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November 2015 WINES&VINES 125 WINE EAST WINEMAKING with more volatile thiols than other strains. However, it is known that an enzyme (β-lyase) is re- sponsible for the cleavage of the carbon-sulfur bond between the non-volatile amino acid/thiol con- jugates. As the conjugated thiols can account for 10% of the volatile thiols, increased β-lyase activity can lead to higher thiol concentra- tions in wines. Multiple studies report that yeast strains such as Levuline ALS, Zymaflore VL3, Anchor VIN 13 and Uvaferm SVG have demon- strated a remarkable ability to produce wines with high concen- trations of volatile thiols. Interest- ingly, a co-fermentation of Pichia kluyveri and Saccharomyces cere- visiae was demonstrated by Nicole Anfang to significantly increase concentrations of 3MHA in the resulting wine. Currently, CHR Hansen markets a commercial P. kluyveri strain that can be directly i n o c u l a t e d ( n o r e h y d r a t i o n needed) and followed by a S. cere- visiae strain after the consumption of about 8° Brix. Yeast nutrition The amino acid-conjugated thiols in the juice are metabolized by yeast, and the carbon-sulfur bond between the amino acid and the thiol is cleaved by an enzyme known as β-lyase. The addition of diammonium phosphate (DAP) can interfere with the pathway that regulates amino acid trans- port and, in turn, this can lead to wines with a lower volatile thiol concentration. This phenomenon is known as nitrogen catabolite repression (NCR). The use of Laffort's Dynastart, a yeast rehydration that is made of yeast autolysates and inacti- vated yeast, has been shown to lead to wines with higher concen- trations of volatile thiols than wines made from yeast rehydrated with DAP. However, both the organic and inorganic rehydration regimes had greater thiol concentrations than the control, which had no nutrient additions during fermen- tation, according to a paper by Gal Winter. 251 Gambee Road, Geneva, NY 14456 Phone: 315-759-2118 Toll free: 888-234-6752 Fax: 315-789-1848 Email: cjennings@vancemetal.com Website: www.vancemetal.com Quality Rugged 12 gauge, Custom & Stock Stainless Tanks Catwalk Systems • Pump Over Carts • Custom Hoppers, Chutes & Bins PROUDLY MADE IN THE USA 11 WAYS TO MAXIMIZE AROMATIC THIOLS E mploying the following strategies can help winemakers maximize the aromatic potential of thiol-driven varieties from harvest to bottle. 1. Harvest during cooler hours of the day. 2. Use a brief cold soak (no more than 24 hours). 3. Add 50ppm of SO 2 to the must before cold soak and pressing. 4. Maintain a relatively reductive environment at all stages (ensure adequate O 2 in must for healthy fermentation). 5. Avoid long/high-pressure cycles. 6. Choose a yeast strain known to produce high concentrations of thiols. 7. Rehydrate yeast with a complex organic rehydration nutrient. 8. Avoid or minimize the use of DAP. 9. Use fermentation temperatures around 18°-20° C. 10. Avoid copper fining. 11. Bottle under screwcap or technical cork.