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36 WINES&VINES June 2018 WINEMAKING PRACTICAL WINERY & VINEYARD somewhat reactive with anthocyanins but are quite expensive. Laffort has patented a process to produce highly reactive catechin tannins. 6 The resulting commercial product, Tanin VR Color, has an approximately 10-fold higher re- activity than grape skin tannin products and an approximately 100-fold higher reactivity than standard fermentation tannin products, greatly facilitating stabilization of color in red wines. The use of enological tannins is also recom- mended in the case of botrytis infection to minimize the oxidative browning caused by laccase (for more information, please review the website: awri.com.au.). Tannins bind to protein surfaces and can inhibit enzymatic activity, including that of laccase at concentra- tions less than it takes to actually facilitate precipitation and removal. Enzyme and tannin application criteria and potential benefits Enological enzymes and tannins are not neces- sarily meant to be used in a formulaic or recipe fashion. There are specific circumstances where their use is most beneficial, as well as some stylistic goals that may necessitate con- sistent use. The first consideration is the quality and condition of the fruit. Enzymes can certainly aid in extraction of fruit that is picked before optimal ripeness due to vineyard conditions, while mold pressure may indicate early tannin application with minimal pre-fermentation extraction either by maceration or enzyme application. When fruit conditions do not in- dicate an early enzyme application, an addition of a pectinase/beta-glucanase enzyme blend after pressing off the skins will help with wine clarity and filterability and will lower the mi- crobial load in the resulting wine. When using gentle cap-management tech- niques, an enzyme application can help the wine reach optimal color and tannin potential. In challenged vineyards or difficult vintages, where color and/or tannin is underdeveloped, enzyme extraction and tannin stabilization can be used to maximize these wine quality param- eters. Selective extraction of wine quality components such as color, soft grape skin tan- nins and aroma precursors can be achieved by the proper enzyme selection and application. Grape varieties that are high in soluble proteins when crushed are particularly good candidates for a sacrificial tannin addition at the crusher. Soluble proteins as well as cell- surface-bound proteins can bind and sequester the valuable grape skin tannins that extract early in the aqueous phase upon grape crush- ing. The application of enological tannins strong in protein-binding can help in preserva- tion of the native grape skin tannins by occupy- ing the protein surface tannin-binding sites present in the must. Enological tannin addition can also help to fill in the structure and body of a wine. An early addition of tannin can allow for benefi- cial integration of the added tannin into the desirable oligomeric polyphenolic structures. In fruit that may be low in tannin, supplemen- tation can fill in gaps in the structure that would otherwise compromise wine quality. As another tool in balancing the structure of chal- lenged vintages, the availability of selective fining agents can work with enological tannin additions to achieve the balance sought. Use of enological tannins is also indicated when fruit is compromised by mold or mildew. Tannins can react with mold proteins that give a musty character to wines and remove them, as well as neutralizing a portion of the laccase activity that many molds produce, causing rapid and excessive oxidation of phenolics and resulting in color degradation and loss. High ellagic tannin products are generally good protein-binding options. The benefits of enological enzyme and tan- nin application are plentiful. Proper selection and addition can maximize stable color and tannin, aid in building structure and assist in bringing flavor and aroma consistency across variable vintages. The addition of enological enzymes and tannins can be integrated into almost any existing maceration, fermentation and style differentiation or aging strategy. Regarding the addition of enological en- zymes and tannins with existing flash détente technology: The rapid extraction possible with flash technology almost necessitates the use of exogenous agents to balance and stabilize the resulting must and wine. Consult with a flash technology provider and enological product supplier for optimal product offerings and applications. Case study: Optimization of color and tannin in Merlot In this collaboration between Delicato Family Vineyards, Fresno State University and Laffort USA, Merlot fruit from the San Bernabe Vine- yard in King City was donated by Delicato to Fresno State for use in a student-based trial of enological enzyme and tannin applications for the purpose of improving color and tannin ex- traction and stabilization in the finished wine. Laffort USA provided all enological products and assisted the Fresno State Winery in techni- cal guidance of the student winemakers. The trial was set up with three lots: a con- trol of standard practice with no enzyme or tannin additions; one treatment of standard Figure 7. Bar graph illustrations of the increase in color and tannin in enzyme-tannin treated wines versus control from 6 to 12 months in the first year of cellar/barrel aging. The percent reduction versus control over the same STABILIZATION AND RETENTION OF COLOR AND TANNIN Figure 7. Bar graph illustrations of the increase in color and tannin in enzyme-tannin treated wines versus control from 6 to 12 months in the first year of cellar/barrel aging. The percent reduction versus control over the same STABILIZATION AND RETENTION OF COLOR AND TANNIN Bar graph illustrations of the increase in color and tannin in enzyme-tannin treated wines versus control from 6 to 12 months in the first year of cellar/barrel aging. The percent reduction versus control over the same time period shows less losses of both color and tannin. STABILIZATION AND RETENTION OF COLOR AND TANNIN Color Extraction and Stabilization Tannin Extraction and Stabilization 6 months 12 months 6 mo. vs. 12 mo. 6 months 12 months 6 mo. vs. 12 mo.