heat in the preservation of. food products 467 



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. Vege- 

 tables that have come into contact with the soil are pretty certain to 

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

 as possible by a thorough preliminary cleansing, sterilization may be 

 effected with greater ease and certainty. The necessity of cleanliness 

 on the part of factory employees is needful only of mention, not only 

 from the esthetic standpoint, but also from that of good heatlth. 



The Soundness of Raw Material. — The necessity of sound- and 

 wholesome raw material is fully as great as that of cleanliness in 

 handling. Foods are never better than when they are fresh. 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 put into the 

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

 fact is equally true whether the unsoundness is the result of diseased 

 I conditions 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. It is a well-known bacteriological 

 fact that outbreaks of spoilage have occurred in canneries, which could 

 be traced to organisms getting into the goods from the water supply. 



Receptacles. — The commercial canner recognizes two essentials for 

 suitable containers for his goods: First, they must be tight, both to 

 prevent the escape of the contained material and the entrance of con- 

 taminating organisms. Second, they must be of a material which will 

 withstand erosion or corrosion for a reasonable length of time, without 

 giving up any notable quantity of foreign material to the food with 

 which they may be in contact. Glass is most satisfactory from this 

 consideration, but for reasons previously stated it is impracticable for 

 use on a commercial scale. The difficulty from erosion in tin cans has 

 been largely overcome by the use of enamelled cans as mentioned above. 



Degree of Heat Required. — The actual sterilization of food 

 products after placing in the containers is termed processing by the 

 commercial canner, and he appreciates fully that upon the care with 

 which the processing is done depends the success of tla.6 entire jpack. 



