to tank or barrel for fermentation, during which time the skins soak in the liquid while the sugar turns to alcohol. The grapes might be pressed at several different points depending on the style of wine (or winemaker), anywhere from mid-fermentation while sugar remains, to several months later. This variable soaking period, called maceration or skin contact, shows the importance of communication with the winery. When the pressing day finally arrives, you will need to be ready to pick up and distill the pomace immediately. Grapes for white wine are pressed immediately after harvest, yielding pomace that is sticky with sugar but no alcohol, as fermentation has not yet begun. Protecting white grape pomace from oxygen is critical, and several producers mentioned tarping off the bin and covering the pomace with a blanket of CO2 or dry ice. Excluding oxygen from the environment will help prevent spoilage, reducing the production of volatile acidity or mold. White grape pomace needs to be fermented prior to distilling. Clear Creek Distillery, which has been producing pomace brandy since the mid-1980s, adds no water or yeast, simply covering the bins and allowing natural yeast to take hold and ferment the sugar. At Stone Barn Brandyworks, we generally inoculate with a sizable yeast pitch which we then mix into the pomace with water at about 5 percent by volume water before blanketing with CO2 and sealing up the bin. Fermentation for whites can be very rapid, as short as one to three days depending on temperature, and the pomace needs to be distilled soon after fermentation. Putting the fermented pomace in a cold room can extend its life. Red pomace will generally keep a
week, and possibly longer if kept wellsealed and free from oxygen. For both white and red grapes, pressings typically get dumped into a bin, which is headed straight for the compost unless you have already made arrangements with the winery. Providing your own macro-bins to the winery to hold until they are ready to fill them can save some logistical headaches, but talk with the winemaker about pomace volume. It takes about four tons of grapes to produce one ton of pomace, which is important to keep in mind as winemakers often think in terms of juice yield, not pomace volume. It can be very disheartening to get the call for pick-up and clear the schedule for production, only to find 300 pounds of pomace when you expected 2000. Jake Soule at Admiralty Distillers in Port Townsend, Washington found it can take a few “go-rounds” to get on the same page with the winery, so it can be helpful to work with the same wineries each year. Visiting them and having them visit you before harvest time can be a great relationship builder, as well as a great way to get to know the wine portfolio to help you decide which varieties you are interested in. The other winemaking decisions that impact spirits production are whether or not the grapes have been destemmed and how hard the grapes have been pressed. Destemming is the removal of the woody green stems that hold the grapes together in bunches. This is a stylistic choice for the winery, and they might remove some, all, or none of the stems depending on the wine. When distilling, stems can add a woody, earthy flavor which some find desirable but they also impart some harshness or bitterness, as well as increasing the methanol content of the spirit. The
While I have found most [winemakers] to be happy to see their waste get used, keeping track of pomace is often low on their list of priorities, so anything you can do to simplify the process for them is greatly appreciated. 66
stems can sometimes make distillation a bit easier by preventing compaction in the pomace, with the stems providing some space and channels in the cake for vapor to escape. I have found having destemmed pomace is important for distilling white grape varietals, as the stems can add unwanted green notes which clash with the fruit and floral aromas I am seeking. Ilias Mastrogiannis, founder and distiller at Mastrogiannis Distillery in Lakewood, Washington, destems Riesling grapes and ferments the skins and juice together as a skin-contact or “orange” wine before lightly pressing to get the maximum amount of grape aromatics in his spirits. How hard the grapes are pressed has a big impact on the yield and is also the most challenging topic to reach an understanding of with a winery. As one interviewee put it, “All winemakers say they press lightly, and all of them are liars.” From the winemaker’s perspective, any juice left in the pomace is that much less wine to sell, so there are not many that generate a truly wet pomace. Again, asking questions about how they make wine and tasting through their line-up (pre-harvest) can be very helpful in finding the right pomace.
DISTILLING THE POMACE Once you have lined up pomace, some big questions remain: How will you get it into the still, how will you heat it, and how will you dispose of the pomace? Pomace is a shovel-able solid, not a pumpable liquid, so most distillery equipment and valves are not up to the task. A sizeable manway is a big help, and if the drain outlet is not at least 3 inches you’ll likely need to scoop the pomace back out the manway when done. The pomace should not be packed too tightly, as that can interfere with heat transfer and prevent vapor from escaping the grape mass. Similarly, adding a small amount of water can help the still to heat evenly
The magazine for craft distillers and their fans.