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WineEast veraison, two weeks pre-harvest and at harvest) were also analyzed to determine whether early YAN determination could be used to predict harvest concentrations. A linear regression was used to estimate the harvest YAN concentration from measurements taken two weeks before harvest. This approach achieved a cross-validated R2 of 0.86, indicating good predictive power. Predicting the harvest YAN concentration two weeks before harvest may allow winemakers time to send samples to external laboratories and evaluate their supplementation needs prior to harvest. This data was based on one year of sampling; two additional years will be conducted. Need a Better Cork Supplier? All Natural Cork Closures Fresh Corks Directly From Portugal 4th Generation Family Cork Producer Free Branding Free Shipping Free iS Better Ask about our Progressive Discounts Experience the Slimcork® Advantage CALL TODAY phone (203) 681-7743 Cell (860) 335-0667 email: reliablecork@gmail.com • www.reliablecorksolutions.com Low nitrogen is associated with the production of sulfur off-odors, so supplementation is common. OneStepAd_01-09-12_Layout 1 1/9/12 10:14 PM Page 1 TERROIR: Good For Grapes, Not For Glass Understanding the relationship between fermentation-derived aromas and juice nitrogen composition. Mark Nisbet et al. (ASEV-ES 2012) presented work related to relationships between wine aroma compounds and yeast nutrition. We have known for a long time that fusel alcohols and their acetate esters are important components of a wine's sensory profile, and that their final concentrations are a function of the nitrogenous compounds in grape must, such as ammonia and primary amino acids (PAN), known collectively as yeast-assimilable nitrogen (YAN). The YAN content of New York grapes varies widely, often not meeting the minimum concentrations required for efficient fermentation. Low nitrogen is associated with the production of sulfur off-odors, so supplementation is common. Inorganic nitrogen, added as DAP, is the simplest and least expensive. Complex nitrogen sources are costly and consist of hydrolyzed yeast extracts containing PAN. Fusel alcohols can arise from two different pathways: catabolism of amino acids via the Ehrlich pathway and metabolism of sugar through anabolic pathways. The relative contribution of each pathway is currently unknown. This project aims to elucidate the contribution of volatiles from catabolic and anabolic pathways under variable nitrogen concentrations using GC–isotope ratio MS. The results will be modeled using multivariate statistics (partial least squared regression) to predict the concentration of fusel alcohols and esters based on PAN concentration. The model will be validated in Riesling musts gathered from sites around New York state. This method is new to wine applications and has the potential to allow enhancement of aroma compounds through targeted nutrition. A clearer understanding of this system will allow winemakers to fine-tune the amount and types of nitrogen supplements used, reducing costs and enhancing wine quality. WE Andrew G. Reynolds is professor of biological sciences and viticulture at the Cool Climate Oenology and Viticulture Institute at Brock University in St. Catharines, Ontario. He has written the Wine East column "What's New in Research: Summaries of Current Literature on Grapes and Wine" since 1997. Every winemaker knows that the best wine starts with the cleanest equipment and bottles. Straight-A and One Step are ecologically formulated to provide the best and safest cleaning results. Taste the Wine not the Grime One Step for easy, single-step cleansing Straight-A for heavy-duty cleaning Clearly Perfect www.ecologiccleansers.com S a le s Company – Mist Sprayers – Motor Models available American Made We offer a complete line of low volume mist blowers. Low Maintenance High Performance Excellent for spraying: VINEYARDS, vegetables, orchards, nurseries, Christmas trees, mosquitoes, cattle, chicken houses, etc. For free brochure contact: Swihart Sales Co. 7240 County Road AA, Quinter, KS 67752 References available in your area 785-754-3513 or 800-864-4595 www.swihart-sales.com Win es & Vi n es A PRI L 20 13 95