Students Joseph Belsky and Katie Wayman use shovels to guide chardonnay grapes from the hopper to the elevator of the crusher-stemmer. Sue Cockrell/Enterprise photo

UC Davis

Fruits of their labor: Grape crush a learning experience

By From page A1 | August 24, 2014

“Be wary of forklift traffic,” Chik Brenneman announced to the throng of reporters and photographers at UC Davis on Thursday morning.

The crowd assembled at UCD’s Robert Mondavi Institute for Wine and Food Science came to see viticulture and enology students crush chardonnay grapes. Brenneman, winemaker and winery manager at UCD, explained that the grapes are ready a couple of weeks sooner than usual because of weather conditions.

When asked if it was a “big deal” that these grapes were ripe ahead of schedule, Brenneman answered, seemingly not wanting to cause alarm, that it “shortens the harvest … it brings things in earlier.” But, he noted, “it can be shorter,” as in, it’s OK if the season is shorter and not necessarily a sign of doom.

In fact, Brenneman explained that the weather actually can prolong other producers’ harvests. He said the team on hand was “juicing chardonnay because it is ready.”

As other questions were posed about whether Yolo County and the Napa Valley are in danger of having vineyards move north to Oregon where there was more water and less heat, Brenneman simply responded, “time will tell.”

Because the sugar levels were high, Brenneman said his team knew it was time to process these chardonnay grapes. They had reached 25 brix, a measure of density, which indicated their readiness. Students regularly pick the fruit in the field, testing sugars, among other things. The longer the grapes can stay on the vines, the better.

As far as red wine grapes, Brenneman is hoping “to stretch them to Sept. 15.” For now, the sugars in the red varieties are in the high teens and low 20s, he explained.

Grape crush
After a lull in the questions, Brenneman shifted gears to the business at hand: crushing grapes. He explained that the process would take about 45 minutes to convert the just-picked chardonnay grapes into juice for cold storage. Although he is working with summer-session students now, the bulk of the V&E students won’t be back until late September. For that reason, the juice is being readied now for cold storage.

As V&E staff research associate Paul Green maneuvered a forklift toward a large bin of green, tightly clumped fruit, fourth-year student Katie Wayman grabbed a short-handled, plastic shovel. Across from Wayman was another shovel-armed student, Joseph Belsky, who is preparing for graduate school.

Green carefully lifted the bin of grapes over the crusher-stemmer, and let gravity do the work. As the grapes landed on the hopper, they were rinsed, shaken and then loaded onto an elevator, aided by the shoveling prowess of Belsky and Wayman.

From the elevator, the grape bunches had their stems removed; the grapes traveled through the crusher, while the stems got dumped unceremoniously into a bin off the side of the machine.

Asked if these stems would be sent to UCD’s biodigester, Brenneman explained that when the master plan for the biodigester was being drafted, the very occasional waste from wine production wasn’t included. For now, the teaching and research winery composts its own waste. But stems and other byproducts of the crushing process will be part of the biodigester’s future.

Experience is the best teacher
Brenneman’s goal, above all, appeared to be getting the V&E students proficient at all aspects of the grapes-to-juice process. He seemed almost happy to have things go a tad amiss — a hose wasn’t clamped on straight to the wine press, so he directed the students to stop, then reverse the crusher-stemmer to stop the flow while he detached/reattached the hose — as a learning opportunity.

Once everything was running properly again, the juice flowed from the crusher-stemmer to the wine press, another impressive-looking piece of equipment. The deep tray beneath the press steamed with billowing smoke, resembling a haunted punch somebody would serve in a cauldron at a Halloween party.

Belsky explained that the dry ice was added to stop the juice from oxidizing.

“As soon as the juice touches air,” he explained, oxidation starts. Standard operating procedure for making wine would be to add sulphur dioxide to stop the oxidation, but because students need to work with the juice in its purest form, they have to work extra quickly, using only dry ice to slow the oxidizing.

Everybody do your share
After three bins of grapes had been dumped into the crusher-stemmer, the action slowed; Brenneman started directing his team of students to turn off the machines and start the cleaning efforts. Washing the crusher basin, disconnecting hoses, shoveling up spilled grapes are all part of the gig at the teaching and research winery.

The big question remaining is what kind of quality to expect out of this year’s yield. As UCD’s Pat Bailey said in a news release, “The jury is still out.” Time will tell.

— Reach Tanya Perez at 530-747-8056 or [email protected] Follow her on Twitter at @enterprisetanya

Tanya Perez

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