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58 P R A C T I C A L W I N E R Y & V I N E YA R D June 2015 W I N E M A K I N G The wine industry has trusted Kennedy/Jenks Consultants for professional environmental engineering services since the 1950s. We specialize in providing cost-saving, sustainable solutions to meet winery needs. Wastewater Water Supply Storm Water Solid Waste Facility Planning Design Construction Management Hazardous Materials Water/Energy Audits Air Emissions and Odors Regulatory Compliance Land-Use Permitting/CEQA e: BobChrobak@KennedyJenks.com t: 415.243.2150 www.KennedyJenks.com/wine OUR SERviCES inCLUDE: • Climate Controlled Bonded Wine Storage Facility • Cased Goods, Full Barrels, and Dry Goods • Centrally located in Paso Robles • Unix Inventory System Trucking, Harvesting and Warehousing Available! 3230 Riverside Ave, Ste # 150 Paso Robles, CA 93446 Phone (805) 237-9499 Fax (805) 237-9599 MichaelDusiWarehouse_Dir07 10/25/06 11:49 AM Page 1 SUPPORT RESEARCH & WINE INDUSTRY NEEDS THROUGH THE A M E R I C A N V I N E YA R D FO U N D AT I O N P.O. Box 5779, Napa, CA, 94581 • T: (707) 252-6911 Visit our Web site at www.avf.org for information on funding and current research projects A S S E S S M E NTS O F D I F F I C U LT TO F E R M E NT J U I C E S Dr. Linda Bisson examined the causes of chronically difficult to ferment juices. These problem fermentations do not appear to respond to nitrogen or other commercial nutrient addition, occur regardless of yeast strain used, and are challenging to restart the fermentation. For more information visit AVF.org or contact Dr. Bisson at lfbisson@ucdavis.edu. For a wealth of useful viticulture and enology research and information, visit AVF.org, ngr.ucdavis.edu, asev.org, iv.ucdavis.edu or ngwi.org Finding Solutions Through Research We plated samples obtained from three wineries and were unable to recover any viable lactobacilli or pediococci. However, four atypical strains of acetic acid bac- teria were present in all three cases that persisted into the wine. We identified these acetic acid bacteria as: Acetobacter orientalis, Acetobacter ghanensis, Acetobacter malorum and Gluconobacter cerinus. Although these bacteria have been found in wine before, they are rare and not usually found at the levels at which we are seeing them on fruit or in the resulting wines. These bacteria are com- monly isolated from other types of fruit and plant material or are associated with fruit flies. The factors leading to a bloom of these species over the more common acetic acid bacteria found on the surface of grapes are unknown. The volatile acidity levels in the wines are not as high as they would be with Acetobacter aceti, remaining below the legal limit, and the winemakers do not observe any films forming on the wines. Also, according to the winemakers, addi- tional supplementation with SO 2 does not resolve the issues in these fermentations, suggesting that either SO 2 inhibited the bacteria but the yeast inhibitor was pro- duced prior in the fermentation or that these bacteria are more resistant to SO 2 than is typical of acetic acid bacteria. Novel mechanics of inhibition by lactic acid bacteria We have also confirmed the inhibitory role of previously identified lactic acid bacteria in yeast fermentation, which