230 Report of State Board of Horticulture. 



and inducing some unscrupulous persons to use injurious preservatives to 

 cheapen the cost of manufacture. It is well known that pure must is 

 healthful and nutritious, but with the addition of chemical preservatives 

 it becomes injurious in proportion to the amount and kind of preservative 

 used. 



COMPOSITION OF THE GRAPE. 



The grape contains fifteen to thirty-five per cent of sugar (Balling's 

 scale), about two to three per cent of nitrogenous substances, and some 

 tartaric and malic acids. The skin contains tannin, cream of tartar, and 

 coloring matter. The seeds contain tannin, amylaceous matters, and fat. 

 The stems contain tannin, divers acids, and mucilaginous matter. The 

 comparative composition of the different parts of the fruit determines the 

 value of must made from any grape. 



CAUSES OF FERMENTATION. 



It is well known that grapes and other fruits when ripe have the invisi- 

 ble spores of various fungi, yeast (ferments), and bacteria adhering to 

 them. When dry these are inert, but after the grapes are crushed and they 

 are surrounded by the must they become active and begin to multiply. 

 If the must is warm, the changes take place rapidly; if, on the other hand, 

 it is cool, the change is slower. But in either case, if left alone, the 

 organisms increase until the must ferments, 'ine most favorable temper- 

 ature for fermentation is between sixty-five and eighty-eight degrees 

 Fahrenheit. Cold checks, but does not kill, the ferment. This fermenta- 

 tion, now commonly called the elliptic yeast, changes the sugar in the 

 grape to alcohol and carbonic acid gas, and is the leading factor in con- 

 verting must into wine; hence it will be readily seen that to keep unfer- 

 mented must sweet, fermentation must be prevented, and to be salable 

 the product must be clear, bright, and attractive. 



METHODS OF PREVENTING FERMENTATION. 



Fermentation can be prevented in either of two ways: 



(1) By chemical methods, which consist in the addition of germ poisons 

 or antiseptics, which either kill the germs or prevent their growth. Of 

 these, the principal ones used are salicylic, sulphurous, boracic, and 

 benzoic acids, formalin, fluorides, and saccharin. As these substances are 

 generally regarded as adulterants and injurious, they should not be used. 



(2) Mechanical means are sometimes employed. The germs are either 

 removed by some mechanical means, such as a filtering or a centrifugal 

 apparatus, or they are destroyed by heat, electricity, etc. Of these, heat 

 has so far been the most practical. 



When a liquid is heated to a sufficiently high temperature all organisms 

 in it are killed. The degree of heat required, however, differs not only 

 with the particular variety of organisms, but also with the liquid in 

 which they are held. Time is also a factor. An organism may not be 

 killed if heated to a high temperature and quickly cooled. If, however, 

 the temperature is kept at the same high degree for some time, it will 



