of
gas inside the particular film of gluten which happens to surround
it. The expansion of the dough is due to the formation inside it of
thousands of these small bubbles. It is to the formation of these
bubbles too that the porous honey-combed structure of wheaten bread is
due. Also since the formation of the bubbles is due to the retention
of the carbon dioxide by the gluten films, such a porous structure is
impossible in bread made from the flour of grains which do not contain
gluten.
The rising of the dough is usually allowed to proceed for several
hours. The baker finds by experience how long a fermentation is
required to give the best results with the flours he commonly uses.
When the proper time has elapsed, the dough is removed from the trough
or pan in which it was mixed to a board or table, previously dusted
with dry flour to prevent the dough adhering to the board or to the
hands. It is then divided into portions of the proper weight to
make loaves of the desired size. This process is known technically
as scaling. Usually 2 lbs. 3 ozs. of dough is allowed for baking a 2
lb. loaf. Each piece of dough is now moulded into the proper shape if
it is desired to bake what is known as a cottage loaf, or placed in
a baking tin if the baker is satisfied with a tinned loaf. In either
case the dough is once more kept for some time at a sufficiently warm
temperature for the yeast to grow so that the dough may once more be
filled with bubbles of carbon dioxide gas. As soon as this second
rising or proving has proceeded far enough the loaves are transferred
to the oven. Here the intense heat causes the bubbles of gas inside
the dough to expand so that a sudden increase in the size of the loaf
takes place. At the same time the outside of the loaf is hardened and
converted into crust.
After remaining in the oven for the requisite time the bread is
withdrawn and allowed to cool as quickly as possible, after which it is
ready for use or sale.
The method of baking which has been described above is known as the
off-hand or straight dough method. It possesses the merit of rapidity
and simplicity, but it is said by experts that it does not yield the
best quality of bread from certain flours. Perhaps the commonest
variation is that known as the sponge and dough method, which is
carried out as follows. As before, the requisite amount of flour is
weighed out into the mixing trough, and a depression made in it for
the reception of the water and yeast. These are mixed together in the
proper proportions, enough being taken to make a thick cream with
about one quarter of the flour. This mixture is now poured into the
depression in the flour, and enough of the surrounding flour stirred
into it to make a thick cream or sponge as it is called. At the same
time a small quantity of salt is added to the mixture. The sponge is
allowed to ferment for some hours, being kept warm as in the former
method. As soon as the time allowed for the fermentation of the sponge
has elapsed, more water is added, so that the whole or nearly the whole
of the flour can be worked up into dough. This dough is immediately
scaled and moulded into loaves, which after being allowed to prove
or rise for some time are baked as before. This method is used for
flours which do not yield good bread when they are submitted to long
fermentation. In such cases the mellow flours, which will only stand a
very short fermentation, are first weighed out into the mixing trough,
and a depression made in the mass of flour into which a quantity of
strong flour which can be fermented safely for a long time is added. It
is this last addition which is mixed up into the sponge to undergo the
long preliminary fermentation. The rest of the flour is mixed in after
this first fermentation is over, so that it is only subjected to the
comparatively slight fermentation which goes on in the final process of
proving.
Many other modifications are commonly practised locally, their object
being for the most part to yield bread which suits the local taste.
It will suffice to mention one which has a special interest. In this
method the essentially interesting point is the preparation of what is
known as a ferment. For this purpose a quantity of potatoes is taken,
about a stone to the sack of flour. After peeling and cleaning they
are boiled and mashed up with water into a cream. To this a small
quantity of yeast is added and the mixture kept warm until fermentation
ceases, as shown by the cessation of the production of gas. During
this fermentation the yeast increases enormously, so that a very small
quantity of yeast suffices to make enough ferment for a sack of flour.
The flour is now measured out into the trough, and the ferment and some
additional water and salt added so that the whole can be worked up into
dough. Scaling, moulding, and baking are then conducted as before. This
method was in general use years ago when yeast was dear. It has fallen
somewhat into disuse in these days of cheap compressed yeast, in fact
the use of potatoes nowadays would make the process expensive.
In private houses and in the smaller local bakeries the whole of the
processes described above are carried out by hand. During the last
few decades many very large companies have been formed to take up
the production of bread on the large scale. This has caused almost
a revolution of the methods of manipulating flour and dough, and in
many cases nowadays almost every process in the bakery is carried out
by machinery. In many of the larger bakeries doughing and kneading
are carried out by machines, and this applies also to the processes
of scaling and moulding. A similar change has taken place too in the
construction of ovens. Years ago an oven consisted of a cavity in a
large block of masonry. Wood was burned in the cavity until the walls
attained a sufficiently high temperature. The remains of the fuel were
then raked out and the bread put in and baked by radiation from the hot
walls.
Nowadays it is not customary to burn fuel in the oven itself, nor is
the fuel always wood or even coal. The fuel is burned in a furnace
underneath the oven, and coal or gas is generally used. Sometimes
however the source of heat is electricity. In all cases it is still
recognised that the heat should be radiated from massive solid walls
maintained at a high temperature. In the latest type of oven the heat
is conducted through the walls by closed iron tubes containing water,
which of course at the high temperatures employed becomes superheated
steam. It is recognised that the ovens commonly provided in modern
private houses, whether heated by the fire of the kitchen range, or by
gas, are not capable of baking bread of the best quality, because their
walls do not radiate heat to the same degree as the massive walls of a
proper bake oven.
It is commonly agreed that bread, in the usual acceptation of the term,
should contain nothing but flour, yeast, salt, and water; or if other
things are present they should consist only of the products formed by
the interaction of these four substances in the process of baking.
Millers and bakers have, however, found by experience that the addition
of certain substances to the flour or to the dough may sometimes enable
them substantially to improve the market value of the bread produced by
certain flours. The possible good or bad effect of such additions on
the public health will be discussed in a later chapter. It may be of
interest here to mention some of the substances which are commonly used
as flour or bread improvers by millers and bakers, and to discuss the
methods by which they effect their so called improvements.
In a former chapter we have discussed the quality of wheat from the
miller’s point of view, and during the discussion certain views were
enunciated on the subject of strength. It was pointed out that a strong
flour was one which would make a large well-shaped loaf, and that the
size of the loaf was dependent on the flour being able to provide sugar
for the yeast to feed upon right up to the moment when the loaf goes
into the oven. This can only occur when the flour contains an active
ferment which keeps changing the starch into sugar. That this view is
generally accepted in practice is shown by the fact that, when using
flours deficient in such ferment, bakers commonly add to the flour,
yeast, salt, and water, a quantity of malt extract, the characteristic
constituent of which is the sugar producing ferment of the malt. This
use of malt extract is now extending to the millers, several of whom
have installed in their mills plant for spraying into their flour a
strong solution of malt extract. It seems to be agreed by millers and
bakers generally that such an addition to a flour which makes small
loaves distinctly increases the size of the loaf. There can be no doubt
that this effect is produced by the ferment of the malt extract keeping
up the supply of sugar, and thus enabling the yeast to maintain the
pressure of gas in the dough right up to the moment when it goes into
the oven.
The view that the shape of the loaf is due to the effect of salts, and
particularly of phosphates, on the coherence of the gluten has also
been put to practical use by the millers and the bakers. Preparations
of phosphates under various fancy names are now on the market, and are
bought by bakers for adding to the flour to strengthen the gluten and
produce more shapely loaves. A few millers too are beginning to spray
solutions of phosphates into their flours with the same object in view,
and such additions are said to make material improvements in the shape
of the loaf produced by certain weak flours.
These two substances, malt extract and phosphates, are added to the
flour with the definite object of improving the strength and thus
making larger and more shapely loaves. But there is a second class of
substances which are commonly added to flours, not in the mill but in
the process of bread making, with the object of replacing yeast. Yeast
is used in baking in order that it may form gas inside the dough and
thus produce a light spongy loaf. Exactly the same gas can be readily
and cheaply produced by the interaction of a carbonate with an acid.
These substances will not react to produce acid as long as they remain
dry, but as soon as they are brought into close contact with each other
by the presence of water, reaction begins and carbon dioxide gas is
formed. These facts are taken advantage of in the manufacture of baking
powders and self-rising flours. Baking powders commonly consist of
ordinary bicarbonate of soda mixed with an acid or an acid salt, such
as tartaric acid, cream of tartar, acid phosphate of lime, or acid
phosphate of potash. One of these latter acid substances is mixed in
proper proportions with the bicarbonate of soda, and the mixture ground
up with powdered starch which serves to dilute the chemicals and to
keep them dry. A small quantity of the baking powder is mixed with the
flour before the water is added to make the dough. The presence of the
water causes the acid and the carbonate to give off gas which, as in
the case of the gas formed by the growth of yeast, fills the dough with
bubbles which expand in the oven and produce light spongy bread. When
using baking powders in place of yeast it must not be forgotten that
gas formation in most cases begins immediately the water is added, and
lasts for a very short time. Consequently the dough must be moulded and
baked at once or the gas will escape. This is not the case, however,
with those powders which are made with cream of tartar, for this
substance does not react with the carbonate to any great extent until
the dough gets warm in the oven. For some purposes it is customary to
use carbonate of ammonia, technically known as volatile, in place of
baking powder. This substance is used alone without any addition of
acid, because it decomposes when heated and forms gas inside the dough.
Sometimes too one or other of the baking powders above described are
added to the flour by the miller, the product being sold as self-rising
flour. Such flour will of course lose its property of self-rising if
allowed to get damp. Occasionally objectionable substances are used in
making baking powders of self-rising flours. Some baking powders for
instance contain alum which is not a desirable addition to any article
of human food. Baking powders and self-rising flours are far more
frequently used by house-wives for making pastry or for other kinds of
domestic cookery than for breadmaking.
Bread is made on the large scale without the intervention of yeast
by the aeration process, which is carried out as follows. A small
quantity of malt is allowed to soak in a large quantity of water, and
the solution thus obtained is kept warm so that it may ferment. This
charges the solution with gas and at the same time produces other
substances which are supposed to give the bread a good flavour. Such a
solution too retains gas much better than pure water. This solution is
then mixed with a proper proportion of flour inside a closed vessel,
carbon dioxide gas made by the action of acid on a carbonate being
pumped into the vessel whilst the mixing is in progress. The mixing
is of course effected by mechanical means. As soon as the dough is
sufficiently mixed, it is allowed to escape by opening a large tap
at the bottom of the mixing vessel. This it does quite readily being
forced out by the pressure of gas inside. As it comes out portions of
suitable size to make a loaf are cut off. These are at once moulded
into loaves and put into the oven. The gas which they contain expands,
and light well risen bread is produced. This process is especially
suited for wholemeal and other flours containing much offal, which
apparently do not give the best results when submitted to the ordinary
yeast fermentation.
Before closing this chapter it may be of interest to add a short
account of the sale of bread. Bread is at the present time nominally
sold by weight under acts of Parliament passed about 80 years ago.
That is to say, a seller of bread must provide in his shop scales and
weights which will enable him to weigh the loaves he sells. No doubt
he would be prepared to do so if requested by a customer, in which
case he would probably make up any deficiency in weight which might be
found by adding as a makeweight a slice from another loaf. For this
purpose it is commonly accepted that the ordinary loaf should weigh two
pounds. But in practice this does not occur, for practically the whole
of the bread which is sold in this country is sold from the baker’s
cart, which delivers bread at the houses of customers, and not over
the counter. Customers obviously cannot be expected to wait at their
doors whilst the man in the cart weighs each loaf he is delivering
to them. In actual practice therefore the bread acts, as they are
called, are really a dead letter, and bread is sold by the loaf and
not by weight, though it must be remembered that the loaf has the
reputed weight of two pounds. There are no doubt slight variations
from this weight, but for all practical purposes competition nowadays
is quite as effective a check on the _bona fides_ of the bread seller
as enforced sale by weight would be likely to be. If a baker got the
reputation of selling loaves appreciably under weight his custom would
very soon be transferred to one of his more scrupulous competitors.
Altogether it may be concluded that the present unregulated method of
sale does not work to the serious disadvantage of the consumers. A
little consideration will show that the sale of bread could only be put
on a more scientific basis by the exercise of an enormous amount of
trouble, and the employment of a very numerous and expensive staff. No
doubt the ideally perfect way of regulating the sale of either bread
or any other feeding stuff would be to enact that it should be sold by
weight, and that the seller should be compelled to state the percentage
composition, so that the buyer could calculate the price he was asked
to pay per unit of actual foodstuff. Now bread normally contains 36
per cent. of water, but this amount varies greatly. A two pound loaf
kept in a dry place may easily lose water by evaporation at the rate of
more than an ounce a day. The baker usually weighs out 2 lbs. 3 ozs.
of dough to make each two pound loaf, and this amount yields a loaf
which weighs in most cases fully two pounds soon after it comes out
of the oven. But if the weather is hot and dry such a loaf may very
well weigh less than two pounds by the time it is delivered to the
consumer. In other words the baker cannot have the weight of the loaves
he sells under complete control. Furthermore the loss in weight when a
loaf gets dry by evaporation is due entirely to loss of water, and does
not decrease the amount of actual foodstuff in the loaf. To sell bread
in loaves guaranteed to contain a definite weight of actual foodstuff
might be justified scientifically, but practically it would entail
so great an expense for the salaries of the inspectors and analysts
required to enforce such a regulation that the idea is quite out of
the question. Practically, therefore, the situation is that it would
be unfair to enforce sale by weight pure and simple for the weight of
a loaf varies according to circumstances which are outside the baker’s
control, and further because the weight of the loaf is no guarantee of
the weight of foodstuff present in it. Nor is it possible to enforce
sale by guarantee of the weight of foodstuff in the loaf, for to do
so would be too troublesome and expensive. Finally the keenness of
competition in the baking trade may be relied on to keep an efficient
check on the interests of the consumer. Quite recently an important
public authority has published the results of weighing several
thousand loaves of bread purchased within its area of administration.
The results show that over half the two pound loaves purchased
were under weight to the extent of five per cent. on the average.
Legislation is understood to be suggested as the result of this report,
in which case it is to be hoped that account will be taken of the fact
that the food value of a loaf depends not only on its weight but also
on the percentage of foodstuffs and water which it contains.