ASEV 58th Annual Meeting held in Reno

Wines & Vines, August, 2007 by Tina Caputo, Jim Gordon

The American Society for Enology and Viticulture's (ASEV) 58th Annual Meeting, held in Reno, Nev., June 19-22, kicked off with a Merit Award presentation to G. Stanley Howell of Michigan State University, who spoke about his work in developing a research program near the climatic limits of commercial vine culture.

While the attendance on the trade show floor appeared sparse--perhaps underlining the group's recent decision to eliminate the trade show after 2008--enthusiasm and attendance at several technical seminars appeared positive.

Electronic Noses

In a session entitled Grape & Wine Composition and Sensory Analysis, two speakers presented the results of their research on "electronic nose" evaluation of grapes and wine. Ahmad Athamneh, of Virginia Polytechnic Institute, and his team used an electronic device to compare results with those obtained through traditional testing methods, including Brix and pH measurement. After testing it in 2005 and 2006 as a tool to quickly evaluate Cabernet Sauvignon grapes for maturity, Athamneh found that "The results demonstrate the superiority of the e-nose over conventional methods."

A second e-nose presentation was given by Amalia Berna, of CSIRO Food Futures Flagship, in Australia. Berna tested Cabernet Sauvignon and Riesling grapes from five different regions in Australia with varied climates. She found that the e-nose gave "excellent predictions" for hot climate regions, but misclassified some mild-climate samples. The results for Riesling, however, showed that conventional testing was more effective than the e-nose, due to low concentrations of many compounds.

Too Many Lady Beetles

Low concentrations create a different problem when lady beetle infestations occur in Midwest vineyards, according to another ASEV session. When the beetles invade grape bunches, they often get crushed along with the fruit, and add an off-putting odor, even with just a few small beetles per vine in a Minnesota Frontenac vineyard. That was a finding presented by Tederson Luiz Galvan of the University of Minnesota, Saint Paul. Even one beetle per kilogram was detected by 5% of the tasters in Galvan's study, and at five beetles per kilogram, the detection rate was 50%.

Dekkera Bounces Back

Winemakers who learned long ago that applications of S[O.sub.2] knock down Dekkera/Brettanomyces problems in wine may have to rethink their cellar practices, judging by the research summary presented by Nicole Umiker of Washington State University, Pullman.

Dekkera induced and monitored in numerous samples of fermenting wine at 3.8 pH were indeed knocked down significantly upon additions of "truckloads" of S[O.sub.2] at .3 molecular to .8 molecular, to a point where they couldn't be measured with plating. But five days later, they were back to nearly the pre-addition levels. Further investigation showed that the Dekkera went into a kind of dormant state Umiker called viable but nonculturable.

Fruit Maturity in Cabernet

Enologists listening to Kirsten Skogerson of UC Davis were probably relieved that she found a firm correlation between grape sensory analysis on Cabernet Sauvignon and sensory analysis on the wine made from those grapes. A panel of experienced tasters tended to find the same red fruit vs. black fruit, thin vs. viscous, and green flavors vs. dried fruit flavors in both steps of the process, examining multiple samples of grapes and wines harvested at Brix varying from 22[degrees] to 30[degrees] on six harvest dates.

The research included watering some of the high-sugar samples before fermentation, and de-alcoholizing other samples after fermentation. Adding water at the crusher did result in lower ripeness attributes, she said.

How to Define Body

Ron Runnebaum, also of UC Davis, presented findings of his exploratory study on the Key Constituents Affecting Wine Body. "We wanted to link chemical and physical properties to sensory attributes," he said. Traditionally, greater body was believed to come from ethanol, glycerol and total extract. For the sensory part of the study, body was defined as viscous mouthfeel.

By scientifically measuring the test wines' properties, then comparing to results of sensory analysis by trained tasters, the results "all seemed logical," he said, including findings that Chardonnay is perceived as high in body, Sauvignon Blanc low and several other varieties in between.

Promoting Vine Health

A seminar on Vine Health stressed the importance of inspection and prevention in dealing with vine diseases and pests. Speakers included Michael Monette, Sunridge Nurseries; Tia Russell, Duarte Nursery; and Judit Monis, STA Laboratories, Inc. Duarte's Tia Russell emphasized the importance of teamwork in producing and maintaining healthy vines. In addition to the preventative measures taken by nurseries, such as hot water dips and pest quarantines, Russell said wineries should do periodic testing of vineyards for viruses, diseases and pests, even if they start out with clean plant materials.

"Certified vines" have been in big demand, she said, though these vines are not always 100% virus-free. "Seek international education on virus spread," Russell advised.