Location: Horticultural Crops Research2012 Annual Report
1a. Objectives (from AD-416):
Objective 1: Determine effects of water management on wine grape productivity and fruit maturity. Objective 2: Integrate the development and use of analytical methods for the evaluation of phenolic compounds and other chemical indicators of quality in fruit, fruit products, and wine. Objective 3: Determine effects of vineyard and vine microclimate on fruit development, vine productivity, and fruit quality, particularly phenolic compounds.
1b. Approach (from AD-416):
Our fundamental approach for conducting the proposed research is based on interdisciplinary work toward grape production systems and connecting production practices to the quality of the harvested fruit or value-added fruit products. Although each team member is responsible for a distinct experimental focus, overall goals and responsibilities of the contributors overlap because the interactions among system processes and properties transcend disciplines.
3. Progress Report:
ARS researchers in Corvallis, Oregon, and Parma, Idaho, clarified the confusion surrounding Rubus fruit phenolic research (e.g., misidentification of black raspberry ACYs (anthocyanins) followed by animal metabolomics study monitoring these misrepresented compounds) by identifying errors in Rubus fruit phenolic research, and how these confounding and incorrect results were derived. We completed the documentation of a computer model to predict the cold-hardiness of grapevines during winter in Washington state. Adaptation of the model by our collaborators now allows grape growers internet- and smart-phone access to estimates of the low temperatures at which there could be damage in their vineyards. We collaborated with scientists at Oregon State University and other ARS programs to investigate the influence of a clay-based foliar reflectant on heat stress in wine grape. In 2011 we published results from two years of trial data showing that the particle film did not alter grape aroma volatiles. Grape aroma is of interest to the wine grape industry because of its strong influence on wine quality. In 2011, we completed in collaboration with scientists at Boise State University, Washington State University, Brock University, Ohio State University, Agri-Food Canada and other ARS researchers, year replications of multiyear field trials designed to evaluate differences among wine grape cultivars in response to drought and tolerance to cold. Results from these multiyear trials will provide new information useful to wine grape growers who want to customize cultural practices for different winegrape cultivars.
1. Clarification of Rubus fruit phenolics. Phenolics (phytochemicals) are important quality indicators in Rubus fruit and are a diverse group of compounds that are a challenge to analyze, especially the larger molecules like ellagitannins. ARS scientist in Parma, Idaho, and Corvallis, Oregon, examined peer reviewed research papers on Rubus fruit phenolics and identified that additional studies are needed, particularly for the larger molecules. Techniques developed by ARS researchers have improved phenolic analyses in black raspberry and played a vital role in the discovery that newly collected black raspberry mutants lack certain color compounds (natural pigments; anthocyanins). These were the first black raspberry variants reported in the literature with this exceptional pigment profile; their mutation represents a possible key to deciphering the genetic control of pigment biosynthesis. Our efforts will improve healthfulness and marketability of products consumed by the general public, from the field to the fork.
2. Determination of day and night temperature swings on fruit chemistry in red wine grapes. The specific role of field temperature in determining compounds in grapes that affect wine color and astringency was anecdotally understood. What had not been scientifically demonstrated were the effects of day-to-night temperature swings in conjunction with stage of fruit development on these compounds. An ARS scientist at Prosser, Washington, in conjunction with collaborators from Oregon State University and University of California determined that the amount of these compounds was not changed by day-night temperature range, but that the types of compounds did change, which can have effects on wine quality. These findings are important to wineries that source fruit from different growing areas to create consistent products that are marketed in a price range that is economically sustainable for both the winery and the grape growers.
3. Completion of computer model of winter-hardiness in vineyards. An ARS scientist in Prosser, Washington, with collaborators at Washington State University used a large database of grapevine cold susceptibility to build a model for growers for them to anticipate the likelihood of cold damage in a specific vineyard or for a specific grape variety, when extreme cold fronts occur in late fall and winter. This model was subsequently posted by university collaborators in a form for growers to access by internet or smartphone. These findings are important because applying frost-protection measures in the vineyard is costly; information provided by the model provides growers with a decision aid tool for more cost-effective vineyard management during winter.
4. Soil moisture conditions alter grape and wine aroma volatile composition and wine sensory properties. Vine water availability is known to alter wine sensory properties, but the chemical composition of drought-induced changes in aroma volatile composition in grapes and resulting wines have not been identified. We identified volatile aroma compounds that increased in grapes and their resulting wines when vines were grown under a drought stress and found that differences in the sensory properties of wines produced from drought-stressed grapes were detected by untrained panelists. The wine grape industry contributes strongly to rural economies through farm-gate receipts, agribusiness and tourism and premium quality is essential to remain competitive in a global market. Findings from this study contribute information useful to the wine grape industry for developing water management practices that conserve water and achieve wine quality goals.Song, J., Shellie, K., Wang, H., Qian, M.C. 2012. Influence of kaolin particle film and deficit irrigation on varietal aroma components in Merlot grape (Vitis vinifera L.). Food Chemistry. 134(2):841-850.