. Cyclopedia of farm crops : a popular survey of crops and crop-making methods in the United States and Canada. Agriculture -- Canada; Agriculture -- United States; Farm produce -- Canada; Farm produce -- United States. Fig. 237. Forms of yeasts of different kinds. enemies of preserves, jellies and the like. (Figs. 237, 238.) These growths usually are killed in a few minutes at the temperature of boiling water, 212° Fahr. A lower degree of heat continued for a longer period — half an hour or more — is often as effectual and less detrimental to the flavor and texture of the fruit. The spores, o
. Cyclopedia of farm crops : a popular survey of crops and crop-making methods in the United States and Canada. Agriculture -- Canada; Agriculture -- United States; Farm produce -- Canada; Farm produce -- United States. Fig. 237. Forms of yeasts of different kinds. enemies of preserves, jellies and the like. (Figs. 237, 238.) These growths usually are killed in a few minutes at the temperature of boiling water, 212° Fahr. A lower degree of heat continued for a longer period — half an hour or more — is often as effectual and less detrimental to the flavor and texture of the fruit. The spores, or undeveloped organ- isms, resist heat that would be fatal to those fully grown, so in lab- oratories or canning factories steam, under pressure, is used to secure a temperature much higher than 212° Fahr., and thus wholly to sterilize the food. Here the housekeeper cannot compete with the factories, and must practice intermittent sterilization as was done long before the existence and habits of these microorganisms were known. The material to be sterilized is heated to the boiling point and kept there for half an hour on three or more successive days. Between these scaldings it is left at an ordinary tempera- ture, that the spores may germinate and become active organisms. These are then killed by the next heating, and after the final boiling the exclusion of air prevents the entrance of others. It is essential that everything exposed to the air, filled as it is with " germs," should be sterilized before it comes in direct or indirect contact with the food to be preserved. Fruits are constantly exposed while growing, or in market, and their skins harbor vast numbers of microorganisms; hence they must be thoroughly washed. The removal of skins from peaches, tomatoes and like products by scalding has more than one beneficial effect. If pared fruit must stand before cooking, it should be dropped into water with lemon juice or vinegar in. Fig. 238. Molds. A, Mucor,
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