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62 p r a c t i c a l w i n e r y & v i n e ya r d a U G U S t 2 0 1 4 W I N E G R O W I N G vitamins). Add a larger yeast inoculum to promote a vigorous and healthy fermen- tation, as increased additions of SO 2 to the fruit may initially cause some loss in yeast viability. After alcoholic fermentation is com- plete, you need to protect the wine with SO 2 as quickly as possible. Acetobacter will not grow during the alcoholic fer- mentation, but it may still be present in the wine; under conditions of low SO 2 content and exposure to air, these popu- lations may rapidly increase. Aside from minimizing exposure of wine to air, the principal defense against Acetobacter is to maintain a low pH and an adequate free SO 2 level. Acetobacter is inhibited at low pH, and the effectiveness of your free SO 2 is also increased. One issue with controlling Acetobacter with SO 2 is that they produce spoilage prod- ucts such as acetaldehyde that bind free SO 2 and minimize its effectiveness. This makes early control important because these bacteria can be difficult to deal with at high populations. Conduct a rapid malolactic fermenta- tion by following best practices for this procedure to minimize the time the wine spends without SO 2 . During élevage wines should be protected from air by filling tanks and barrels as completely as possible and ensuring barrel-topping over time. In addition, minimize air pick-up when wines with a high count of Acetobacter are being moved during racking, pumping, fining and bottling operations. Summary Consider the following tactics in dealing with damaged fruit: • Sort fruit prior to processing. • Increase SO 2 addition during fruit pro- cessing. • Minimize exposure to air during cold soak (inert gas or dry ice) or do not perform a cold soak. • Lightly press whites with excessive Botrytis damage, settle juice quickly and remove from gross juice lees. • Assess YAN and make adjustments — microbial rot will reduce YAN and vitamins, and SO 2 addition will reduce thiamine content. • Increase vigilance in the cellar post- fermentation to prevent Acetobacter growth: Maintain a low pH and opti- mum SO 2 management, protect wine from air. PWV Bibliography 1. Barata, A., M. Malfeito-Ferreira and V. Loureiro. 2012 "The microbial ecology of wine grape berries." Int. J. Food Microbiol. 153: 243–259. 2. Barata, A., S.C. Santos, M. Malfeito- Ferreira and V. Loureiro. 2012 "New insights into the ecological interaction between grape berry microorganisms and Drosophila flies during the develop- ment of sour rot." Microb. Ecol. 64: 416–430. 3. Bartowsky, E.J., and P.A. Henschke. 2008 "Acetic acid bacteria spoilage of bottled red wine—a review." Int. J. Food Microbiol. 125: 60–70. 4. Drysdale, G.S., and G.H. Fleet. 1988 "Acetic acid bacteria in winemaking: A review." Am. J. Enol. Vitic. 39: 143–154. 5. Du Toit, W.J., and I.S. Pretorius. 2002 "The occurrence, control and esoteric effect of acetic acid bacteria in winemaking." Ann. Microbiol. 52: 155–179 6. Du Toit, W.J., I.S. Pretorius and A. Lonvaud-Funel. 2005 "The effect of sulphur dioxide and oxygen on a strain of Acetobacter pasteurianus and a strain of Brettanomyces bruxellensis isolated from wine." J. Appli. Microbiol. 98: 862–871. 7. Steel, C.C., J.W. Blackman and L.M. Schmidtke. 2013 "Grapevine bunch rots: Impact on wine composition, quality, and potential for the removal of wine faults." J. Ag. Food Chem. 61: 5198–5206. JOIN US IN BORDEAUX FRANCE for the VINITECH TRADE SHOW 2014 Welcome dinner, superb lunches in Medoc and Saint Emilion. Visit fi ve of the worldʼs most famous wineries (Grand Crus), one full day at the VINITECH show. See this exceptional itinerary and register on our site www.froggytravel.com The number of seats is very limited, reserve now! November 31 to December 5 - $1,799 Email info@froggytravel.com or call 301 364 5050 for info and registration. Rate guaranteed in US$ at registration. Land only, double occupancy, all taxes included. Chateau Margaux Chateau Chambord Chateau Yquem By Premier Vacations llc Small or large groups to all France's regions AND everywhere in the world – Cruises / Europe / Africa / Asia / South America Offices in Maryland, NY and France - IATAN #21-55285-6 301 364 5050 – info@froggytravel.com - www.froggytravel.com Add 4 nights in the Loire Valley for Renaissance castles and Cabernet Franc!