STALK: Stalks hold grapes in a bunch. They weigh around 3-7% of the total weight of the harvest depending on the type of vine. Stalks contain tannins, which are soluble in alcohol. Tannin contributes the following qualities to wine: Astringency maintains quality and helps in coagulation with fining agent containing protein that is used during the clarification process.

SKIN: It is natural cover to protect the contents inside the grape. The skin contains the pigments “anthocyanes” and “flavones” that give colour to the wine. The skin is covered with a waxy substance called bloom which contains bacteria, moulds, and millions of wild and wine yeasts including Saccharomyces ellipsodium in various forms which convert the grape sugar to alcohol.

PULP: It is a soft substance behind the skin of the grapes which contains liquid, sugar (glucose and fructose), and acids, such as tartaric, malic and citric acids. It amounts to 80-85% of the weight of the bunch. During the fermentation process, these acids interact with the alcohol and produce ‘easter’ which provide bouquet to the wine. The water content of the pulp is about 80% and the sugar is between 10-25% and the rest is acids.

PIPS: These are the small seeds or grapes. These contain both tannins and oils. They give an unpleasantly bitter flavor to the wine and are discarded during wine making.