2014-2015 OWB Funded Research Reports
For 2014-2015, the OWB allocated up to $270,000 for the support of these research grants. Investigators are just beginning their research for the 2014-15 year. Full reports on their findings should be available early summer 2015. Below are summaries on what each investigator will be researching and what he/she hopes to find.
Walter Mahaffee, Research Plant Pathologist at the Horticulture Crops Research Laboratory, USDA-Agricultural Research Service, Grower Implemented Quantitative LAMP for Initiating and Adjusting Fungicide Program
A quantitative molecular (qLAMP) procedure that is highly specific and robust for detecting grape powdery mildew inoculum across 17 commercial vineyards was developed. qLAMP takes approximately 10 min for DNA extraction and reaction setup and another 30 min to run using equipment that costs less than $2000 to obtain from commercial vendors. These results continue to indicate that use of inoculum detection for initiation of fungicide applications for grape powdery at the grower level will be commercially feasible in the near future. In 2014, viticulturist at commercial vineyards will test the performance of qLAMP for detecting powdery mildew inoculum and adjusting fungicide application intervals and further reduce the economic and environmental costs powdery mildew management.
Michael Qian, Department of Food Science and Technology, Oregon State University, Formation of Volatile Sulfur Compounds in Pinot Noir During Barrel Aging – Part Two: Lees Level and Contact Time on Volatile Sulfur Compounds in Wine
It has been observed among Oregon wineries that sulfur off-flavor can develop during lees wine aging, and that the off-flavor problems are often more serious in cooler years. The objective of this research is to study the effect of amount of wine lees and lees contact time on the release of volatile sulfur off-flavor during barrel aging. Pinot noir wines were be produced with two different commercial yeast strains, one with low/no H2S producing yeast strain Saccharomyces cerevisiae P1Y2 while a second one with Saccharomyces cerevisiae RC212. Three different lees levels (heavy, medium and light) were studied over 9 month period. Eight volatile sulfur compounds were detected and the concentrations of volatile sulfur compounds in the wines fermented with both two yeasts were relative low. Saccharomyces cerevisiae P1Y2 produced lower levels of H2S, methyl thioacetate and methionol than Saccharomyces cerevisiae RC212. During lees-aging process, methyl thioacetate was constant, whereas hydrogen sulfide, dimethyl sulfide, dimethyl disulfide and dimethyl disulfide increased at first several months then started to decrease. There were no obvious differences among the different lee levels through aging despite of yeasts used in fermentation. The results demonstrated that the lees level and contact time is not the sole cause for sulfur off-flavor development during barrel aging. Lee composition may play a more important role. Off-flavor wines from collaborating wineries were also studied. It was shown that all off-flavor wines were due to high level of H2S, and addition of copper mitigated the problem.
Michael Qian, Professor of Flavor Chemistry, Department of Food Science and Technology, Oregon State University, Understanding Pinot Noir Grape and Wine Aroma Composition as a Result of Changes in Vine Balance
Crop thinning is commonly implemented in most vineyards of Oregon to regulate crop level, but its practicality has been questioned because of increased production costs and lost yields, as well as lack of knowledge of the relationship between crop thinning and Pinot Noir grape and wine quality. Effects of severity and timing of crop thinning practice on Pinot Noir grape and wine volatile compositions were investigated over three growing seasons (2010, 2011, and 2012) in a commercial vineyard of western Oregon. Crop levels were moderately (35% crop removed) or severely (65% crop removed) thinned at pre-bloom, fruit set, lag phase, or véraison and compared to full crop treatments (control). Grape and wine volatile compositions were analyzed by GC-FID and GC-MS. Results showed that crop thinning practice affect some of the yeast-generated volatile composition. Crop thinning increased levels of certain higher alcohols (e.g., trans-3-hexenol, 1-heptanol, and propanol), but decreased levels of some esters (e.g., ethyl hexanoate, ethyl isobutanoate, ethyl 2-methyl butanoate, and isoamyl acetate). However, crop thinning practice had very limited impact on the grape-derived terpenoids and C13-norisoprenoids.
Patty Skinkis, Assistant Professor and Viticulture Extension Specialist, Department of Horticulture, Oregon State University, Defining Crop Load Metrics for Quality Pinot Noir Produced in Oregon
Do low yields equal better wine? Premium winegrape producers worldwide boast of low yields that concentrate flavors. This same concept has driven yield management practices in Oregon, where low yield targets are thought to produce the best wine quality.However, these targets are not scientifically founded and are applied universally, without considering differences in vineyard designs and vine health. The goal of this research is to define target yields in the context of vine canopy size and function. The project has been implemented in 16 Pinot Noir vineyards in the Willamette Valley to test how vine yields influence growth, fruit composition and wine quality. This project will provide vineyard and winery producers with better metrics to evaluate quality than using a one-size-fits-all target yield. If growers are able to increase their vineyard yields without compromising fruit and wine quality, they will reduce canopy management costs and increase profits, thereby making a more sustainable business.
Elizabeth Tomasino, Oregon Wine Research Institute, Department of Food Science and Technology, Oregon State University, Chiral Terpenes – Quantitation, Threshold Determination and Sensory Impact on Aromatic White Wines
This project investigates a specific class of compounds, chiral terpenes (floral, citrus and fruity aroma compounds), and links chemical composition to sensory perception and ultimately impact to wine quality and consumer preference. The importance of monoterprenes to aromatic white wines has been well established but the fact that many of the compounds are chiral has been overlooked. Chiral compounds are chemical compounds found throughout nature and are compounds that are structurally identical except that they are non-superimposable mirror images of each other, known as enantiomers. Enantiomers are likely to have different perception thresholds and aroma descriptions. For instance, R-(+) limonene has a described aroma of fresh, citrus and orange like and S-(-)-limonene a described aroma of harsh, turpentine-like, lemon note. The first steps of the project are two fold;
- Survey of chiral terpenes in Riesling and Pinot gris wines based on region of origin
- Survey of chiral terpenes by white wine varietal
Once chemical composition has been achieved a range of sensory tests will be run to determine those compounds and concentration splaying a role in sensory perception and consumer preference.
James Osborne, Extension Enologist, Department of Food Science and Technology, Oregon State University, Formation of Volatile Sulfur Compounds in Pinot Noir Post-Fermentation – Part One: Role of Grape Amino Acid Content and Wine Lees Composition
The formation of volatile sulfur compounds in wine such as hydrogen sulfide (H2S) (rotten egg smell), mercaptans (rubber, garlic smells), and disulfides (cabbage, onion smells) can significantly impact wine quality and can be a challenge for winemakers to deal with. This project focused on the formation of these volatile sulfur compounds post-fermentation and the role that grape amino acids and wine lees composition play during aging. Experiments in year one of the study demonstrated that the amount of wine lees do not by themselves cause formation of volatile sulfur compounds but more likely create conditions conducive to formation of volatile sulfur compounds. Development of volatile sulfur aroma taints in wines undergoing barrel aging was due to formation of H2S and not to the formation of more complex volatile sulfur compounds. The reason for this H2S formation is currently being investigated including the role of residual elemental sulfur from the grapes and the presence of entrapped H2S from fermentation that is subsequently released once wine goes to barrel.
Laurent Deluc, Assistant Professor in grape research at the Department of Horticulture, Oregon State University, Determine the Impact of Cluster Thinning and Cluster Zone Leaf Removal on the Hormone Content of Pinot Noir Grape Berry
Dr. Deluc’s group is leading a research project intended to characterize the role of plant growth regulators on berry development and composition in cool climate region. Plant growth regulators contribute to the integration of most signals sent to the berries by either the plants themselves (nutrient and water status) or by the environment such as light or temperature. The research project studies the accumulation of these regulators from bloom to harvest and how their accumulation in berries can be affected by vineyard practices such as leaf removal and cluster thinning. This research would provide the industry with new knowledge on the accumulation of these regulators that contribute to fruit quality.
Vaughn Walton, Associate Professor, Horticultural Entomologist, Department of Horticulture, Oregon State University, Insect Vector Distribution and Disease Progression Studies to Better Describe Field Epidemiology of Grapevine Red Blotch-Associated and Vine Leafroll Virus in Oregon
Dr. Walton’s lab is working to understand and categorize the spread of Grapevine Red Blotch-Associated and Vine Leafroll Virus in Oregon vineyards. His team intends to track insect vector distribution and disease progression in established vineyard plots with the goal of collecting preliminary data on field epidemiology of grape red blotch-associated virus and grape leafroll-associated virus. He will also provide Extension information to the Oregon wine industry on the importance of vectors, leafroll and red blotch disease in Oregon vineyards. The addressed needs and outcomes for this work is based on similar approaches conducted to evaluate other vector transmission studies. This work complements other proposals from UC scientists to study grapevine red blotch disease. However, this project is unique as it focuses on the regional vineyard vectors and disease epidemiology. Information on grapevine red blotch disease epidemiology is critical to inform management decisions; grape growers must determine whether infected vines threaten adjacent healthy vineyards and take timely and appropriate action.
Patty Skinkis, Assistant Professor and Viticulture Extension Specialist, Department of Horticulture, Oregon State University, Impacts of Vine Vigor, Nitrogen, and Carbohydrate Status on Fruitfulness of Pinot Noir
Fruitfulness is the vine’s ability to produce grape clusters. The more grape clusters that are formed by vine buds, the more fruitful the vine. Growers depend on good fruitfulness to ensure sufficient yields for wine production each year. In some growing seasons, Pinot noir vineyards have been found to have lower than optimum fruitfulness and fruit set, leading to lower than acceptable yields. In other years, fruitfulness and fruit set are high, leading to significant labor costs to achieve target yields. This yearly variability can create problems with projecting vineyard management costs and potential profits. Preliminary research suggests that fruitfulness is related to vine growth and nutritional status. This project aims to better understand how vine nutrition and vine vigor enhance or decreased fruitfulness, and determine if more consistent fruitfulness can be achieved. Methods by which to maintain fruitfulness will allow growers to achieve greater crop consistency, quality, and potentially greater profits.