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80 W i n e s & V i n e s D e C e M b e r 2 0 1 4 N/L. Most commercial nutri- ent products, including DAP (diammonium phosphate), have documented quantities of nitro- gen that each of their products contributes based on standard addition rates. Many wineries may opt to only add a rehydration nutri- ent such as GoFerm and make DAP additions, as this was encouraged when research on nutrient management was initi- ated. However, recent research indicates that reliance on DAP may not suffice in addressing nutrient needs for some fer- mentations. Furthermore, some evidence indicates that larger DAP additions, without complex nutrient additions, may simplify the aroma and flavor compo- nent of the wine by the end of fermentation. It should be emphasized that DAP should never be added with yeast hydration, as it is toxic to the yeast and can inhibit primary fermentation from starting properly. Yeast hydration nutrients such as GoFerm or Nutriferm should be used for each inoculation, and complex nutrients like Fermaid k or complimentary products can be added prior to the use of DAP after primary fermentation has started. DAP is recommended to obtain that minimum YAN value when the yeast hydration nutrient and complex nutrient are not enough to reach the critical minimum. Although DAP is less expensive than many com- plex nutrients, it only contains ammonium, the inorganic form of nitrogen. Conclusion Research on YAN and its rela- tionship with hybrid or native varieties is ongoing, especially in the Mid-Atlantic region. While following adequate nu- trient strategies is not a 100% guarantee against hydrogen sulfide production, measuring YAN, understanding nutrient additions and adequately feeding the yeast during fer- mentation can minimize H 2 S production in the winery. While this task may seem overwhelming at first, espe- cially during the harvest sea- son, many wineries have found taking this preventative step to be less time consuming and better for wine quality than dealing with copper additions, copper trials or potentially not being able to adequately fix reductive wines. wE WineEast Winemaking EASTERN WINE LABS Serving the Analytical needs of East Coast Wineries WWW.EASTERNWINELABS.COM Ph 609-859-4302 Cell 609-668-2854 chemist@easternwinelabs.com AOAC Member EasternWineLab_Mar09.qxp 1/22/09 9:47 AM Page 1 Case By Case Wine and Grape Supplier Your Source for World Class Wine Grapes and Bulk Wines Serving wineries nationwide on a Case By Case basis East and West Coast varieties available: R Winegrapes R Bulk Wine R Juice R Shiners Jim, Owner Northern California Office (707) 671-4126 • jim@casebycasebrokers.com Tom, Domestic and International Sales Southeast Office (864) 401-2297 • tom@casebycasebrokers.com www.casebycasebrokers.com The excess amount of available nutrients in high-YAN must can cause fermentation to proceed quickly and create winemaking challenges. DENISE GARDNER