Grape processing techniques Important families of phenolic compounds in grapes and wine Anthocyanins (red color); Tannins (provide bitterness, astringency and mouth feel); Flavonols (co-factors for co-pigmentation). Location of phenols Skin Pulp Seed Anthocyanins Hydroxycinnamic acid Tannins Tannins Hydroxybenzoic acid Flavonols Winemaking flowchart Crushing = grapes are usually crushed with a mechanical crusher in order to liberate the juice before fermentation. Destemming = removal of grapes from the stems or more usually removal of the stems from crushed grapes. Fermentation = decomposition of organic substances by enzymes often with release of carbon dioxide and production of alcohols, acids and other reaction products. Racking = drawing off the wine from the marc towards the end of fermentation in vats. Marcs = the solids of grapes consisting mainly of skins and seeds which are left in the fermenters after devatting and then pressed. Pumping over = pumping fermenting must from the bottom of a fermenter to the top of the same fermenter to aerate the must by pumping the must over the cap to mix the content of the vat. Defecation = holding must or wine in a vessel until the solid matter has deposited. The term is applied mainly to the clearing of the musts before fermenting for white wines. Punching the cap = Pushing the cap below the surface of the liquid with a rammer during fermentation. Stabilization = Treating wine to enable it to withstand cold, heat and exposure to light without becoming dull or cloudy. Must = unfermented grape juice. Wine= made by partial or complete fermentation of grape juice. Malolactic fermentation= decomposition of the mailc acid in wine to lactic acid and carbon dioxide by bacteria.