The process of fermentation in winemaking turns grape juice into an alcoholic beverage. Yeasts transform sugars present in the juice into ethanol and carbon dioxide. Knob Hall Winery uses steel tanks for our fermentation process which differs from whites to reds. And last year we harvested about 80 tons of grapes.
We ’field dress’ (or clean) the grapes in our vineyard. They are then weighed and taken to the press which is a large air bladder that presses the grapes. Juice flows out of the press into a pan beneath it. The juice is then pumped to a tank where it settles and is usually cooled for a day or so. When the winemaker wants to start fermentation, she heats up the tank and adds yeast.
We bring the red grapes in and sort them on a table. Up to eight employees stand for hours discarding bugs, leaves, or anything else that shouldn’t go in the wine. (This is the difference between us and “bulk wine” companies who mechanically harvest hundreds their grapes. All wine juice is white. Red wine gets its color, and tannins, (a textural element that makes wine taste dry), from contacts with skins and seeds. Growing grapes on the East Coast, we sometimes have issues getting the seeds ripe. If the seeds are not ripe and they are pumped, they can be injured and give off a herbaceous smell and taste. For that reason, we do not pump red grapes, but rather, we gravity feed them into our tanks. While the juice, skins, and seeds are falling into the tank, we’re drawing off some of the juice at the bottom. This is called a Saignée (French for bleeding), and this process concentrates the juice that remains in the tank and the juice that is taken off is fermented into Rosé. Both white and red wines finish their initial fermentations by the end of the year. The red wine is usually then put into barrels where they will stay for 6 – 18 months, depending upon the type of wine they’ll make. Rosé and white wine is chilled in order to make the wine “cold stabilized”. This allows the wine to be chilled in the refrigerator without developing ‘wine diamonds’, which are harmless but produce “floaters” in wine.
As always, we invite you to tour our vineyard (weather permitting), or watch the winemaking process. Give us a call at 301-842-2777 to schedule a tour!