Issue link: http://winesandvines.uberflip.com/i/70680
WineEast Since the most important function of a pre-fermentation SO2 addition is to inhibit undesirable microorganisms, grapes in less-than-stellar condition or with a higher pH should receive SO2 at the higher end of this range. Warm grapes are suscep- tible to faster microorganism growth and also should receive a higher dose. Cold, clean fruit, fresh from the vineyard, can get by with a dose closer to the lower end of this range. When add- ing SO2 to crushed grapes, thorough mixing is required. Good results can be achieved by adding the SO2 upstream of the destemmer-crusher and letting the crusher and must pump do the mixing for you. Post-fermentation additions As mentioned earlier, yeasts produce a sulfur-binding compound called acetaldehyde. As this compound is produced through the course of alcoholic fermentation, it is bound up by the available SO2 . If you measured the SO2 would find little to no free SO2 and a total SO2 Winemaking All other wines—whites especially—should receive sulfur at their first racking. The following philosophy makes this addition fairly routine for most wines: 1. I want enough SO2 present to protect the wine. 2. With alcoholic fermentation complete, the wine can be kept cold to retard microbial activity. 3. In most cases the wine won't be consumed for several months at the earliest, and a slightly elevated SO2 at this stage is not an issue. 4. Better protection is afforded by one larger dose of SO2 more frequent smaller doses. than by immediately after fermentation, you less than half of your pre-fermentation addition. The resulting loss would be due to binding, precipitation and vaporization. What this means is that for all practical purposes, the winemaker is starting from square one again. Unless there is a compelling reason, wine destined for malolactic fermentation (ML) should probably not receive any SO2 at this point. Lactic acid bacteria are highly susceptible to SO2 initiation of ML should take place as soon as possible. . Instead, Stoltzfus_Dec10.qxp 11/10/10 4:23 PM Page 1 The above philosophy, combined with experience, has led me to a standard addition at first racking of 80 ppm. The dosage of SO2 is calculated and added to the receiving tank as it is filling. I under- stand a one-size-fits-all answer is simplistic, but an addition at this level usually provides adequate protection through spring without going too high. SPREAD: Lime Fertilizer Compost Gypsum Organics Shields separate vines and limbs Spreads a wide variety of materials Can be customized to 54 inches wide Variable rate GPS available Optional banding attachments All-pto or ground drive models 2 ton or 4 ton models Call us: 800-843-8731 www.limespreaders.com 64 Wines & Vines MAY 201 1 Extenuating factors might include plastic tanks, warm cellars, a pH above 3.5, or late-harvest wines, all of which might call for 10- 20 ppm more SO2 . Sulfite bleaching can be an issue in lighter reds and rosés, and care should be taken not to overdo SO2 . Lab trials can be used to predict the amount of color loss you can expect.