HEAT IN THE PRESERVATION OF FOOD PRODUCTS. 391 



processing of fruits is usually less than that required for vegetables, for the reason 

 that in the presence of the fruit acids the organisms are more easily destroyed than in 

 foods in which acids are not present. 



CONTROLLING FACTORS IN SUCCESSFUL CANNING. 



CLEANLINESS. Too much emphasis could hardly be placed upon the 

 importance of cleanliness throughout the whole preserving process, and 

 especially in the preparation of the product for preserving. Vegetables 

 and fruits that have come in contact with the soil are pretty certain to 

 harbor many spores of bacteria, and if as many of these are removed as 

 is possible by thorough preliminary cleansing, sterilization may be affected 

 with greater ease and surety. The necessity of cleanliness on the part 

 of factory employees is needful only of mention, not only from the aesthetic 

 standpoint, but also from that of good health. 



THE SOUNDNESS OF RAW MATERIAL. The necessity of sound and 

 wholesome raw material is fully as great as that of cleanliness of handling. 

 Foods are never so good as when they are fresh, providing they are sound. 

 It makes no difference how long nor by what method they may be cooked, 

 the quality cannot be bettered; and if food is unsound when it is put into 

 containers for canning, it will never be wholesome for food; and this fact 

 is equally true whether the unsoundness is the result of diseased condi- 

 tions of meats, fruits or other products, or whether it is due to ordinary 

 decay. 



WATER SUPPLY. Another essential for the success of the canner is 

 an ample supply of pure water, chemically and bacteriologically. Water 

 containing iron or sulphur compounds cannot be used for syruping or 

 brining operations, nor is a water containing any percentage of iodine or 

 bromine permissible. It is a well-known bacteriological fact that out- 

 breaks of spoilage have occurred in canneries which could be traced to 

 organisms getting into the goods from the water supply. 



RECEPTACLE. The commercial canner recognizes two essentials for 

 suitable containers for his goods, and these are equally important for the 

 home canner. First, they must be tight, both to prevent the escape of 

 the contained product and the entrance of contaminating material. 

 Second, they must be of a material which will withstand erosion or corro- 

 sion for a reasonable length of time without giving up any notable quan- 

 tity of foreign material to the food product with which they may be in 

 contact. Glass is most satisfactory from this consideration, but for 



