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68 p r a c t i c a l w i n e r y & v i n e ya r d a U G U S t 2 0 1 4 W I N E M A K I N G ScareWindmill To birds windmill looks like a flock of birds taking off in fright. New improved lock system to keep blades from coming loose. 36" dia. blades that repel birds in one or more acre area. Effective for birds in vineyards, fruit trees, and blueberries. Effective on wild turkeys & geese too 30 day unconditional money back guaran- tee. $89 JWB Marketing (800) 555-9634 birddamage.com Figure 3. The aromatic index of 4MMP in wines from a Sauvignon Blanc must treated with A) PVPP + Ca bentonite + Isinglass (600 ppm), B) pea protein + PVPP (400 ppm), C) pea protein + Ca bentonite (400 ppm) and D) potato protein (150 ppm), respectively. Figure 4. Volatile thiol concentrations of a 2012 Sauvignon Blanc comparing a traditional rehydration product with a new formulation of a rehydration product. (Aromatic index: con- centration of the aroma compound in the wine, divided by its sensory threshold.) Figure 2. Glutathione concentration (mg/L) of wines from a Sauvignon Blanc must treated with A) PVPP + Ca bentonite + Isinglass (600 ppm), B) pea protein + PVPP (400 ppm), C) pea protein + Ca bentonite (400 ppm) and D) potato protein (150 ppm), respectively. plays an important role in acetate ester production. Adequate amounts of pantothenate are therefore necessary for wine aroma opti- mization. The use of an organic nutrient rich in pantothenate is advised in certain winemaking conditions. Additions of inorganic nitrogen in the form of diam- monium phosphate (DAP) or complex nutritional products made from yeast- derived components as well as DAP addition have been shown to relieve some yeast metabolic stress that can lead to sulfur compound production. The important fact is that more is not always better. Extensive DAP additions during fermentation can have negative effects on wine aroma since nitrogen defi- ciency is not the only cause of negative sulfur-compound production. Aroma protection : the glutathione factor Wine aroma can change significantly dur- ing aging. The positive aromas often diminish, and negative aromas may start to form. Aroma compounds that diminish first are those most susceptible to oxida- tion. The volatile thiols of Sauvignon Blanc are examples of aroma compounds that rapidly decrease with aging. A recent approach to wine aroma pres- ervation involves the use of glutathione. Glutathione is a powerful antioxidant with a very high redox potential (even higher than ascorbic acid), which occurs naturally in grapes. It protects 4MMP, 3MH and 3MHA against oxidation by binding to quinines, which are an oxi- dized form of diphenols. For example, the addition of 10 mg/L pure glutathione at bottling significantly slowed the rate of decline in wine aroma and the yellowing of wine color. It also reduced the formation of aging aromas