In wine making, campden tablets are used to keep the wine from spoiling after it has been bottled. Thus, you typically add one tablet per gallon of wine 24 hours prior to adding the wine yeast (before fermentation begins). By doing this, you can sterilize the juice to ensure quality and consistency of flavor during fermentation. This is especially important if you are using fresh fruit to make your wine. Many wine makers also crush up and add one tablet per gallon just before bottling. This helps to prevent growth of mold, harmful bacteria, and wild yeast.
What they can do for equipment
Another great use of campden tablets is for sanitizing wine making equipment. By mixing them with water, you can create a sanitizing solution that is useful for cleaning fermenters, air-lock, stirring spoons, hoses, and other equipment that is exposed to wine must!
Campden tablet limitations
While these tablets are excellent for cleaning, as well as halting fermentation for a period of time, the fermentation pausing qualities will not last forever! Eventually, the fermentation will overcome the effects of the tablets. Additionally, be careful about using too much sodium metabisulfite, as it can affect the flavor of the wine.