12 minute read
On the Marc
What if a winery could turn its waste into electricity? What if that same waste could be used to treat diabetes, or turned into a natural food stabilizer? What if it could help with greenhouse gas emissions and provide a gluten-free alternative in baked goods?
As farfetched as these concepts may sound, researchers across a variety of fields are exploring ways to keep the over 200 million pounds of grape skins, stems and seeds produced each year in California out of the landfills and instead turn them into valueadded products.
Grape pomace, or grape marc, is the solid product that remains after the winemaking process. This mass of stems, seeds and skins was one of the first forms of agricultural waste and can be traced back to 4100 BC in Armenia, one of the oldest discoveries of wine production. Ever since the beginnings of winemaking people have pondered what to do with the remaining product.
The first written mention of its use was a proclamation by Italian Emperor Maximilian II in 1569 that granted a musician the exclusive rights to produce grape-seed oil. Grape seeds are notoriously hard and difficult to press and it takes over one ton of grapes to yield just eight ounces of oil. Despite the abysmal yield, grape-seed oil is prized by chefs for its high smoke point, essential for cooking at high heat, and by nutritionists who cite it as an excellent source of vitamin E and fatty acids.
Wine production has evolved dramatically over the past few thousand years. Before there were reliable sources of clean water, alcohol wasn’t just for getting a good buzz, it was an important part of basic sanitation. If a feudal lord were to draw up water from his castle well there is a good chance it could be contaminated with bad bacteria. For this reason wine was an important beverage and grapes would be fermented two or even three times to extract all of the flavor and alcohol. The first run, typically sweet and alcoholic, would be reserved for the nobility; the subsequent batches of dry, lower-alcohol wine would be consumed by the working-class commoners.
By 1600, Jesuits in Spain, Italy and Germany were distilling a high-proof spirit called grappa from the grape pomace leftover from winemaking. This technique has continued to the modern day, and the beverage remains popular in Italy and parts of South America. Over the years some California winemakers have even jumped at the opportunity to make grappa with their own pomace, but complex liquor regulations make it almost impossible for wineries to perform distillations on site.
Luckily, with the help of Ian Cutler of Cutler’s Artisan Spirits, Riverbench Vineyard and Winery has been turning their Viognier grape pomace into grappa (or grape pomace brandy, if you want to respect Italy’s naming rights). Currently you can find the grappa at the Riverbench Tasting Room in Santa Maria and Far Western Tavern in Orcutt. Being neighbors in the Funk Zone likely helped build a relationship for the current grappa project, but Ian doesn’t have plans to increase his grappa production. As he explains, “Traditionally, grappa stills have a larger door for loading and removing the pomace; my stills have a smaller opening, which makes grappa distillation a challenge. Also, the pomace must be fresh out of the presses and still wet to make a great distillation, so the logistics can be challenging.”
Another likely use of grape pomace throughout history would have been as fodder for animals. The first mention of this is in Charles Cornevin's book Des Residus Industriels Dans L'alimentation Du Betail, published in 1892 in Paris. Or, if you prefer the far less sexy translation of the title, The Industrial Residues in Livestock Feed. Truly riveting stuff. Back then, feeding grape pomace to livestock would have been a convenient solution for shortages in pasture and other feed rations. The pomace could be silaged until it was needed and then unearthed and used as an emergency feed ration for animals. It would be another hundred years before agricultural researchers would connect the practice of feeding grape pomace to cattle and a corresponding reduction in methane production.Over the past decade, ranchers and dairies in Australia, Europe and the United States have demonstrated that adding a percentage of grape pomace to cattle feed can reduce methane (one of the most potent greenhouse gasses) production up to 20%. They speculate that this occurs because of a chemical change in the cow’s gut biome that limits the methane that is produced by the animal and subsequently belched into the atmosphere. The impact of this methane reduction is amplified when you consider that grapes left to compost actually produce methane on their own.
Currently animal nutritionists are studying the optimal ratio of pomace to other feeds in order to keep the benefits of methane reduction without slowing the cattle’s growth or milk production. Blair Fox, head winemaker at Fess Parker and owner of Blair Fox Cellars, explains that in the past, “grape pomace would have been recycled back into the vineyard. Today all of our grape pomace is put in silage and used to feed the herd of Wagyu cattle on the Fess Parker Ranch.”
Few people have spent as much time researching and working with grape pomace as Valentin Humer, the founder of Salute Santé!, a Napa Valley company that specializes in cold-pressed grape-seed oil and grape-seed flour. Valentin has dedicated the past 25 years toperfecting the art of making grapeseed oil. Although the oil has been produced for over 500 years, only recently has cold-pressed grape-seed oil been available. Unlike traditional methods, cold pressing is a strictly mechanical process that extracts the oil from the seeds without the use of heat or added ingredients. The temperature is important when making oil because high heat will damage the oil’s fatty acid profile and ultimately contribute to oxidation and less overall flavor in the final product.
Valentin grew up in Austria, a country known for its cold-pressed pumpkin-seed oil. A chef by trade, Valentin was aware that grape-seed oil was a staple in French kitchens and he wondered whether it would be possible to produce a higher-quality oil using traditional cold-pressing techniques. Unfortunately, the traditional presses used for pumpkin-seed and other cold-pressed oils were no match for the hard casings of the grape seeds. It would take him 15 years to develop a process for sorting the seeds and producing the over 8,000 pounds of force required to remove the oil from the seed. Salute Santé! produced its first batch of oil in 1994. The oil was a huge success and garnered critical acclaim from such iconic chefs as Jean-Louis Palladin, Jean-Georges Vongerichten and Daniel Boulud. In fact, it was Chef Palladin himself who encouraged Valentin to move his production to Napa Valley and utilize California-grown grape seeds. Years after their first conversation Valentin moved the operation to Napa Valley and finished his first West Coast oil pressing in 2010.
Around the year 2000 food scientists in Croatia and Greece began to test “grape flour” as an ingredient to replace wheat flour in baking. In 2002, Eric Leber, a professor of chemistry at Heritage University in Toppenish, Washington, challenged his students to create value-added products using the pomace cast off by local vineyards. The class came up with over 50 applications for the pressed grapes, including infused oils and grape-seed varietal flours. In 2007 Eric launched his business, AprèsVin, which sells the infused oils and flours and uses the proceeds to fund science scholarships at Heritage University.
A few years later, in Napa Valley, Salute Santé! became the first California company to make grape-seed flour available to local chefs. Since then other companies have seen potential in grape flour and started their own production companies. At one point Kendall-Jackson Winery was pushing for its own grape-flour production, but currently it seems as though the only other commercial grape-flourproducers are located in Yakima Valley, Oregon, and in upstate New York. Although this flour has excellent flavor and great potential in the kitchen, it has yet to make its way into the wider consumer spotlight and remains a largely unknown ingredient.
Over the past decade grape pomace has been getting quite a bit of attention as a dietary supplement. Much of this stems from the “French Paradox,” the anecdotal observation that the French enjoy a diet rich in saturated fats but experience comparatively low levels of heart disease. This has long been attributed to the French lifestyle embracing red wine as a part of daily life. It’s therefore not much of a stretch to look toward grape pomace as a source for antioxidants and phenolic compounds. In fact, grape pomace is a good source for both of these, as well as many other minerals, fibers and amino acids, including potassium, iron, copper, zinc, tannins and glutamic acid.
When it comes to studying antioxidant levels in food one of the most common measurements is oxygen radical absorbance capacity (ORAC) value. Essentially, a sample of the test ingredient is put in a test tube with a free-radical-producing molecule and another molecule vulnerable to oxidation. After a set amount of time the researcher will measure how well the sample protected the molecules from oxidation in the presence of free radicals. (This is why grape pomace and other foods with high ORAC values are used to naturally preserve foods.) Foods that are considered high in antioxidants, such as blueberries, typically have an ORAC range of 5,000 to 10,000. The first time Valentin sent his grape-seed products to be tested the researcher called back and said there had been a problem and more samples would be required. When asked what the issues had been, the researcher explained that the grape-seed products had tested off the charts.
A second test corroborated the first results: The product came in with an ORAC value of 70,000! It’s important to note that the USDA abandoned its database for ORAC food values, sighting an oversimplification in the way this data was being used in marketing and lack of hard scientific evidence about how the values translated to actual health benefits. While there are still no studies comprehensive enough to prove grape pomace as an effective treatment, there have been limited studies that demonstrate its potential in the treatment and prevention of both diabetes and cancer. A skeptic might point out how unlikely it would be, in a medical world driven by profit and “big pharma,” for a readily available item like grape seeds to ever get the scientific attention or funding it might deserve.
Today, as the green energy revolution continues to explode, scientists are looking for untapped material to use in biofuels. At this point you probably won’t be surprised to hear that one of the more promising resources is grape pomace. The common way to convert grape pomace to biofuel is through microbial fermentation, converting glucose into ethanol or hydrogen. However, given the limited sugar left after the winemaking process, this isn’t very efficient. To put it in perspective, if the entire harvest of grape pomace was converted into ethanol it would produce just over 2.5 gigawatt hours of electricity, roughly enough to power Santa Barbara County for eight hours. Chemists are working on ways to convert cellulose from the stems and skins directly into ethanol, which if successful would make the pomace a much more compelling source for the biofuel industry.
Even the cosmetics industry is utilizing grape seeds. A local Santa Barbara business, The Grapeseed Company, was a pioneer of this practice back in 2004, “Creating the first vinotherapy line upcycled from byproducts of the California wine industry.” You can find their full range of products at The Scent Bar in the Funk Zone or at their shop and warehouse in Carpinteria.
It’s not clear what the future has in store for grape pomace. Will it become the next darling of modern science and medicine, or will it stay confined to dumpsters and compost bins? I don’t know enough about medicine, nutrition or alternative energies to make any predictions on these fields, but I am willing to speculate on grape seeds’ culinary future.
I think the adoption of grape-seed oil and flour may be slow, but is also inevitable. Whywouldn’t chefs and cooks turn to a delicious product that is produced from one of California’s greatest agricultural resources? When a product is as delicious and adaptable as grape-seed oil and comes from just up the road, it seems like an obvious front-runner in any chef’s pantry.
As micro regional cooking continues to gain in popularity I am confident more chefs and cooks will jump on the grapeseed bandwagon. Perhaps one day demand will even be great enough that our local wineries will start having their own grape pomace pressed and milled into estate oils and flours to be sold throughout the local community.
A Chef’s Guide to Cooking with Grape Pomace
Every autumn the hills above Santa Barbara hum with farm trucks hauling large totes piled high with grapes and forklifts maneuvering bins andvats around production-room floors. Over the courseof a few weeks millions of pounds of fruit go from ripeclusters of grapes dangling off their trellises to fermentingvats of foaming juice. During this time thousands ofpounds of grape pomace—the skins, seeds and stemsdiscarded during the winemaking process—are dumpedor composted. The adventurous cook with a gregariouspersonality or a friend in the industry can easily acquireenough of this pomace to satisfy their culinary creativityfor the coming year.
Just as there are dozens of varieties of wine, so are theredozens of varieties of grape pomace. Straight from thepresses you can get the white wine varietals while lateron you can acquire the fermented pomace from red wineproduction. Each variety and style has its own uniquecharacter and not enough research has been done tohelp guide you into the right decision. In reality, if youare going to try and acquire fresh grape pomace you willlargely be at the mercy of the winemaker kind enough toshare with you.
When I look for grape pomace I look for batches thathave been hand sorted, with the least amount of stemspossible. I have had great success with Cab Franc and amoptimistic about a batch of Malbec I have in the worksthis year. The trick to processing grape pomace into flouris to get it early and allow it to dry out quickly. Whenmaking large batches I lay out the content of an entirepress on a large, clean tarp and let it dry in the sun, rakingoccasionally until all of the skins are fully dry. For homeuse you can simply fill a grocery bag with fresh pomaceand then dry it out on a sheet pan using the pilot light onyour oven or the lowest setting. The drying step is criticalbecause, left unattended, the pomace has a tendency tomold. Once dried the pomace can be placed in sealedzip-top bags and stored until ready to use.
Grinding the pomace into flour is simple, but you willneed either a coffee grinder or high-powered blendersuch as a Vitamix. Sort through the grape pomace toremove any rogue stems or other unwanted material,then transfer the dried skins and seeds into the blenderand pulse until the pomace transforms into a powder. Runthis powder through a fine sieve or chinoise and transfer
any material too coarse to pass through the sieve back into the blender to grind again. (This is what I would call a “whole-grain pomace flour” and will have much different characteristics than the commercially available flour that has had the oil and skins removed.)
You can also order grape pomace flour from Salute Sante! (GrapeseedOil.com) and AprèsVin (ApresVin.com).
Having used both the commercial and home-produced grape pomace flour I don’t have a clear favorite, but would say that the commercial product has a slightly more neutral flavor profile and therefore might be more versatile in terms of substituting in recipes where a gluten-free option is desired but flavor is not. My personal preference is for the more rustic homemade flour because of its fruity quality and added richness from the oils.)
Grape pomace flour is naturally gluten free, but for me that’s not its primary appeal. I love the flavor grape flour brings to recipes: a savory, slightly tannic and mildly acidic profile with notes of wine. Taking a simple recipe for lavash and replacing 20% of the flour with red wine flour, results in a dark dough, almost maroon, that bakes off into delicate sheets with a complex flavor that leaves your mouth watering for more. It’s more than just being delicious, it’s something in the way the tannins, glutamates and acid actually stimulate your palate.
In recipes that call for almond flour or other naturally gluten-free flours, grape flour is an easy substitution— think grape-flour macaroons with dark chocolate ganache!
The use for grape pomace goes well beyond the bakery. At The Bear and Star, Chef Trent Shank is using Cab Franc grape flour as a base for a molé-style sauce that is spooned over mushroom tamales. He also occasionally uses the ground pomace to age meat, relying on its alleged antioxidant and microbial properties to discourage the growth of undesirable molds and discoloration and its glutamates to enhance the natural flavor of the meat. You can also use grape flour in your mix when you are dredging foods for pan frying.
Grape pomace flour is truly an untapped culinary ingredient and its applications are only limited by a chef’s imagination.
Words and photos by John Cox
