When a wine is still in its infancy, certain products may need to be added to the must (the crushed grapes) to ensure that the wine achieves its best quality. I will discuss more of the whys and wherefores of these products as I continue my discussion of the winemaking process but I wanted to introduce them briefly first so that you would recognize them when they come along. It is very important to understand that, while these can all be added before fermentation or yeast addition, you must be very careful how you add each of these products as one can cause the other to not work. I will explain the interactions that should be considered with each individual product as I describe its use.
The very first product would be Pectic Enzymes. These enzymes are usually added at the crusher or can be poured over the grapes before crushing. I prefer to add them directly into the crushed grapes coming out of the crusher on their way to press(for whites) or fermenter(for reds). Enzymes do several things. First of all, grapes, like other fruits, have lots of pectin – very nice for making jam, but not so good in winemaking. The enzymes break down this pectin and allow the wine to clear more easily. This also makes for an easier filtration because the enzymes destroy some of the components in the wine that clog up a filter. While enzymes can be added to the pressed juice later, the sooner they are added to the grapes the more they help with the extraction of aromas and help to increase juice yields. Enzymes also work better if your grapes and/or juice is not ice cold. They will work in cold products, albeit slowly.
The professional winemaker has a plethora of enzymes that purport to do various things and extract certain characteristics from grapes and juice. The amateur winemaker generally has only one choice of enzyme sold by the local wine supply store and that would be a general pectic enzyme. Enzymes are fairly expensive but only a very small amount is needed to do the job. Depending on the type of grapes or fruit, the addition can be anywhere from 15 to 100 milliliters per ton of grapes or 40 to 300 milliliters per 1000 gallons of juice. As you can imagine, only drops are needed for say, a 5 gallon carboy. Amounts to add can vary by product type.
The next product that is often added early on is bentonite. Bentonite is a montmorillonite clay. In the United States, it is principally mined in South Dakota and Wyoming and is used to settle white juice before fermentation (For more information on clearing wines with bentonite see my earlier “Ask the Winemaker” post). You must be careful, however, as it will pull out the enzymes you put in. So, don’t mix in bentonite until the next day after pressing or, you can put the bentonite in, settle the juice, rack the juice off the bentonite, and then mix in the enzymes. From my experience, one to two pounds per 1000 gallons is enough to help settle the juice. This equates to about .5 to1.0 grams per gallon or a little less than 1/8th to 1/4th teaspoon per gallon. Using bentonite for this is not an exact science. In other words, if you don’t have a gram scale and must use household measurements, it will not hurt if you end up putting in a little more.