Page:The Boston cooking-school cook book (1910).djvu/77

 keep in shape; if allowed to pass through fingers it will feel slightly granular. Take pastry flour in the hand, close hand tightly, open, and flour will be in shape, having impression of the lines of the hand, and feeling soft and velvety to touch. Flour should always be sifted before measuring.

Entire wheat flour differs from ordinary flour inasmuch as it contains all the gluten found in wheat, the outer husk of kernels only being removed, the remainder ground to different degrees of fineness and left unbolted. Such flours are sold by the different health-food companies, who have agencies in the large cities. Franklin Mills, Old Grist Mill, and Health Food flours are included in this class.

Gluten, the proteid of wheat, is a gray, tough, elastic substance, insoluble in water. On account of its great power of expansion, it holds the gas developed in bread dough by fermentation, which otherwise would escape.

Yeast

Yeast is a microscopic plant of fungous growth, and is the lowest form of vegetable life. It consists of spores, or germs, found floating in air, and belongs to a family of which there are many species. These spores grow by budding and division, and multiply very rapidly under favorable conditions, and produce fermentation.

Fermentation is the process by which, under influence of air, warmth, moisture, and some ferment, sugar (or dextrose, starch converted into sugar) is changed into alcohol (C_{2}H_{5}HO) and carbon dioxide (CO_{2}). The product of all fermentation is the same. Three kinds are considered,—alcoholic, acetic, and lactic. Where bread dough is allowed to ferment by addition of yeast, the fermentation is alcoholic; where alcoholic fermentation continues too long, acetic fermentation sets in, which is a continuation of alcoholic. Lactic fermentation is fermentation which takes place when milk sours.

Liquid, dry, or compressed yeast may be used for raising bread. The compressed yeast cakes done up in tinfoil have long proved satisfactory, and are now almost universally used, having replaced the home-made liquid yeast.