378 MICROBIOLOGY OF SPECIAL INDUSTRIES. 



injurious molds and bacteria. Moldy corn has long been regarded as the 

 probable cause of the disease, called pellagra, hi man. Still other carbo- 

 hydrate food stuffs require more or less care in the drying or curing, such 

 as hay and fodder in general. This is usually dried by simple exposure 

 to the air and sun until most of the water has been evaporated. Fodder 

 that has become moldy through the presence of too much moisture is a pro- 

 lific cause of trouble in horses and less frequently in cattle. The many 

 deaths due to the so-called equine cerebrospinal meningitis are suspected 

 many times to be due to the consumption of moldy hay. In localities 

 where the air is too moist or it rains so frequently as to make it difficult to 

 dry hay, curing is effected by a process of self fermentation. The hay is 

 piled in a mass while still green and undergoes a process of heating. The 

 temperature rises usually to about 70. The causes of this rise are some- 

 what uncertain, but it is probably due to the combined action of enzymes 

 and microorganisms. Just how much of this keeping quality is due to the 

 heating, how much to the loss of water, and how much to the accumula- 

 tion of products of fermentation is uncertain. In other cases, the heated 

 hay is spread out and quickly dries sufficiently so that it may be stored. 

 A certain small percentage of the nutriment of the hay is necessarily lost 

 in the development of the heat energy. 



Fruits are quite generally preserved by drying. In many instances, 

 as in peaches, apples, and berries, it is probable that enough moisture is 

 usually removed to prevent organisms from growing, but in many other 

 cases, as in the preparation of currants and raisins, the concentration of 

 the sugar and other solutes is the controlling factor. Frequently as much 

 as 30 per cent of the dried fruits is water. Fruit drying is often 

 accomplished by the heat of the sun's rays, in other cases artificial heat 

 or even hydraulic presses are used. 



Many manufactured products, particularly baker's goods, as crackers, 

 biscuits, dried yeast cakes, etc., are preserved by the elimination of water. 



Macaroni and vermicelli are prepared by forcing a thick paste of expeciaUy prepared 

 flour and water through openings of different sizes. The product is then dried in the 

 air until it is brittle and may then be kept indefinitely. 



Copra, one of the principal exports of certain of the islands of the Pacific and Indian 

 Oceans, is prepared by cutting the meat of the cocoanut into pieces and drying them in 

 the sun. From this copra, our desiccated and powdered cocoanut is prepared. 



Syrups, molasses, jellies, jams, and many other carbohydrate foods 

 are preserved through the concentration of the solutes. Many of these 



