Issue link: http://winesandvines.uberflip.com/i/235959
w i inneeGMAKIN GG w R O WIN Délestage: Step 2 Délestage — Step 1 PUMP PUMP CO2 CA P CAP (Adapted from Delteil [1998]) WINE Seed Removal Délestage is a rack-and-return process modified to deport seeds, illustrated here. Fermenting juice was deported from a bottom valve through a dejuicing sleeve with holes 1/32-inch in diameter. Seeds were retained within the sleeve, and the deported juice was pumped to a separate tank while the cap was allowed to drain. Process was conducted once per day until the completion of fermentation or dejuicing, depending on the particular trial. winemaking style. For example, duration of maceration primarily influences the extraction of phenolic compounds from the seeds, 40 while fermentation temperature appears to be a primary factor influencing extraction from skins.23 Délestage Délestage, or rack and return, is a maceration technique designed to help optimize the exchange between the liquid and solid phase by emptying the fermentation vessel of liquid during aeration. Following several hours of cap-draining, the liquid is gently pumped over, or returned, to the cap. This procedure is designed to help oxygenate, while minimizing mechanical grinding of the skins, seeds and stems (Dominique Delteil, personal communication, 2003). Only if this procedure is performed to minimize mechanical extraction can délestage be considered a gentle cap management strategy. Temperature management and control when délestage is conducted may also be an important practical issue. This study evaluated délestage in conjunction with partial seed removal, to determine the impact on Merlot wine composition for three seasons and on Cabernet Sauvignon for one season. Materials and Methods Merlot fruit (approximately 8,500 kg), grown in central Virginia, was hand-harvested in each of three years at a mini46 p racti c al w i ne ry & v i ne yard JANUARY 20 14 mum of 21.0º Brix (a common soluble solids concentration for Merlot grown in central Virginia). Fruit was immediately destemmed, crushed and divided into six equal-weight (1,416 kg) replicates. Must fermentable nitrogen levels were measured, and adjusted to 250 mg/L adding either Fermaid K or Superfood™. Sulfur dioxide (30 mg/L) was added at crush to each lot. Each must was given a cold maceration (cold soak) period of 24 hours at 10º C, prior to fermentation. D-254™ yeast was hydrated, microscopically examined for budding, viability and purity, cooled to within 3º C of the must temperature, and added to each lot (24 g dry yeast/100 L). The six equal-weight lots were randomly assigned to treatments consisting of 1) control, conventional fermentation, with cap manually punched down two times per day, or 2) délestage, consisting of a rack and return procedure with seed removal conducted once per day until dryness, as follows. Following cap rise, fermenting juice was drained from a bottom valve through an external cylindrical dejuicing sleeve (2.39 mm diameter holes) into a stainless steel vat. Seeds were retained within the sleeve. The juice was pumped to a separate tank while the dejuiced cap was allowed to drain freely for two hours. Juice was then returned to the top of the cap via a tank cap irrigator, using deflection plates to minimize skin breakage. The separated Juice was brought back to top of the fermentation tank using a cap irrigation system. Délestage, therefore, involves two main features which are impacting the tannin profile of the wine (and therefore the structural/textural qualities): 1) removal of seeds could reduce the contribution of immature phenols; 2) oxidative polymerization could result in partial reduction of monomeric pigments as they are incorporated into large polymeric pigments. (For more details see www.icv.fr/ kiosqueuk/procedur/delestage.htm or www.vtwines.info/enologynotes/ onlinepublications) seeds were drained free of liquid, weighed and discarded. Treatment and control vessels averaged filled height-to-diameter ratios of 0.64 and 0.75 for the délestage and conventional fermentations, respectively. Fermentations were conducted at an average liquid temperature of 28º C (range 26º to 35º C) and an average cap temperature of 30º C (range 28º to 37º C) in 1,000-L capacity vessels. Pressing was performed at dryness (2.0 g/L reducing sugar) using a tank press to 1 bar. Freerun and press-run wines were combined. Cabernet Sauvignon fruit (18,144 kg) grown in northern Virginia was handharvested at 23º Brix, immediately destemmed, crushed, sulfur dioxide (30 mg/L) added, fermentable nitrogen levels were measured and adjusted, and divided into treatment lots (as described above). Musts were given a cold maceration (cold soak) period of 48 hours at 10º C prior to fermentation, and yeasted (as described above). Treatments consisted of 1) fermentation using 10,000-L mechanical pigeage, or 2) délestage conducted in similar size and shape static stainless steel fermentation tanks (fill height to diameter ratio, 1:1). Pigeage consisted of punching the cap three times daily, 10 minutes per punch, with punching consisting of cycles of one minute down and 30 seconds up. Délestage was conducted daily as described above with the following exception: liquid was drained onto a flat tray (0.75 x