Issue link: http://read.dmtmag.com/i/89494
WINERY of fermentation, many polysac- charides precipitate and settle to the bottom of the fermentor. The removal of polysaccharides is done with enzymes that have unique chemical reactivity to particular com- pounds. The main strategy is to use a mixture of enzymes (containing cellulase, hemi-cellulase, protease, pectinase, and/or beta-glycosidase), termed the "kitchen sink" method. These enzyme cocktails break down several different classes of polysaccharides simultaneously and for the most part are very efficient. However, beta-glycosidase enzymes cleave the glucose of anthocyanins and destabilize them. Beta-glyco- sidase enzymes are also made by yeast but are not particularly stable and have little or no effect on the sensory properties of finished wine. Another difficulty with enzymes is that they are only effective under specific pH, temperature and etha- nol conditions. Even more prob- lematic is that the quantity and composition of grape polysaccha- rides varies from season to sea- son. Empirical experimentation is required each season to determine the most effective way of remov- ing excess polysaccharides. Varying the amount of enzyme is generally a good enough solution. However, if the grapes have been infected with the Botrytis cinera fungus, the amount of type II arabinogalac- tan glycoproteins increases three- fold, while arabinogalactan is also increased by up to 25%, making it difficult to enzymatically treat. This leads to a lower filterability of the infected wine. FINING FOR ASTRINGENCY To understand how protein fining works on astringency, you must first understand that astringency is not a flavor, but a tactile sensation that arises from reduced mouth tissue lubrication. Tannins are thought to cause this delubrication by binding and precipitating with salivary pro- teins. Fining to remove tannins from wine is generally done when a wine (usually a red) is judged to be too astringent. Fining for astringency acts in a similar way to how the sensation is caused in your mouth. To reduce the astringency of a wine, you add pro- tein. Just like salivary protein, the protein added to wine coagulates with the tannin to form an insoluble complex. After time it settles to the bottom of your barrel or tank as a precipitant. Most of the available fining pro- teins are byproducts from other food industries (Table 1). PROTEIN SELECTION FOR FINING Although most protein prepara- tions for fining are mixtures, you Solutions in Wine Making Wine Master Product Collection Rack-Master® Revolutionary 2 and 4 barrel plastic barrel racks. Plastic barrels permeate oxygen like oak. Portable stainless steel wine totes. Email: sales@snydernet.com • Phone: 1-888-422-8683 • Fax: 402-465-1220 www.snydernet.com 82 VINEYARD & WINERY MANAGEMENT NOV - DEC 2012 WWW.VWM-ONLINE.COM