Food Science and Technology at Virginia Tech

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BRUCE W. ZOECKLEIN

Professor

14 Food Science and Technology Building (0418)
Blacksburg, VA 24061

P: (540) 231-5325
F: (540) 231-9293
E-mail: bzoeckle@vt.edu

Education:
	Ph.D., Food Science and Technology, Virginia Tech, 1995 M.S., Horticulture, Virginia Tech, 1993 B.S., Microbiology, California State University, 1972
Teaching Responsibilities:
	FST 3114 (HORT 3114), Wines & Vines ( syllabus)
Research Interests:
	My research programs are designed with applied outcomes. Such outcomes support my extension goal of education of grape growers, and juice and wine processors, about methods to maximize quality and/or lower production costs. Through knowledge of relevant scientific literature and contacts with other scientists and industry personnel, I identify and prioritize problems limiting industry development. I acquire new knowledge by planning, conducting and publishing (independently or in collaboration with other scientists) research designed to resolve limiting problems. My research has focused on raisins, grapes, juices, and wines, and has resulted in a substantial number of presentations at scientist meetings nationally and abroad. While at Virginia Tech, these efforts have been supported by more than $840,000 in competitive grants and contracts from state, regional and national agencies. Research results are quickly transmitted to the industry through extension programs, newsjournals and trade publications. My research emphasis has been in five areas: 1) reduction of the incidence of grape fungal degradation; 2) management of excessive grapevine vigor; 3) isolation, characterization and quantification of grape and wine aroma/flavor precursors; 4) the effects of viticultural and enological factors on grape-derived aroma/flavor precursors; and 5) evaluation of new grape cultivars and clones for Virginia. To help facilitate these research efforts, I obtained funding and established a research winery. Research juices and wines are regularly evaluated by industry personnel, providing a rapid and direct link between my research and extension programs. Rot degradation and excessive vegetative growth have been factors limiting yield, grape quality and industry development in Virginia. Research conducted in collaboration with other Virginia Tech scientists on grapevine canopy management (selective fruit-zone leaf removal, summer pruning and the use of plant growth regulators) has resulted in four presentations at scientific meetings and five journal publications. Methods to objectively measure rot degradation, creation of desirable wine processing steps, and maximum acceptable limits of sour-rot have been established. Industry-wide adoption of this research-generated information has resulted in significantly improved fruit quality and, subsequently, improved quality of Virginia wines. Grape quality is the most important feature governing wine quality. My current investigations involve basic research on grape-derived glycoconjugates and study of the influences of wine production on these important aroma/flavor precursors. This research is designed to create an objective measure of grape quality that positively correlates to subsequent wine quality. Through the elaboration of the nature of grape-derived aroma/flavor compounds and research on methods of precursor separation and quantification, we are now able to determine potential wine quality in the vineyard. This research (in collaboration with scientists in California and Australia), supported by USDA, the California Technology Institute and regional industry associations, is being conducted in California and Virginia vineyards under my direction. Results have provided national and international recognition of my research programs, and been reported to the scientific community through six journal publications (two additional articles are under review) and five presentations at scientific meetings. Conclusions have been conveyed to the national industry through an invited presentation at the American Society for Enology and Viticulture sponsored Unified Symposium, and a featured article in the national industry-oriented trade publication The American Vineyard, which has a circulation of over 10,000. Research findings have also been published in the bulletin of the California Agriculture and Technology Institute.
Recent Publications:
	Gump, B.H., B.W. Zoecklein, K.C. Fugelsang, and B.H. Whiton. 2002. Comparison of analytical methods for production of pre-fermentation nutritional state of grape juice. Submitted. Am. J. Enol. Vitic. Mansfield, A. K. and B. W. Zoecklein. 2002. Quantification of glycosidase activity in selected strains of Brettanomyces bruxellensis and Oenococcus oeni. Submitted Am. J. Enol. Vitic. Hartman, P. J., H.M. McNair and B. W. Zoecklein. 2002. The effect of wine matrix conditions and ingredients on 3-alkyl-2-methoxypyrazine measurement by head space solid-phase microextraction. Submitted Am. J. Enol. Vitic. Whiton, R.S. and B.W. Zoecklein. 2002. Determination of ethyl carbamate in wine by solid-phase microextraction. Am. J. Enol. Vitic. Accepted for publication. Zoecklein, B.W. and H. McMahon. 2002. The influence of prefermentation maceration, sugar concentration at press, and aging on the concentrations of Cabernet Sauvignon glycoconjugates. J. of Food Comp. and Analysis. Accepted for publication. Zoecklein, B.W., K.C. Fugelsang and B.H. Gump. 2001. Juice and wine fining. Practical Winery and Vineyard. Accepted for publication. Duncan, S. and B.W. Zoecklein. 2001. Sensory evaluation of wines. Practical Winery and Vineyard. Accepted for publication. Fugelsang, K.C. and B. W. Zoecklein,. 2001.Characterization of carbohydrate utilization of Brettanomyces bruxellensis strains. California Agricultural Technology Institute. In press. Zoecklein, B.W., K.C. Fugelsang and B.H. Gump. 2001. Analisis y Produccion de Vino. Acribia, S.A. Zaragoza Espana. Gump, B.H., B.W. Zoecklein, and K.C. Fuglesang. 2001. Prediction of prefermentation nutritional status of grape juice-The formol method. In: Methods in Biotechnology: Food Microbiology Protocols. J.F.T. Spencer, W.L. Whelan, J. Brown and A. Ragout de Spencer (Eds.). p 283-296. Humana Press, Inc. Totowa, NJ. Zoecklein, B.W., B.H. Gump and K.C. Fuglesang. 2001. Nutritional status of grape juice. In: Methods in Biotechnology: Food Microbiology Protocols. J.F.T. Spencer, W.L. Whelan, J. Brown and A. Ragout de Spencer (Eds.). p 415-426. Humana Press, Inc. Totowa, NJ. Zoecklein, B.W. and V.E. Petrucci. Crystal formation in Thompson seedless raisins. 2001. In: Treatise on Raisin Production. V.E. Petrucci, C. Clary and K. Striegler (Eds.). CSUF-Press/Malcolm Publishing. In press. Zoecklein, B.W., L. Douglas and Y.W. Jasinski. 2000. Evaluation of the phenol-free glycosyl-glycose determination. Am. J. Enol. Vitic. 51:420-423. Whiton, R.S. and B.W. Zoecklein. 2000. Optimization of head space solid phase microextraction for the analysis of wine aroma compounds. Am. J. Enol. Vitic. 51:379-382. Palma, M., L. Taylor, B. W. Zoecklein and L. Douglas. 2000. Supercritical fluid extraction of grape glycosides. J. Agr. Food Chem. 48: 775-779. Wright, J., S.S. Sumner, C. Hackney, M. Pierson, and B.W. Zoecklein. 2000. A survey of Virginia apple cider producers practices. Dairy, Food, and Environmental Sanitation. 20:190-195. Wright, J., S.S. Sumner, C.R. Hackney, M.D. Pierson, and B.W. Zoecklein. 2000. Reduction of E. coli O157:H7 on apples using wash and chemical sanitizer treatments. Dairy, Food, and Environmental Sanitation. 20:120-126. Wright, J. S.S. Sumner, C.R. Hackney, M.D. Pierson, and B.W. Zoecklein. 2000. Reduction of E. coli O157:H7 in apple cider using ultraviolet energy. J. Food Prot. Zoecklein, B.W., J.M. Williams and S. E. Duncan. 2000. Effect of grape sour rot on the composition of White Riesling (Vitis vinifera L.) grapes. J. Small Fruits Review. Vol 1:63-77. McMahon, H., B.W. Zoecklein and Y. Jasinski. 1999. The effects of prefermenation maceration temperature and alcohol at pressing on the concentration of Cabernet Sauvignon grape glycosides and glycoside fractions. Am. J. Enol. Vitic. 50:385-390. McMahon, H., B.W. Zoecklein, K. C. Fugelsang and Y. Jasinski. 1999. Quantification of glycosidase activities in selected yeasts and lactic acid bacteria. J. Ind. Micro and Biotech. 23: 198-203. Zoecklein, B.W., C.H. Hackney, S.E. Duncan and J.E. Marcy. 1998. Effect of fermentation, aging and thermal storage on total glycosides, phenol-free glycosides and volatile compounds of Riesling (Vitis vinifera L.) wines. J. Ind. Micro and Biotech. 22:100-107. Zoecklein, B.W., Y. Jasinski and H. McMahon. 1998. Effect of fermentation, aging and aging sur lie on total and phenol-free riesling (Vitis vinifera L.) glycosides. J. Food Comp. and Analysis. 11:240-248. Zoecklein, B.W., T.K. Wolf, S.E. Duncan, J.E. Marcy and Y. Jasinski. 1998. Effects of fruit zone leaf removal on total glycoconjugate and conjugate fractions concentration of White Riesling and Chardonnay (Vitis vinifera L.) grapes. Am. J. Enol. Vitic. 49:259-265. Zoecklein, B.W., T.K. Wolf, J.E. Marcy and Y. Jasinski. 1998. Effects of fruit zone leaf thinning on glycoconjugates and selected aglycones of White Riesling (Vitis vinifera L.) grapes. Am. J. Enol. Vitic. 49:35-43. Zoecklein, B.W., J.E. Marcy and Y. Jasinski. 1997. Effect of fermentation, storage sur lie or post-fermentation thermal processing on White Riesling (Vitis vinifera L.) glycoconjugates. Am. J. Enol. Vitic. 48:397-402. Zoecklein, B.W, J.E. Marcy, J.M. Williams and Y. Jasinski. 1997. Effect of native yeasts and selected strains of Saccharomyces cerevisiae on glycosyl glucose, potential volatile terpenes and selected aglycones of White Riesling (Vitis vinifera L.) wines. J. Food Composition and Analysis. 10:55-65.
Selected Funding Sources:
	Virginia Winegrowers Advisory Board Agriculture Research Institute American Vineyard Foundation California Agricultural Technology Institute California Competitive Grants Research USDA/CSREES