sulfur
An element that is extremely important in wine production. The addition of sulfur dioxide during crushing and pressing deactivates enzymes that catalyse oxidation, which leads to juice browning and modification of aromas and flavours, which is why it is often added to freshly picked grapes in the salt form of metabisulfite. (The compound is widely, often more liberally, used in the preparation of other foods and drinks, particularly in fruit juices and dried fruits).