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56 WINES&VINES July 2017 WINEMAKING PRACTICAL WINERY & VINEYARD genus Hanseniaspora (mainly Hanseniaspora uvarum teleomorph and Kloeckera apiculata) and other species of the genera Candida, Pi- chia, Kluyveromyces and Metschnikowia. These yeasts do not grow as strongly as the faculta- tive aerobic yeast S. cerevisiae under oxygen- limited fermentative conditions. Research has shown that even slight in- creases in dissolved oxygen in must can sig- nificantly increase the growth and persistence of non-Saccharomyces yeasts. 9 Several prac- tices employed during the first stages of wine- making such as pumping over, délestage or micro-oxygenation can increase O 2 concentra- tions in grape must. Oxygenation strategies in the early stages of both red and white wine fermentation will enhance the growth and impact of the native yeast species present. Controlling spoilage microbes prior to Saccharomyces dominance is very important. This is a very vulnerable phase, and smelling and tasting the must twice per day is recommended. It is also im- portant to monitor volatile acidity. Feed them well When it comes to nutrition, primarily nitrogen supplementation, there is much that we still need to learn regarding non-Saccharomyces yeasts. One thing research has shown is that the amino acid requirements of yeasts differ greatly between species. Nutrients developed for cultured wine yeast strains may, in fact, not be optimal for different non-Saccharomyces yeast strains. We do know that a certain population of yeasts are needed to complete an alcoholic fermentation. The addition of complex yeast nutrients—especially when the yeast assimi- lable nitrogen (YAN) is low—can stimulate yeast growth. Yeast nutrients that contain partially autolysed or fully inactive yeast is a good source of sterols, long-chain fatty acids, vitamins, minerals and some amino acids. Specialized products are not yet available for non-Saccharomyces yeasts, and the best option is to apply the same supplementation strategies to spontaneous fermentation as one would for an inoculated fermentation. In other words, make sure that the must is not nitrogen-limited, especially higher sugar (above 23° Brix) musts. Allow time for amino acid uptake before adding inorganic nitrogen (DAP)-containing nutrients, usually just before the end of the first third of fermentation. Proper yeast nu- trition will go a long way to minimize the risk of a stuck fermentation. Keep a lookout for new products, though; it will not be long before suppliers meet the demand and create tailored nutrients for specific species of fa- vorable non-Saccharomyces yeast for fermen- tation support. Monitor very closely Spontaneous ferments need more attention than inoculated fermentations. They require a certain level of coddling as there are more potential problems that may arise in the course of a fermentation. The most important risk is the fermentation rate slowing down and even stopping prema- turely, due to the fact that most non-Saccharo- myces yeasts are slower fermenters (compared to S. cerevisiae) and less tolerant to the inhibit- ing conditions towards the middle and final stages of alcoholic fermentation. ONLINEMARKETINGSYSTEM Wines Vines Analytics Visit winesandvines.com/OMS or call 866.453.9701 to set-up your free demo. Reach Thousands of Winery Decision Makers The Wines & Vines Online Marketing System is designed to help your business: • Increase sales • Generate winery leads • Manage clients and sales territories • Improve marketing effectiveness Hanseniaspora uvarum is is an apiculate yeast genus. UNIVERSITY OF CALIFORNIA, DAVIS, DEPARTMENT OF VITICULTURE AND ENOLOGY