Sulfur Dioxides in Wine and Vinegar Making

Sulfur Dioxide in Wine and Vinegar Making 

The selected strain of yeast is trained to ferment in a starter containing a very small amount of SO2 when the fermentation of the starter is in full progress, it is mixed with further quantities of must containing progressively increasing amounts of SO2. The yeasts in the starter thus become S02-resistant and can be employed for the fermentation of the bulk of the must, to which a fair amount of SO2 has been added, and in which no microorganisms or undesirable yeast, other than the selected strain which has become S02-resistant, will develop. 

Bioletti and Cruess (1912) did not believe that culture yeasts were acclimatized to SO 2 on the contrary, they favored postponing their addition to a sulfited must until after the full effect of the maximum amount of free SO 2 was exerted on the undesirable organisms and when the yeast starter was exposed only to the minimum amount of free SO2. 

Sulfur dioxide is also used in wine making for the most important operation known as the defecation of must. It is customary when making white wines to allow the must to clear by settling before fermentation, and then to draw off the supernatant clear must into the fermentation vats. The use of sulfur dioxide in this process, which may last from two to three days, is beneficial in several ways  

It delays the free fermentation of the must until after it has cleared, 

---

VIII. Sulfur Dioxide in Wine and Vinegar Making. 136... 

---