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WINEMAKING TECHNICAL SPOTLIGHT 50 WINES&VINES August 2015 Symposium in Sacramento, Calif. "I never liked the results of the traditional destemmer, and I was always hoping that somebody would have the forethought to create something that was more gentle and effective at separating the berries from the rachis," she said. Like all machines, the destemmer and sorter took some time to get used to, but Vierra said she and her team have it well dialed in and know how to adjust it for certain varieties and vineyard blocks. She has found that it helps to grease the machine after every 10 hours of operation. For Cabernet Sauvignon and the other Bor- deaux varieties, Vierra will often place a custom- built crusher by Burgstahler Machine Works in St. Helena, Calif., beneath the Pellenc. A Francesca must pump from ColloPack Solutions pushes the must via a hose through an opening in the wall that separates the crush pad from the cellar directly into tanks. Vierra said before she purchased the crusher she tried using the pump at a high speed to crush Cab- ernet berries and instead wound up with quite a few intact berries in the tank. "So that kind of spoke volumes to the gentleness of the pump," she said. Derby only produces a small amount of white wine, and typi- cally it's a Pinot Gris. The grapes for this wine are pressed in a Di- emme bladder press. The juice is sent directly to a tank where it settles before getting racked into another tank for fermentation. Vierra has done a few experiments with small batches of Albariño and Grenache Blanc fermented in a clay amphora that she said does add an intriguing complexity to the wine. The bladder press is also used to produce juice for the Derby rosé, which is made with whole- cluster pressed Mourvedre. Vierra also has a Diemme basket press that she uses for the red wines. Both presses are from ColloPack Solutions. She worked with San Luis Obispo, Calif.-based equipment fabricator Steve Rinell ("Stainless Steve") to produce a hopper with adjustable legs on casters, which she uses to fill the basket for the press or bins for small-lot fermen- tations. She said she likes the Di- emme basket press because it has an "intelligent cycle" that can de- tect back pressure and adjust the press cycle accordingly. "If you're doing some whole cluster, and it senses a lot of the back pressure because of those whole berries, it's not going to just continue to press to a certain amount that's pro- grammed. It detects that back pressure and throttles off a little bit until it gets to the point that it's safe to push a little bit more," she said. "It's a longer press cycle with that, but we gain quality." The biggest obstacle at the winery is that the fermentation cellar is separated from the out- side crush pad with no door pro- viding direct access. To reach the crush pad from the cellar, one has to walk through a roll-up door on the east side of the building, walk around the building and enter the crush pad through a fence. An easy solution would have been to just cut a new door through the wall separating the crush pad from the cellar, but that wasn't an option in a historic renovation. Vierra admits it's not ideal, but she and cellar master Ethan Heller communicate via walkie talkies when filling a tank from a press on the crush pad or other jobs where commu- nication between the two areas is necessary. "You've got to know your blind spots in the cellar," she said. Fermentation and aging The winery is equipped with stain- less steel fermentation tanks in varying sizes and from a few sup- pliers. The largest are three 1,500-gallon tanks from Paul Mueller Co. in Springfield, Mo., that can handle 6 to 7 tons of grapes. Vierra also has three 4-ton tanks by JVNW in Canby, Ore., that feature removable lids so she can use them as open-top fermentors as well. Small-lot fermentations take place in MacroBins as well as Transtore tanks that range in size from 250 to 550 gallons. All of the tanks can be linked to a hot and cold glycol system. Because she's working with so many different varieties in the cellar, Vierra inoculates all of the must and juice with yeast to add a layer of control. She said she conducts a nutritional analysis on all juice lots and then picks a yeast strain that fits each lot's parameters to achieve "painless fermentations." For whites and rosé, Vierra uses yeast that can ferment at 48°-52° F. "On the flip side, I have also have some high-Brix lots, and I use a yeast that is capable of fin- ishing those fermentations," she said. "I've found commercial yeasts to be beneficial for those types of variables, not necessarily for flavors and aroma profiles." Red wine fermentations are Screens inside the tanks keep seeds and skins separate from the juice during pump overs. BOTTOM: KEVIN ARCHAMBEAULT This custom-built crusher is often used for Bordeaux varieties.