individuals, or by spore formation. Bacteria are very abundant, being found everywhere. Some are disease- producing; many are non-disease-producing. Most organic foods are injured or in time destroyed by the presence in them and growth of molds, yeast, and bacteria. To preserve food the growth of these organisms must be pre- vented. Fresh air and sunshine are nature's disinfectants and they check the growth of germs or even destroy them ; hence the necessity of fresh air and sunshine in all parts of a house. Molds, yeast, and bacteria are destroyed by heat and by certain chemicals. Their growth is checked by low tem- perature, by the removal of water, by the aromatic oils of spices, by an excess of sugar or salt, by the presence of smoke, and by certain acids. While such chemicals as for- maldehyde, salicylic acid, benzoate of soda, will preserve foods indefinitely by destroying or checking the growth of germs, their presence even in very small amounts is harmful to the body, hence their use as food preservatives should be forbidden by the Pure Food Laws. Harmless Methods of Food Preservation 1. Canning — destruction of germs by heat and the sub- sequent exclusion of germs. 2. Preserving — destruction of germs by heat and the preventing of their growth by thick sugar syrup. 3. Pickling — prevention of growth of germs by acid and spices. 4. Smoking — prevention of growth of germs by smoke. 5. Salting — prevention of growth of germs by presence of salt. 52 DOMESTIC SCIENCE 6. Cold Storage — prevention of growth of germs by tem- perature of 37° F. 7. Drying — prevention of growth of germs by removing water. Harmful Methods of Food Preservation Use of formaldehyde, salicylic acid, borax, boric acid, ben- zoate of soda, " canning compounds," and alcohol. Sterilization and Pasteurization. — Sterilization is the com- plete destruction of bacteria. When a thing is free from bacteria and other forms of life, it is sterile, no matter how the condition is brought about. The purpose of pasteurization is to sterilize sufficiently to make a food safe without injuring its flavor or digestibility. Few bacteria can live in a temperature above 157° F. Some bacteria have the power of reproducing by the forming of spores which will resist such heat as may destroy the bacteria themselves. Dry heat destroys bacteria with certainty only at a temperature of 284° F. Pasteurization is the raising of a substance to a tempera- ture of from 155° F. to 170° F. and the maintaining of this temperature for twenty minutes, when the substance should be cooled rapidly ; by this process most of the harmful germs are supposed to be destroyed. Canning and Preserving. — The purpose of canning is to destroy by heat germs already present in the food and to exclude the entrance of other germs. The purpose of pre- serving is to destroy by heat germs already present and to protect the food by means of a thick sugar syrup. The factors most essential in the processes of canning and preserving are (1) the complete sterilization of the food to be FOOD PRESERVATION 53 preserved, (2) the complete sterilization of the cans or jars into which the food is to be placed, (3) the complete sealing of the jars to prevent the entrance of germs. Vegetables contain more spore-forming bacteria than do fruits, hence are more difficult to preserve. Methods of Fruit Preserving:

AI-modernized reading of the original text

individuals, or by spore formation. Bacteria are very abundant, being found everywhere. Some are diseaseproducing; many are non-disease-producing. Most organic foods are injured or in time destroyed by the presence in them and growth of molds, yeast, and bacteria. To preserve food the growth of these organisms must be prevented. Fresh air and sunshine are nature's disinfectants and they check the growth of germs or even destroy them ; hence the necessity of fresh air and sunshine in all parts of a house. Molds, yeast, and bacteria are destroyed by heat and by certain chemicals. Their growth is checked by low temperature, by the removal of water, by the aromatic oils of spices, by an excess of sugar or salt, by the presence of smoke, and by certain acids. While such chemicals as formaldehyde, salicylic acid, benzoate of soda, will preserve foods indefinitely by destroying or checking the growth of germs, their presence even in very small amounts is harmful to the body, hence their use as food preservatives should be forbidden by the Pure Food Laws. Harmless Methods of Food Preservation 1. Canning — destruction of germs by heat and the subsequent exclusion of germs. 2. Preserving — destruction of germs by heat and the preventing of their growth by thick sugar syrup. 3. Pickling — prevention of growth of germs by acid and spices. 4. Smoking — prevention of growth of germs by smoke. 5. Salting — prevention of growth of germs by presence of salt. 6. Cold Storage — prevention of growth of germs by temperature of 37° F. 7. Drying — prevention of growth of germs by removing water. Harmful Methods of Food Preservation Use of formaldehyde, salicylic acid, borax, boric acid, benzoate of soda, " canning compounds," and alcohol. Sterilization and Pasteurization. — Sterilization is the complete destruction of bacteria. When a thing is free from bacteria and other forms of life, it is sterile, no matter how the condition is brought about. The purpose of pasteurization is to sterilize sufficiently to make a food safe without injuring its flavor or digestibility. Few bacteria can live in a temperature above 157° F. Some bacteria have the power of reproducing by the forming of spores which will resist such heat as may destroy the bacteria themselves. Dry heat destroys bacteria with certainty only at a temperature of 284° F. Pasteurization is the raising of a substance to a temperature of from 155° F. to 170° F. and the maintaining of this temperature for twenty minutes, when the substance should be cooled rapidly ; by this process most of the harmful germs are supposed to be destroyed. Canning and Preserving. — The purpose of canning is to destroy by heat germs already present in the food and to exclude the entrance of other germs. The purpose of preserving is to destroy by heat germs already present and to protect the food by means of a thick sugar syrup. The factors most essential in the processes of canning and preserving are (1) the complete sterilization of the food to be preserved, (2) the complete sterilization of the cans or jars into which the food is to be placed, (3) the complete sealing of the jars to prevent the entrance of germs. Vegetables contain more spore-forming bacteria than do fruits, hence are more difficult to preserve. Methods of Fruit Preserving:

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