EXTENSION COURSE IN VEGETABLE FOODS. 65 



part, not only in those sections of the Southern States where molasses 

 is a large factor of the diet but also in general cooking. The old- 

 fashioned somewhat acid molasses was the result of evaporation in 

 open kettles, a process rarely followed now. 



During the last half century there has been a marked increase in 

 the production of sugar from special varieties of beets. So far as 

 the chemist can discern, this sugar is identical with that made from 

 sugar cane. 



The use of a natural sweet sirup, honey, has been spoken of else- 

 where (p. 36). 



Sorghum sirup, which is not an uncommon domestic product, is 

 less used since corn sirups have been manufactured. 



That sugar is present in a number of vegetables can be easily 

 shown by evaporating the water in which sweet vegetables, like car- 

 rots, peas, or squash have been boiled. A small amount of sweet 

 sirup will be obtained, but it is not always palatable since it contains 

 mineral substances and other constituents as well as sugar. 



PRESERVING BY STERILIZATION— CANNING. 



In ordinary sweet preserves the heat of cooking may increase their 

 keeping qualities by killing some or all of the microorganisms pres- 

 ent in the raw material. It has been shown that such sterilization is 

 one of the reasons for cooking vegetables. It is the most important 

 factor in canning vegetables, whether in the home or in the factory. 



Prolonged or extreme heating tends to change the flavor and tex- 

 ture of foods, sometimes for the worse. The best method of canning, 

 therefore, will be the one which kills the most of the undesirable 

 microorganisms, while it occasions the least injury to the material. 

 Whatever method is used, the receptacles in which the food is put 

 must be sterilized as carefully as the food and finally closed so tightly 

 that no fresh organisms can find entrance. 



The method known as intermittent or fractional sterilization 

 usually answers all these conditions. In this method, the vegetables, 

 after blanching in boiling water, are put into jars, the rubber rings 

 and glass covers are laid on but not clamped, sterilized water is 

 added, and the jars heated to the boiling point of water for about 

 an hour; then the jars are fastened. This process is repeated with 

 clamps up 24 hours later, and again the third day. This method is 

 tedious, time consuming, and expensive, and hence not best suited 

 from a practical standpoint to the canning of cheap products, such 

 as greens, peas, okra, sweet corn, and Lima beans. It is, however, 

 considered the only thoroughly safe method under certain condi- 

 tions, such as prevail at high altitudes and in damp, warm regions, 

 and for this reason is recommended by the Department of Agricul- 



16889°— Bull. 123—16 5 



