Finings

Finings are substances that are usually added at or near the completion of the processing of brewing wine, beer, and various nonalcoholic juice beverages. Their purpose is for removal of organic compounds; either to improve clarity or adjust flavor/aroma. Specifically, the removed compounds may be sulfides, proteins, polyphenols, benzenoids, or copper ions. Unless they form a stable bottom sediment in the final container, the spent finings are usually discarded from the beverage along with the target compounds that they capture.

Historically, various substances such as egg whites, blood, milk, isinglass, and Irish moss have been used as finings. These are still used by some producers, but more modern substances have also been introduced and are more widely used, including bentonite, gelatin, casein, carrageenan, alginate, diatomaceous earth, pectinase, pectolyase, PVPP (Polyclar), kieselsol (colloidal silica), copper sulfate, dried albumen, hydrated yeast, and activated carbon.

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Clarification and stabilization of wine

In winemaking, clarification and stabilization are the processes by which insoluble matter suspended in the wine is removed before bottling. This matter may include dead yeast cells (lees), bacteria, tartrates, proteins, pectins, various tannins and other phenolic compounds, as well as pieces of grape skin, pulp, stems and gums. Clarification and stabilization may involve fining, filtration, centrifugation, flotation, refrigeration, pasteurization, and/or barrel maturation and racking.

Clarifying wine

In wine tasting, a wine is considered "clear" when there are no visible particles suspended in the liquid and, especially in the case of white wines, when there is some degree of transparency. A wine with too much suspended matter will appear cloudy and dull, even if its aroma and flavor are unaffected; wines therefore generally undergo some kind of clarification.

Before fermentation, pectin-splitting enzymes and, for white wine, fining agents such as bentonite may be added to the must in order to promote the agglomeration and settling of colloids later. Pectins are structural molecules in the cell walls of fruits which have the important function of 'gumming' plant cells together. The pectin content of grapes increases steadily throughout ripening, reaching levels of about 1 g/l, although it varies by varietal and pre-fermentation handling processes. Large pectin molecules can affect the amount of juice yielded at pressing, ease of filtration and clarification, and extraction of tannins. Grapes contain natural pectolytic enzymes responsible for softening the grape berries during ripening, but these are not active under wine-making conditions (due to pH level, SO₂, and alcohol.) Therefore, fungal pectolytic enzymes are often added to white must to break up pectins, decrease the viscosity of the juice, and speed up settling. In red musts, this increases color and tannin extraction.