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34 WINES&VINES June 2018 WINEMAKING PRACTICAL WINERY & VINEYARD E nological tannins and enzymes are powerful winemaking tools. Proper use can improve the basic characteristics of a wine, from increasing the depth of color to imparting fuller and more supple tannins to the final wine. Other, subtler process improvements include better filtration, protec- tion from oxidation and microbial control. Enological enzymes Commercial enzymes are now accepted by many as an integral part of winemaking. With many suppliers offering a vast array of enzymes under different brand names, the choice avail- able to winemakers is staggering. Some view enzymes as commodity products to be pur- chased on price alone. However, significant differences in quality exist between supplier offerings. A good understanding of enzymes and their specific role in winemaking applications is necessary to make informed decisions. The main substrate target for enological enzyme applications in red winemaking is grape pectin (see Pectin Polymer Showing Structural Components and Sites of Enzyme Activity, above). Pectin, cellulose and hemicel- lulose are structural polysaccharides in the middle lamella and primary cell walls of grape cells. 3 Red grape skins contain approximately 75% more cell wall tissue than grape pulp does. 10 Cell wall polysaccharide structure changes with grape ripening due to increasing activity of the grape's own pectinases. Pectinases liberated from the grapes them- selves, however, are not very active under winemaking conditions. 2 Commercial pectin- ase-based enzyme preparations derived from Aspergillus species are commonly used in red winemaking to enhance color and tannin ex- traction, to improve yield and to aid in clarifi- cation and filtration. 3 The predominant enzyme activity in wine- making enzyme products is pectinase, which sounds simple. The problem is that pectinase is not one enzyme; it is actually a suite of many enzyme activities. The composition and pro- portion of those specific enzyme activities can change the appropriate optimal enzyme ap- plication. The main enzyme activities in a commercial pectinase are pectin lyase, pectin methyl-esterase and polygalacturonase. Sec- ondary pectinase enzyme activities also con- tribute to the overall activity and can determine the optimal application. Enzyme and Tannin Applications Potential impacts on red wine quality By Peter Salamone and Shaun Richardson COOCH OH OH OH OH O Methylated galacturonic acid Polygalacturonase OH OH OH OH O Galacturonic acid Pectin lyase Pectin methyl esterase Pectin main chain Pectin side chains Pectinase enzyme activity in red winegrape processing is targeted towards degradation of the main backbone of the pectin molecule. The concerted activity of pectin lyase, pectin methyl-esterase and polygalacturonase break the main rhamnose-galacturonic acid chain resulting in enhanced extraction of both tannin and colored anthocyanin molecules. PECTIN POLYMER SHOWING STRUCTURAL COMPONENTS AND SITES OF ENZYME ACTIVITY