A Treatise on Baking
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Pure water is merely a compound made up of Hydrogen and Oxygen. Therefore, in the language of the chemist, water is expressed by the symbols H2O. This refers to pure distilled water. However, the average city or well water available contains a certain small amount of mineral matter dissolved in it.
A. FORMATION OF THE DOUGH
Without water, the formation of dough would be impossible. When mixed with flour, water unites with gliadin and glutenin of the flour resulting in the substance known as gluten, that tenacious, elastic material which forms the skeleton of the dough and finished loaf. The taking up of water by the glutenin and gliadin in the formation of gluten is often spoken of as the hydration of the gluten. Some of the water also combines with the starch of the flour. This wetted starch is thoroughly incorporated into the gluten by the mixing process and the result is the uniform, pliable, plastic substance called dough.
When broken up and stirred into water, yeast forms what is known as a “suspension” or a very uniform mixture with the water. In baking circles and from a practical standpoint, this mixture is often called a yeast “solution.” When this is incorporated into the dough batch in the mixer, the yeast cells are completely and uniformly distributed throughout the entire mass of dough.
With the exception of the flour and the shortening, the other ingredients used in the dough go into solution in the water and in the mixing process also become a structural part of the dough. The shortening is thoroughly worked into the dough batch mechanically by the mixing process.
B. EFFECT OF WATER ON DOUGH FERMENTATION
Water plays an important part in the fermentation of the dough mainly from two standpoints.
(a) Water makes possible the pliable and extensible properties of the dough so that in this form it can be raised by the carbon dioxide gas resulting from yeast activity.
(b) In order to enable the yeast enzymes to function, it is necessary that the required food substances supporting the yeast in the dough, first become dissolved in water of the dough so that in this form, they can diffuse through the wall or membrane surrounding the yeast cell and thus become available for direct utilization by the yeast throughout the entire panary fermentation process. The activity of the yeast itself also requires the presence of water.
C. EFFECT OF WATER ON THE EATING QUALITIES AND FRESHNESS OF BREAD
The presence of water makes possible the characteristic porosity, and general good eating qualities of the loaf. A dough lacking water when baked would result in a dry brittle product. Starch and gluten properly combined with water in the dough “sets” by the heat of the oven. When cooked in this manner by the baking process these constituents are in their most appetizing and easily digestible condition. The presence of water also aids in rendering the crust of the loaf soft, tender and appealing to the eye.
Moisture in bread and other baked goods imparts the desirable characteristic of freshness. However, according to the work done by Katz and Ostwald the period of freshness is not due alone to the amount of moisture contained but also to the manner in which the moisture is retained in the loaf. In other words, staling is said to be caused not only by loss of moisture from the loaf through actual drying, but also to the migration of some water from the starch to the other constituents of the loaf, mainly the gluten. An explanation of Bread Staling will be found in Chapter XV.
The exact amount of water to be used with any flour can be determined by absorption and baking tests described under the Chapter II on Wheat and Flour.
This amount of water absorbed and carried by any flour varies with the type of flour, its age and stability. Slack doughs will ferment faster than stiff doughs,—but it must be remembered that the amount of water to be used in any case should be such that the resulting dough will not soften unduly or become sticky during handling or in other words will have the proper consistency or viscosity in order to insure a finished baked product of the best quality . Different types of yeast raised doughs of course may vary slightly in the consistency desired depending on the nature of the goods being made.
The amount of water retained in the loaf materially affects the yield of bread secured. From a commercial standpoint therefore, the retention of as much moisture as possible consistent with the highest quality product is advantageous. However, it must be remembered that over-hydration of the dough in the desire to secure an increased yield will prove disastrous to the quality of the finished baked bread.
According to the government standards, it is not permissible for bread one hour or more after baking to contain more than 38% moisture, based on the actual weight of the loaf.
Ordinary water secured from public water supplies, well, etc., contains dissolved in it, very small amounts of mineral compounds. As a matter of fact, distilled water and rain water are the only forms which are free from some mineral salts.
In order to be suitable for baking purposes any water should naturally be perfectly satisfactory for drinking purposes. Many large cities use chlorine for the purification of the water. Under normal conditions there is never enough used to interfere with the fermentation, and furthermore, when comparatively large quantities are necessary it should all be used UP in the oxidation of the organic matter before the water reaches the bakery. Several methods of purification of the water supplies are used but none of them give the well informed baker any concern.
Water in different sections of the country varies considerably in the kind and amount of mineral compounds contained. A baker in any one locality using water from one source, undoubtedly has adjusted the fermentation of his doughs so as to properly conform to the water conditions prevailing in that particular section. However we must remember that in any one place, minor variations in the water may very likely occur with the seasons, and accordingly necessary changes will have to be made in governing the fermentation process. If the nature of the water is causing difficulty in the manufacture of baked goods it is advisable to secure a very recent analysis of the City Water from the City Water Department and consult a chemist concerning necessary treatment of the water, or changes to be made in the fermentation process.
There are, in general, three different classes of industrial water each having a somewhat different effect on the dough. These are as follows:
A. HARD WATER
This is water which contains appreciable amounts of the carbonate or sulphate of magnesium or calcium. One very noticeable feature about hard water is the great difficulty with which it forms a lather with soap. Water containing only the carbonates is called “Temporary” hard water, because these carbonates will separate out when the water is boiled and can be removed thus rendering the water soft. Water containing sulphates is termed “Permanent” hard water inasmuch as sulphates do not separate out when the water is boiled. Inasmuch as some mineral salts tend to strengthen the gluten, a certain degree of hardness in water is therefore desirable. Furthermore, the sulphate assists to a small extent in furnishing mineral nutrition to the yeast. However, an excessively hard water retards the progress of fermentation by toughening the gluten too greatly. Increased amounts of yeast usually will assist in overcoming this condition by bringing about a more vigorous conditioning or softening of the gluten,—thus preventing coarseness and harshness in the finished loaf.
B. SOFT WATER
This is water which is relatively free of the carbonates or sulphates of Calcium or Magnesium. Soft water forms a lather freely with soap. Real soft water used for bread making has a tendency to soften the gluten and result in a soft sticky dough. This condition, while not lessening
the activity of the yeast, considerably offsets the usual beneficial effects of the fermentation process in the dough batch, unless more salt is used. The use of Arkady eliminates the undesirable effects of soft water by supplying the necessary mineral salts for optimum gluten development and healthy dough fermentation.
C. ALKALINE WATER
This is water which contains in solution alkali substance such as sodium carbonate which imparts to the water the power to partially neutralize or reduce the natural acidity of the dough created by fermentation. The degree of alkalinity of water depends of course, on the amount of the alkali salts present. Alkaline water may also possess a reasonable degree of hardness. While in certain exceptional cases water is sufficiently alkaline to require special treatment, such cases are rare. Nevertheless, appreciable alkalinity in water has a tendency to dissolve the gluten, which of course, means a weaker dough. Furthermore, alkaline water by overcoming some of the acidity of the dough decreases the activity of the enzymes of the yeast and flour, thus impeding the normal progress of panary fermentation and interfering with the normal ripening of the gluten. The use of a small amount of vinegar in the dough batch will aid in overcoming the usual disadvantages of such water in breadmaking.
Humidity or the amount of moisture in the air, including steam in the proof box and oven exercises a very noticeable effect on panary fermentation and the quality of the finished baked products. This important subject is discussed in detail in Chapters X and XII.
B. BOILER SCALE
It is a well-known fact that noticeably hard waters produce scale to form in boilers causing trouble and expense. In order to eliminate this condition, such water must be especially treated to render it soft and fit for boiler use. Special boiler compounds and water treating devices are employed for this purpose.