Organic natural substances (proteins), which are composed of amino acids and are a main component of all living things. In grape seeds they are contained in the pulp of the grape, in dry years more proteins are formed. During fermentation they serve as food for the yeasts. In larger quantities the so-called thermolabile protein causes veil-like, grey turbidity and is removed by means of bentonite. Various protein-containing agents are used to fining and clarifying the wine, including albumin, egg white, gelatine, Hausenblase, lysozyme and casein. All these substances are positively charged electrically and therefore attract negatively charged substances.