These chemicals are the most commonly used in winemaking, along with pectin enzymes. Also known as sulfur dioxide (S02) it is used for several purposes. Prior to a pulp fermentation S02 is used to stun any wild yeasts that are present so that an added wine yeast cane take over and colonize without opposition or competition. At this same time it is used to control bacterial infection and oxidization of a wine must. Home vintners will find good use of S02 to keep their musts sterile prior to fermentation. Sulfur Dioxide is commonly use throughout fermentation to prevent excessive oxidization of juice and wine during periods of exposure to air. This is accomplished because S02 consumes oxygen and then converts it to sulfuric acid.
There is not substitute for this compound in winemaking, and most all winemakers will need its use sooner or later. Keeping your wine air locked with minimized contact with air, will allow you to keep lower levels of S02 present in your wines. Commonly 50 ppm are added pre fermentation. I find this amount to high!! this is about 1/4 tsp per 5 gallons of wine, or 5 campden tablets. I rarely use no more that 15 to 20 ppm in my juice or must, 1/8 tsp. because my fermentations are always done under tight air lock. a gentle stirring every 3 days or so will give the yeast all the air they need, without exposing your must to unnecessary oxygen. Cost is very inexpensive and S02 is readily available at wine and beer supply shops.
Pectin is found in most all fruit, It is the element that is use for making jams and jellies, but is known to cause a hazy looking wine if left unchecked. It will stay in suspension indefinitely and will keep a new wine looking cloudy. Pectin Enzymes are enzymes that eat pectin, thus eliminating the hazing problem that it will cause. The enzyme is very inexpensive, and should be used in ALL batches of wine. Adding do a grape wine, or even a wine kit is not uncommon. The usual dosage will be about 5 or 6 drops per gallon of wine must, or 20 drops or so for 5 gallons. It is added prior to fermentation.
Carbonates are used in winemaking to reduce the acidity of a must or wine.
Uses as a stabilizing compound to prevent fermentation of residual sugars in wine