Wine, clarification

Pectinase fungi pressing clarification wine, fruit juice... 

Racking is the removal of the clear wine off its settled solids (lees) after a period of natural settling. Because racking is always the slowest method of clarification, wine may require several settlings and rackings over a period of months to clarify well. Generally, natural settling and clarification will occur more quickly in smaller containers wine in barrels usually clarifies well. 

Ramifications of production of wine and related products are depicted in Eigure 1 (23). Certain operations are required, unique, and irreversible in order to produce certain types of wine, eg, oxidation for sherries. Other operations such as clarification and tartrate stabilization are similar for all wines. 

Fig. 1. An amplified outline scheme of the making of various wiaes, alternative products, by-products, and associated wastes (23). Ovals = raw materials, sources rectangles = wines hexagon = alternative products (decreasing wine yield) diamond = wastes. To avoid some complexities, eg, all the wine vinegar and all carbonic maceration are indicated as red. This is usual, but not necessarily tme. Similarly, malolactic fermentation is desired in some white wines. FW = finished wine and always involves clarification and stabilization, as in 8, 11, 12, 13, 14, 15, 33, 34, followed by 39, 41, 42. It may or may not include maturation (38) or botde age (40), as indicated for usual styles. Stillage and lees may be treated to recover potassium bitartrate as a by-product. Pomace may also yield red pigment, seed oil, seed tannin, and wine spidts as by-products. Sweet wines are the result of either arresting fermentation at an incomplete stage (by fortification, refrigeration, or other means of yeast inactivation) or addition of juice or concentrate.

Although it is sometimes encouraged in white wines, particularly barrel-fermented Chardonnay, this fermentation tends to lower fmitiness and be considered undesirable in other white wines unless acidity is too high. This is also tme for pink and light red wines. If it occurs after bottling, a gassy, cloudy wine results. In such wines, it can be avoided by careful attention to clarification or filtration sufficient to remove the bacteria, by adding SO2 at appropriate intervals as an inhibitor, or by pasteurization. 

Maturation regimes vary from as tittle change as possible in many white and pink wines (stainless steel tanks, cool storage, minimum time) to considerable modification in red table and a few white table wines. Fermentation and storage in fairly new 200-L barrels for about 6 mo is not uncommon for Chardoimay and white Burgundy wines. Many robust red table wines such as those from Cabernet Sauvignon grapes are often stored similarly, after fermentation and initial clarification, for up to about 3 yr in such barrels. 

Oliva, J., Paya, P., Camara, M. A. and Barba, A. 2007. Removal of famoxadone, fluquinconazole and trifloxystrobin residues in red wines Effects of clarification and filtration processes. Journal of Environmental Science and Elealth, Part B 42 775-781. 

Wine and beer industry Polyphenols can alter color and flavor of products such as wines. There are many aggressive ways of removing polyphenolic compounds, such as using polyvinylpolypyrrolidone (PVPP) or sulfur dioxide. However, polyphenol removal should be selective to avoid the undesirable alteration of the wine s organoleptic characteristics. For this reason, one option is to use laccases that polymerize the polyphenolic compounds during the wine-making process and then to remove these polymers by clarification (Morozova and others 2007). Several papers have reported that laccase is able to remove undesirable polyphenols and produce stable wines with a good flavor. 

Pectinases and (3-glucanases are the only enzymes allowed in wine-making by European legislation. They are used as clarification and filtration agents and also to release aroma compounds that are mostly present in grape as nonvolatile glycosidic precursors. Pectolytic enzymes are also reported to increase extraction of phenolic compounds and wine color... 

Uses.—The more common kinds of isinglass, especially the coarse Brazilian, are used by brewers for fining beer, and have been noticed in their application for that purpose. They are also employed for the clarification of wines, and various other liquids. 

In cold pressing pulp for white wines, present practices vary considerably within the industry. Some processors using continuous presses have found it an advantage to treat pulp with pectolytic enzymes prior to pressing. However, with the Willmes press, cold pulp to which cellulose fibers have been added press with no difficulty, and juice yields have been considered satisfactory. A general practice has been to add pectolytic enzymes to white must before yeast inoculation as an aid to rapid clarification of the new wine. 

---