Progress 10/01/05 to 09/30/07
Outputs
Grape pomace is an important solid waste generated in the production of grape juice and wine. It represents nearly 20% of the weight of fresh fruits. Disposal of the large-volume waste has posed serious environmental and economic problems. There is a need to find ways to convert grape pomace to a variety of marketable products. Grappa is a traditional distilled spirit made by distillation of fermented grape pomace. Methanol in wines and distilled fruit spirits is a product formed during fermentation by the action of pectic enzymes on pectin. Methanol is a toxic compound whose consumption can cause blindness or death. The United States legal limit on methanol in grappa and other distilled fruit spirits is 700 mg per 100 mL of absolute alcohol or 280 mg per 100 mL of 40% alcohol. This research was undertaken to determine the effect of grape variety and processing conditions on the methanol content of grappa made from white grape varieties grown in the Finger Lakes wine
region of New York state. The amount of methanol in grappa varied considerably with the grape variety and the fermentation time. The mean concentrations of methanol in grappa made from the pomace samples of Cayuga White, Chardonnay, Gewurztraminer,and Riesling grapes were estimated to be 130, 112, 158 and 215mg per 100 mL of 40% alcohol, respectively, after 1 week of fermentation under similar processing conditions. Extending the fermentation time from 1 week to 4 weeks resulted in a significant increase in the methanol content of grappa. The distilled grape spirits made from the pomace samples of New York state white varieties after 8 weeks and 12 weeks of fermentation, however, still had methanol concentrations below the legal limit of 280 mg per 100 mL of 40% alcohol.
Impacts
The results of this research clearly indicate that the white grape pomace generated in New York state farm wineries could serve as a substrate for the production of distilled grape spirits. It is anticipated that successful commercialization of grappa production from grape pomace would enhance the economic viability in the rural communities of upstate New York. The grape growers and the wine industry would benefit economically from the sales of distilled grape spirits made from grape pomace.
Publications
- Hang, Y.D., Woodams, E.E. and Sun, Q. 2007. Effect of grape variety and fermentation time on the methanol content of grappa. Paper 053-02. In Book of Abstracts, 2007 IFT Annual Meeting, Chicago, IL. Institute of Food Technologists, Chicago, IL
- Hang,Y.D.and Woodams,E.E.2007. Methanol content of grappa made from New York grape pomace. Bioresource Technol(2007), doi:10.1016/j.biortech.2007.07.065
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Progress 01/01/06 to 12/31/06
Outputs
We determined the suitability of the sweet pomace of New York grape varieties as a raw material for production of grappa, one of the value-added European distilled spirits. The ranges of ethanol and methanol in the fermented pomace samples were nearly 4.0-6.0 percent and 0.010-0.036 percent, respectively. After distillation, the methanol levels of grappa made from Niagar, Cayuga White, Gewurztraminer, Chardonnay and Riesling grapes were found to be 44, 38, 138, 55 and 112 milligram per 100 mililiters of grappa containing 40 percent (80 proof) ethanol, rspectively. Our studies indicate that the white grape pomace generated by the wine industry in the Finger Lakes wine region of New York State can be used in the production of grappa with a level of methanol within the United States legal limit.
Impacts
The expected impact of this research is that the grape growers and wine industry in New York State would benefit economically from the conversion of a sold waste material into high-value products such as grappa and other distilled spirits.
Publications
- Hang, Y. D. and Woodams, Y. D. 2006. Production of grappa from sweet pomace of New York grape varieties. Paper 020B-08. In Book of Abstracts, 2006 IFT Annual Meeting, Orlando, FL
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