The science and practice of cheese-making : a treatise on the manufacture of American Cheddar cheese and other varieties : intended as a text-book for the use of dairy teachers and students in classroom and workroom ... . erments are destroyed by heat, thetemperature of boiling water, in most cases, com-pletely destroying their power to act. Their activityis checked by low temperatures, but, when againwarmed, they renew their activity. (4) The actionof ferments is checked or prevented by many sub-stances. (5) When the products formed by fermentsaccumulate in certain amounts, the ferment action
The science and practice of cheese-making : a treatise on the manufacture of American Cheddar cheese and other varieties : intended as a text-book for the use of dairy teachers and students in classroom and workroom ... . erments are destroyed by heat, thetemperature of boiling water, in most cases, com-pletely destroying their power to act. Their activityis checked by low temperatures, but, when againwarmed, they renew their activity. (4) The actionof ferments is checked or prevented by many sub-stances. (5) When the products formed by fermentsaccumulate in certain amounts, the ferment actionusually stops. (6) All ferments are closely con-nected with living processes. Organized ferments, or living micro-organismscapable of causing fermentations, are divided into MICRO-ORGANISMS AND ENZYMS 287 several classes; but those of greatest interest in con-nection with cheddar cheese-making are called bac-teria. These are the smallest conceivable forms ofplant life. Each individual consists of a single cell,averaging in diameter one-thirty-thousandth of aninch. (i) Kinds.—Bacteria appear in three generalvarieties of form: (a) Ball (coccus), (b) short rod(bacillus), and (c) corkscrew (spirillum). (). FIG. 39—BALL-SHAPED BAC-TERIA (coccus). (Rogers) FIG. 40—CHAINS OF BALL-SHAPED (coccus) BAC-TERIA (Rogers) (2) Method of grozvth and reproduction.—Theymultiply in number, or reproduce, by simple division;that is, when a cell grows in size, it increases morein one direction, so as to result in lengthening outslightly, and a partition forms across the cell, thusproducing two new cells in place of the old one; andthen each of these subdivides again and so on con-tinuously. Some kinds of bacteria form spores inthe cells; these are to bacteria what seeds are to 2S^ SCIENCE AND PRACTICE OF CHEESE-MAKING higher plants. Spores are not so easily killed by heatas are bacteria. Under favorable conditions, therapidity of growth of bacteria is remarkable. Thus,in some cases
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Keywords: ., bookcentury1900, bookdecade1920, bookidsciencepract, bookyear1921
