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84 WINES&VINES April 2016 WINEMAKING WINE EAST and flavor compounds) in the early stages of fermentation. In fact, mixed microbial colo- nies are quite literally death matches, with each species bat- tling for limited nutritional re- sources and using all possible weapons to stunt the growth of all others. Defensive actions can in- clude the release of targeted tox- ins (as with the infamous "killer yeasts"), organic acids or fatty acids and enzymes that, by happy coincidence, increase the variety and concentration of aroma com- pounds in wine. Non-saccharomyces strains produce different acids and more enzymes (esterases, glycosidases, β-glucosidases, proteases, etc.) than most S. cerevisiae, producing different aromatic profiles and potentially enhancing mouthfeel. In most cases, the high ethanol tolerance and anaerobic capabil- ity of S. cerevisiae strains leaves them as final victors in the fer- mentation battle, though some other species (such as Torulaspora and Pichia) are occasionally able to survive to the bitter end. While it's important to note that bacte- ria—both desirable and spoil- age—also play a role in microbial interactions, the influence of vari- ous environmental factors on bacterial communities in grapes and wine is currently understud- ied and poorly understood. Yeast assimilable nitrogen Nitrogen management is another major challenge for winemakers conducting spontaneous fermen- tations. Existing research has es- tablished rough guidelines for yeast assimilable nitrogen (YAN) concentration for a number of commercial yeast strains and ini- tial Brix levels, but the variables governing YAN requirements are poorly understood. In spontane- ous fermentations, the mix of microorganisms is generally un- known, making the prediction of nutritional needs difficult. N o n - S a c c h a r o m y c e s y e a s t strains may cripple S. cerevisiae by depleting individual amino acids early in fermentation, and Toru- laspora delbrueckii has been re- p o r t e d t o e x h a u s t n i t r o g e n supplies in the first 48 hours. On the other hand, the early death and autolysis of some short-lived non-Saccharomyces yeasts, and the proteolytic action of others, may increase the pool of nutrients available for S. cerevisiae during mid- to late-stage fermentation. (After alcoholic fermentation, the subsequent death and autolysis of S. cerevisiae provides nutrients for spoilage organisms if appropriate preventative steps aren't taken.) Some producers argue that in- digenous YAN concentration is another feature of terroir. Though that point is debatable, it is certain that the sheer number of variables impacting nitrogen consumption in spontaneous fermentation makes nutritional requirements hard to predict and manage. Grape Juice for Winemaking • California • Italy • Chile • South Africa Bulk Wine— CA North Coast • Drums • Totes • Tankers CFP Winemakers Fruit Juice for Winemaking • Year-around availability • 15 varieties Wine Grapes • California • Chile • South Africa Logistic Solutions • Coast to Coast CFP Winemakers, Pittsbugh PA www.cfpwinemakers.com • 412-232-4507 Trellis Supplies • Notched Metal Post, Wood • Anchors • Wire • Tools • Gripples • Dura-Line Training & Tying Supplies •Tree-fix • Wire ties • AgLoc • Klip-on • Grow Tubes • Training Stakes • Tying Products Wildlife Control • Bird netting • Side Applied Netting • BirdGard • Scare Devices • Deer Fence & Deterrents Spring Pruning and Tying Supplies FINGER LAKES TRELLIS SUPPLY BUY ONLINE! www.fingerlakestrellissupply.com 315-904-4007 4041A Railroad Ave. info@fingerlakestrellissupply.com Williamson, NY 14589 A dilution plating is performed to identify the number and types of yeast present in fermenting juice at the onset of Riesling fermentation.