Researchers from Sonomaceuticals, LLC, the USDA-ARS, and UC Davis have collaborated to learn more about the ways in which a by-product of Chardonnay winemaking that has been viewed simply as a waste product may have potential health benefits.
Dr Torey Arvik, Dr Wallace Yokoyama, Dr Carl Keen, Dr Roberta Holt, and Fanny Lee are interested in how Chardonnay marc – the solid remains of the grapes after being pressed for their juice – could be upcycled into ingredients used in foods and dietary supplements that may improve cardiovascular and gut health. Harnessing the health benefits of Chardonnay grape marc as a value-added ingredient enables more sustainable wine production.
A grand challenge in the global food and agriculture sector is minimizing food waste and negative environmental impacts while meeting increasing global demand for healthy food. Innovation is urgently needed to transform underutilized food- and agriculture-derived resources into new ingredients and products that contribute to health and nutrition while also being conducive to a more sustainable environment.
Transforming by-products into co-products during wine production
Wine production is a sector where innovation can have a big impact. In 2018, 292 million hectolitres (one hectolitre equals one hundred litres) of wine were produced worldwide.
The process of winemaking involves crushing ripe grapes into grape must. For white wine, the must is then pressed to separate the juice from the solids. Next, the juice is fermented to produce wine.
The grape solids removed from the must are called pomace, or marc. Grape marc contains all the other components of the grape, including the skin, seeds, and pulp. Grape marc makes up the largest underutilized by-product from winemaking, with over 1.1 million tonnes generated in 2019 in California alone. Although a small amount of marc has traditionally been used to produce marc brandy or grappa, it is more commonly used as fertilizer or animal feed.
“Overweight or obese individuals may have improved insulin responses when consuming a blend of Chardonnay grape marc and seed extract.”
Collaborative research between Sonomaceuticals, LLC, the USDA Agricultural Research Service (ARS), and the University of California Davis (UC Davis) is providing exciting new insights into the potential benefits of co-products that usually go largely to waste in the production of Chardonnay wine. This multi-year program of collaboration is revealing new potential in Chardonnay marc co-products that can yield new food and dietary supplement ingredients having health benefits due to the concentration of certain naturally occurring compounds.
Potential bioactive components of Chardonnay grape marc
Sonomaceuticals is interested to better understand the use of Chardonnay grape marc to benefit human health. Dr Torey Arvik is involved in work which aims to valorize grape solids left over from winemaking. Valorization, a process that is gaining traction in numerous industries, simply means finding a better use for co-products, thereby reducing waste and enhancing value.
This has partly contributed to a new area of research which aims to explore the potential health benefits of bioactive components in Chardonnay grape marc.
Previous work by Dr Wallace Yokoyama, a scientist at USDA-ARS, compared the profiles of grape seed flours from different varieties to determine if there were different health impacts. Compared to other grapes, Chardonnay grape marc contained high levels of nutrients known as phenolics, with the highest levels found in Chardonnay seeds.
The team at Sonomaceuticals further explored the phenolic content of Chardonnay grape marc. They aimed to characterize the marc, with and without seeds, the seed alone, and an extract of the seed, to better identify the chemical composition of these winemaking co-products. The majority of phenolics in Chardonnay grape marc are the flavan-3-ols, including (-) epicatechin. Flavan-3-ols are compounds naturally present in plant-based foods such as grapes, tea, apples, and cocoa. Importantly, a number of research studies have shown that increased intakes of (-) epicatechin and other flavan-3-ols can have beneficial health effects on the cardiovascular system. Indeed, work from an international team of researchers, which included Dr Carl Keen and Dr Roberta Holt, observed that flavanol intake could improve vascular response and platelet function. Continued research on flavan-3-ols has convincingly demonstrated beneficial effects on the cardiovascular system. This may be due to their ability to affect a number of cellular signalling and metabolic pathways.
Aside from the flavan-3-ol content of marc, the Sonomaceuticals team were interested in the relatively understudied complex carbohydrate content of Chardonnay grape marc that can benefit gut health. This included the oligosaccharides, a type of fiber, known for their potential prebiotic benefits.
All Chardonnay marc samples analyzed contained abundant levels of flavan-3-ols, with the seed extract being the most concentrated phenolic. Thirty-six distinct oligosaccharides were discovered in the four samples. Whilst there was some overlap between the Chardonnay marc fractions, they each had their own individual oligosaccharide profile. These results demonstrate that Chardonnay marc could be a substantial dietary source of phenolics and oligosaccharides. Research is currently ongoing to determine the contribution of each of these Chardonnay grape marc components to health.
Potential health benefits of Chardonnay grape marc
Research by Dr Yokoyama identified ways that Chardonnay grape seed flour may benefit cardiovascular health in a series of studies using a rodent model. His group supplemented a high-fat diet with Chardonnay grape seed flour. This prevented the mice from gaining fat, despite consuming more food than the control group. The mice also had lower levels of a form of cholesterol often associated with increased cardiovascular risk, that is, low-density lipoprotein or LDL cholesterol. Moreover, Dr Yokoyama’s team were able to demonstrate that Chardonnay grape seed flour-induced changes in LDL were associated with changes in specific gut microbial populations and metabolites. Dr Yokoyama attributed these health benefits to the fiber and flavan-3-ol content of the Chardonnay seed flour. These results suggests that Chardonnay grape seed flour may benefit cardiovascular health in the management of obesity and obesity-related health effects that include improvements in cholesterol levels and gut health. However, further research, including well-controlled clinical trials, will be required to confirm the impact of these key Chardonnay grape marc components in humans.
Fanny Lee’s research is focused on exploring how pre-packaged capsules containing WellVine Chardonnay marc may affect the gut microbiome and cardiovascular health in humans. She and her collaborators have conducted initial trials examining the effects of Chardonnay grape flour and seed extract on cholesterol and insulin resistance. At this year’s meeting of the American Society of Nutrition, Ms Lee presented data suggesting overweight or obese individuals may have improved insulin responses when consuming a blend of Chardonnay grape marc and seed extract. While promising, further work is required to confirm these findings.
“Including Chardonnay marc in food products can potentially contribute to both public health and environmental sustainability.”
During the past several decades, much has been learned about compounds present in foods having bioactivity beyond that contributed by the currently recognized micro- and macro-nutrients. (-) Epicatechin, present in various plant foods, and specific oligosaccharides found in human breastmilk, are representative of these new discoveries. The cross-sector research collaboration between Sonomaceuticals, USDA-ARS, and UC Davis suggests Chardonnay grape marc is a food ingredient containing compounds that have this potential, including flavan-3-ols and oligosaccharides. Sonomaceuticals has already demonstrated that grape seed flour can be used in commercially available flours to enhance bread and other baked goods, and believes there is a potential for including Chardonnay grape marc in a wider variety of foods, beverages, and dietary supplements. In addition to the health and nutrition benefits associated with the compounds it naturally contains, inclusion of Chardonnay grape marc in these products contributes to environmentally sustainable viticulture and winemaking operations.