Issue link: http://read.dmtmag.com/i/534849
w w w. v w m m e d i a . c o m J u l y - A u g 2 015 | V I N E YA R D & W I N E RY M A N A G E M E N T 6 5 is considered stable when enough KHT crystals have been removed to ensure crystals won't form in a finished wine. The reason KHT crystals form in wines is due to the holding capacity for tartrates. Each wine has a unique holding capacity, or limit, in which KHT exists in solu- ble form. Once the holding capacity of a wine is met and exceeded, KHT becomes saturated, encouraging its crystallization and precipitation. T h r o u g h o u t t h e w i n e m a k i n g process, two factors in particular affect the solubility of KHT: etha- nol and temperature. Ethanol is created during fermentation, and this is where the solubility of KHT first starts to decrease. Low tem- peratures continue to decrease the solubility of KHT, which further promote its crystallization and pre- cipitation. The continual decrease of KHT solubility leads to eventual precipitation in the final stages of winemaking, which is when the stabilization of tartrates must be attained. DETERMINING STABILITY So how do winemakers deter- mine if their wine is stable, with a minimum potential for tartrate crys- tallization? There are a handful of ways in which this characteristic can be determined, all with vary- ing degrees of ease and accuracy; among them are freeze testing and conductivity testing. But before we get to those methods, it's helpful to understand a practice called "the seeding technique." Seeding is performed before conductivity testing, and may also be performed prior to the freeze test. Finely ground KHT powder is used as the seed for two reasons. First, KHT is added in such a con- centration to promote supersatura- tion. Supersaturation ensures that a significant portion of the pow- der precipitates out of the sample. Second, the physical presence of the powder itself provides a rela- tively large surface area, serving as a site for KHT crystallization. Studies specify a recommended seed amount of 4 g/L of KHT pow- der to promote supersaturation Divergan F – PVPP West Coast: 81 M Street Fresno, CA 93721 Tel: 559.485.2692 Midwest: 1401 Ware Street Waupaca, WI 54981 Tel: 715.258.5525 The Wine Lab TM : 640-D Airpark Road Napa, CA 94558 Tel: 707.224.7903 East Coast: 1165 Globe Avenue Mountainside, NJ 07092 Tel: 908.301.1811 The Revolutionaries Behind Wine's Visionaries Malolactic Bacteria, Non-Saccharomyces Yeasts Fermentation Nutrients Membrane Cartridge Filters, Laboratory Consumables OenoFoss - FTIR Analytical Instrumentation Filter Sheets, Lenticular Cartridges, Cellulose Pre-Coat Fibers Cross Flow Filters, RO Systems Liquid and Granular Enological Enzymes Oak-Mor ® / Oak Avantage ® Chips and Granular Oak www.gusmerwine.com sales@gusmerenterprises.com CO 2 Analytical Instrumentation Wine Hose & Spray Nozzles At Gusmer, we know the wine you create is just as unique as you are. Portable Ozone Systems H 2 S Preventing Saccharomyces Yeasts Lysozyme For over 90 years, Gusmer has oered a full range of innovative enological tools that enable your creative expression through unique and interesting wines. Equipment, analytical instruments and processing aids brought to you from leading suppliers in the wine industry, all backed by strong Gusmer technical support. The options for expression have never been greater and the tools have never been better – so go ahead, be unique, express yourself. For more information, contact Gusmer today.