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GRAPEGROWING romolecules produced varied between 230 and 630 mg/L, and they contain 20%30% glucose and 70%-80% mannose.1 five months without stirring. Non-stirred wines had greater fruit intensity.24 nents, polysaccharides and proteins in their presence.20 Heavy and light lees Malolactic fermentation and lees MLF reduces the harshness of new oak and aids in development of complexity. Traditionally, stirring is continued until MLF is complete. After that, lees are more dense, which aids in clarification. This regime may be changing with the increase in co-fermentation of yeast and lactic acid bacteria. As Lactobacillus spp. have proteolytic activity, there may be an increase in the mannoprotein compo- Sensory impacts Winemakers differentiate between light or secondary lees and heavy or primary lees. Heavy or primary lees can be defined as those that precipitate within 24 hours immediately post-fermentation,4 and are composed of large particles (greater than 100 micrometers) consisting of grape particulates, agglomerates of tartrate crystals, yeasts, bacteria and protein-polysaccharide-tannin complexes. Light or secondary lees can be defined as those that precipitate from the wine more than 24 hours post-fermentation.3 These are composed mainly of small particles (1-25 micrometers) including yeasts, bacteria, tartaric acid, protein-tannin complexes and some polysaccharides. There is little value in storing red or white wines on primary lees. Such storage can result in off-aroma and flavors, and depletion of SO2. Light lees storage, however, can have a significant advantage in structural balance, complexity and stability. Bâtonnage During lees contact, wine composition changes as the yeast commence enzymatic hydrolysis of their cellular contents. An important feature is the process of proteolysis, whereby proteins are hydrolyzed to amino acids and peptides. These compounds result in an increase in the available nitrogen content of a wine.13 Amino acids can act as aroma/flavor precursors and possibly enhance wine complexity. They may also help support the growth of microorganisms in wine.13 During élevage what is sought is slow, managed and controlled oxygenation. Some lees contact may allow for oxygenation, while limiting oxidation. In Burgundy red wines have been traditionally racked off the lees in March, usually when MLF is completed. Frequently this is an aerobic racking, then back into oak on light lees, followed by an SO2 addition. Light lees are said —From Our Table To Yours— Family Winemakers of California Tasting AUGUST 17 1-6 Trade; 3-6 Public AUGUST 18 1-5 Trade Only Festival Pavilion Fort Mason Center San Francisco Lees stirring and duration Lees stirring and frequency are important, both as practical and stylistic considerations. M. Feuillat et al. demonstrated that periodic stirring of lees increases the mannoprotein level and amount of yeastderived amino acids.9 Red and white wines aged on their lees in barrel exhibit an increase in macromolecules. Stirring is a stylistic tool that generates an oxidative process that can change the sensory balance between fruit, yeast and wood by enhancing yeast components, reducing the fruit and, to a lesser degree, the perception of wood-derived aroma/flavor. Stirring may have the effect of enhancing secondary chemical reactions, possibly as the result of oxygen pick-up. W. Stuckey et al. demonstrated increases in sensory scores in Chardonnay wines stored for Meet California's fascinating family-owned wineries, hear their stories, taste their wines, share with your family and friends. To attend visit: www.familywinemakers.org pr actica l win ery & vin eya rd AU GU ST 20 13 77