10 MANUFACTURE AND PRESERVATION OF GRAPE MUST. 



Of late years extended efforts have been made to keep the must 

 unfermented and put it up in such shape that it can be used anywhere 

 and at all times of the year. 



Until recently the use of must was almost exclusively restricted to 

 medicinal purposes. Unrestricted use has been delayed on account 

 of a lack of special knowledge underlying the principles of the process 

 of manufacture and of skill in their application, resulting- in many 

 failures, thus making the production of a good article uncertain and 

 very expensive, and inducing some unscrupulous persons to use injuri- 

 ous 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 15 to 35 per cent of sugar (Balling's scale), about 

 2 to 3 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 compara- 

 tive 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 

 invisible spores of various fungi, yeast (ferments), and bacteria adher- 

 ing 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 rap- 

 idly; 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 fer- 

 ments. The most favorable temperature for fermentation is between 

 65 c and 88° F. Cold checks, but does not kill, the ferment. This fer- 

 mentation, now commonly called the elliptic yeast, changes the sugar 

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

 in converting must into wine; hence it will be readily seen that to keep 

 unfermented 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 poi- 

 sons or antiseptics, which either kill thegerms or prevent their growth. 

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

 and benzoic arid-, formalin, fluorides, and saccharin. As these sub- 



