Issue link: http://winesandvines.uberflip.com/i/347498
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 61 W I N E G R O W I N G tion of acetic acid, although Gluconobacter may also produce high quantities of glu- conic acid. Although we usually encoun- ter acetic acid production during wine storage and aging, you may actually detect an acetic note on damaged berries. This is due to yeast growth on damaged berries converting grape sugars to etha- nol, which the bacteria then convert to acetic acid. The major yeast found on grape berries will be Kloeckera apiculata. This yeast is capable of producing large amounts of ethyl acetate (nail polish remover smell), acetic acid and acetaldehyde. To make matters worse, the acetic acid and ethyl acetate produced by these spoilage microorganisms attract fruit flies to the damaged fruit, resulting in greater spread of the bacteria and yeast to sur- rounding fruit. Although it may be difficult or impos- sible to control events that produce dam- aged or compromised fruit, there are a number of steps that you can take to min- imize the impact this damage will have on wine quality. The first and perhaps most important step is rigorous sorting, both in the vine- yard and at the winery. While the degree to which you sort and discard fruit may ultimately be ruled by economic deci- sions, removal of visibly damaged fruit will significantly reduce the risk of sub- sequent wine spoilage issues. For both red and white grapes, higher levels of SO 2 should also be added at the crusher or press. This will help reduce the number of spoilage yeast and bacteria and aid in preventing oxi- dation of color compounds by the enzyme laccase. Laccases are a class of e n z y m e t h a t c a n b e p ro d u c e d b y Botrytis, and while SO 2 does not inhibit lacasse activity directly, it can scavenge O 2 , which is needed to cause oxidative spoilage. For red wine, minimize the time between crushing and fermentation. This may mean reducing or eliminating a cold soak. If cold soaking does occur, then limit exposure of the grapes to air by blanketing with inert gas and/or applying a dry ice addition to the sur- face of the fermentor. Once fermenta- tion begins, the CO 2 produced will set up an anaerobic environment that will inhibit the growth of Acetobacter and Kloeckera. For white wine, whole-cluster press lightly to minimize the impact of Botrytis. In addition, clarify quickly (cold temper- ature) and consider adding settling enzymes. This will allow rapid removal of the juice from the heavy lees and reduce the risk of enzymatic oxidation. If you have heavily Botrytis-infected grapes, consider fining the juice with bentonite, casein, PVPP or combinations. Many commercial products are available that are combinations of these fining agents. Determine product and rate using bench-top trials before making additions to a larger volume. When it comes to dealing with compro- mised fruit during fermentation, the two main things to consider are nutrient addi- tions and creating a large and healthy yeast population to perform a robust fer- mentation. Microbial growth on the grapes prior to harvest and during the cold soak and early fermentation can lead to depletion of yeast assimilable nitrogen (YAN) and vitamins. In addition, a large addition of SO 2 can lead to thiamine deficiency, as SO 2 reacts with this vitamin and splits it irreversibly into two inactive ingredients. Therefore, monitor YAN and make appropriate additions of organic and inorganic nitro- gen (not just DAP as this will not replace One BirdGardSuper PRO Wireless can control birds in up to 48 acres The Bird Gard SuperPRO Controller/transmitter can broad- cast distress calls to receivers up to 1000 ft in all directions. One Con- troller/transmitter can control up to eight 4-Speaker Wireless Receivers. No need to buy 8 complete Bird Gard SuperPROs. Each 4-Speaker Wireless Receiver protects up to 6 acres. Buy 2, 3, 4, up to eight 4-Speaker Wireless Receivers to protect up to 48 acres. You not only get wireless speakers, but also the distress calls randomly jump from speaker to speaker keeping the birds from getting used to the sounds. A limited special price for one BirdGard SuperPRO Controller/transmitter & one 4 Speaker Wireless Receiver is $799 (List $1050). Each additional 4-Speaker Wireless Receiver which covers up to 6 acres is $399 (list:$520). More and more vineyard managers are replacing netting with the Bird Gard PRO series. BirdGard Wireless JWB Marketing LLC 800.555.9634 For more discounts on the Bird Gard go to : birddamage.com Bird Gard Super PRO with 4 speakers covers up to 6 aces. $599 List: $750