destemming, the winemaking process of removing the stems, or stalks, from clusters of grape berries. Known as égrappage or éraflage in French, it usually takes place immediately after and combined with the crushing operation. Grape stems, and the attached brush of pulp, contain tannins. If they are crushed or broken, these can be leached into the wine during fermentation, making the wine taste bitter and astringent. Destemming also very slightly increases the resultant colour and alcoholic strength because stems, if included, have a dilution effect. Fermentation is also likely to be slightly slower and cooler since including stems increases the interfaces between the fermenting must and air, or oxygen.