Abstracts from Presentations at the ASEV Eastern Section 37th Annual Meeting & National Viticulture Research Conference, 16–19 July 2012, Traverse City, MI

s are in the approximate order as noted in the conference program. Abstracts here are those submitted and accepted through the 2012 ASEV-ES Annual Meeting Call for Abstracts. * Indicates corresponding author; † indicates presenting author. doi: 10.5344/ajev.2012.ea Quantitative Analysis of Phytic Acid in Grape Seeds, Stems, and Berries of Cabernet franc and Petit Verdot Zhiyu He† and Brent Trela.* Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409 (trelab@alertaesthetics. com) Phytic acid is a strong chelator and antioxidant naturally present in plant seeds. It has been shown to help prevent metal cation catalyzed oxidation and improve protein stability in wine, although it is not a permitted additive in wine. This research was undertaken to quantify phytic acid content in grape stems and berry parts, those parts involved in the winemaking process that might contribute phytic acid to the resulting wine, and thus provide evidence that phytic acid may be an appropriate wine additive. Phytic acid was measured in grape berries and stems of Cabernet franc and Petit Verdot. There were significant differences in concentration between the two varieties and among stem and berry parts. Cabernet franc and Petit Verdot phytic acid contents ranged from ~14.6 to 23.4 mg in 1 gram of fresh berry at veraison to 9.8 to 6.9 mg/g at harvest (23.6 to 24.1 Brix), respectively. More than 80% of the phytic acid content in the grape berries for both varieties was found in the seeds, 3 to 9% was found in the skins, and the remainder in the pulp. Phytic acid content on a fresh weight basis in Cabernet franc stems decreased from 36.1 mg/g at veraison, to 28.7 mg/g at the middle of maturation, and then increased to 50.5 mg/g at harvest. Results on a dry weight basis also showed similar changes in phytic acid content. Although not measured, these changes may be due to transportation and utilization of phytic acid as a phosphorous source. Understanding the Relationship between FermentationDerived Aromas and Juice Nitrogen Composition Mark Nisbet,† Anna Katharine Mansfield,* Tim Martinson, and Gavin Sacks. Department of Food Science, New York State Agriculture Experiment Station, Cornell University, Geneva, NY 14456 (akm87@ cornell.edu) Fusel alcohols and their acetate esters are important components of a wine’s sensory profile. Their final concentration is a function of the nitrogenous compounds found in grape must, such as ammonia (AMM) 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 concentrations required for efficient fermentation. Low nitrogen is associated with the production of sulfur off-odors, so supplementation is common. Inorganic nitrogen, added as diammonium phosphate, 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 gas chromatography–isotope ratio mass spectroscopy. The results will be modeled using partial least squared regression techniques 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 finetune the amount and types of nitrogen supplements used, reducing costs and enhancing wine quality. Effect of Cold Soak and On-Skin Fermentation on the Phenolic Content of Aromatic White Wines Diane M. Schmitt,† David C. Manns, and Anna Katharine Mansfield.* New York State Agriculture Experiment Station, Cornell University, Geneva, NY 14456 (akm87@cornell.edu) In aromatic white wines produced from Vitis vinifera and hybrid grape cultivars, phenolic compounds may contribute to color and taste. In an effort to determine the impact on phenolic concentration in aromatic white wines, replicates of Riesling, Gewüztraminer, and Valvin Muscat were cold-soaked for 2, 4, 24, and 48 hr, and fermented on the skin for 7 days. Samples were collected after rushing, pressing, and at the end of fermentation for quantitative analysis of phenolic compound composition using HPLC. HPLC analysis revealed that gallic acid, protocatechuic acid, catechin, epicatechin, grape reaction product, t-caftaric acid, c-coutaric acid, t-coutaric acid, t-fertaric acid, and quercetin-3-glucoside were the most prevalent phenolic compounds observed. In addition, coumaric acid, ferulic acid, caffeic acid, and quercetin-3-galactosidase where found in select samples of both Riesling and Gewürztraminer wines. Ethyl esters of caffeic and coumaric acid where also found in select Riesling samples, while dihydroxybenzoic acid, sinapic acid, coumaric acid, quercetin3-rhamnoside, and quercetin were found in select Gewürztraminer samples. Skin fermentation treatments showed the greatest increase in gallic acid, catechin, and epicatechin concentrations compared to the controls. Of the compounds analyzed, the flavan-3-ols and hydroxycinnamic acids, which contribute to bitterness and browning, are the most likely to affect wine sensory profiles. Composition of Enological Nutrients and Their Effect on Malolactic Fermentation Alison M. Sudano† and Ramón Mira de Orduña.* Department of Food Science and Technology, New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456 (rm369@cornell.edu) In current enology, it is customary to supply musts with nutrients to prevent sluggish and stuck fermentations. Enological nutrients may be legally added in most winemaking countries and may contain yeast and yeast-derived ingredients, ammonium salts, and vitamins. A recent market analysis reveals over 100 different commercial brands claiming varying compositions and enological advantages. However, in contrast to microbiological media used in laboratories, 580A – 2012 ASEV Eastern Section Abstracts Am. J. Enol. Vitic. 63:4 (2012) detailed compositional data about these nutrients are rarely available, which makes it difficult to evaluate their suitability to support wine microorganisms. In this study, six enological nutrients were subjected to a comprehensive analysis. Moisture, amino acid and vitamin profiles, elemental composition, and concentrations of inorganic ammonium, primary amino nitrogen, and glutathione were measured. Considerable differences were encountered among the nutrients. The elemental contents differed several-fold for some nutrients (Li, K, Ca, P, Mg, Zn, Fe, and Cu) and exceeded one order of magnitude for others (Na, S, and Mn). Significant differences were also found with regard to the vitamin and amino acid profiles and glutathione concentration. Because of their tedious nutritional requirements, wine lactic acid bacteria were chosen as test microorganisms to study the nutritional quality of the products. Two Oenococcus oeni and one Lactobacillus strain were grown in a hydroalcoholic test solution with added nutrients at two different titers (1 x 105 and 1 x 106 cfu/ mL). The extent of growth stimulation by individual nutrients was strain-dependent. The growth-supporting effect of nutrients was more pronounced at low inoculation densities. Hence, the ability of nutrients to stimulate growth seems more relevant for spontaneous MLF. At high inoculation rates, significant malic acid had already been depleted at the onset of growth. Amino Acid Profiles and Yeast Assimilable Nitrogen in Hybrid Winegrapes from the Eastern United States Amanda C. Stewart† and Christian E. Butzke.* Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907 (butzke@purdue.edu) Yeast assimilable nitrogen (YAN) is an important consideration in fermentation management. The two main sources of YAN are ammonium ions and α-amino acids. The impact of prefermentation amino acid profile and concentration on aroma and flavor development in wine is an area of current research and products have been designed to alter the amino acid profile to increase production of fruity esters by certain strains of Saccharomyces cerevisiae. This research operates largely under the assumption that proline and arginine are the most prevalent amino acids in winegrapes. Notwithstanding, we have observed substantially different amino acid profiles in winegrapes common to the Eastern United States. Comparison of profiles from hybrid varieties with Vitis labrusca parentage against profiles of Vitis labrusca varieties suggests that amino acid profile is heritable. We are also investigating this relationship for Vitis riparia hybrids and Vitis rotundifolia (Muscadine). Amino acid profile should be considered when designing yeast nutrients for hybrid and native winegrape applications. We have also surveyed YAN in winegrapes across several Midwest and Southern states, observing a range of 89 to 938 mg/L across one vintage, over 30 grape varieties, and four states. For some varieties, average YAN far exceeds our previous recommendations for YAN based on initial sugar content (200, 250, or 300 mg/L at 21, 23, or 25 Brix, respectively). Understanding the differences in amino acid profile and total YAN concentration between hybrids and Vitis vinifera is essential to developing targeted fermentation management strategies. Validation Study of Stir Bar Sorptive Extraction of Ultratrace Volatile Compounds in Wines Yanmei Zhang† and Brent Trela.* Department of Plant and Soil Science, Texas Tech Univers