By-products of the wine supply chain are leading the way in innovation, under the banner of the circular economy. The pomace is the focus of a wide-ranging project to enhance it as a superfood and super-feed, among other things. New opportunities for a country like Italy, which for the fourth consecutive year is confirmed as the leading global wine producer. (1) And so, of by-products of winemaking.
A treasure trove of scraps
Vinacce and other by-products of winemaking have always represented an additional cost to businesses for proper disposal. But this aggravation could instead turn into a source of income.
The most interesting wastes, as they are characterized by the presence of substances useful to the food and cosmetics industries, are the pomace, that is, the skins of the pressed berry that still contain the seeds (grape seeds), the grape seeds themselves and the stalks (the woody part of the bunch). But research is advancing, and other processing residues are also finding a place in virtuous recovery.
Cellar wash water (wastewater), for example, is the focus of a project to use it along with lees as biomass for electricity generation and hydrogen recovery in a ‘bio-refinery.’ (2)
The lees – i.e., the sediments of fermented liquids that remain in the barrels where the wine is placed to age or ferment – are, moreover, already of commercial value, with a view to reuse in the production of tartaric acid, as well as aqua vitae (grappa in Italy, cognac in France).
Vinacce in baked goods
The destination of pomace is increasingly geared toward incorporation into foods, to which they contribute fiber and antioxidants of undoubted nutritional and health value. Researchers at theUniversity of Life Sciences of Poznań, Poland, conducted a study to evaluate the nutraceutical and sensory effects of adding white grape pomace into wheat flour for cookie production. Three tests were performed, incorporating 10, 20 and 30 percent pomace into the flour, respectively.
The best combination to increase the presence of antioxidant polyphenols is the addition of 30 percent pomace. With this mix, phenolic compounds in the cookies increased from 0.11 to 1.07 mg. The best result in terms of palatability, conversely, was achieved with 10% supplementation. Which in itself is worth almost doubling the total fiber content (+88%).
Pomace in yogurt
Probiotics and pomace is a combination considered ideal for amplifying the benefits of yogurt consumption by incorporating fiber and antioxidants. Several scientific studies have verified the viability of this option. Most recently, work conducted by researchers at two Italian universities (Turin and Bra) also tested consumer preferences for super-yogurt.
The researchers added pomace unfermented from three different cultivars (Chardonnay, Muscat and Pinot Noir) to a whole yogurt. Which, after three weeks of storage at 4 °C, showed a significant increase in antioxidant content – with no negative impact on probiotics – compared with the same yogurt without supplementation. (2)
From an organoleptic point of view, yogurt fortified with Pinot noir pomace (ranked first in antioxidant content) failed the test of the 256 regular yogurt consumers who tried it. Better was the other two super-yogurts with white grape pomace, although there is a need for further improvement.
The tasters negatively judged the excessively sour taste of the yogurt and the excessive grain perception of the pomace mince. Leading researchers to converge on the desirability of reducing the pomace grain size and modifying the flavor by adding sweeteners or employing a yogurt with lower acidity.
Grape marc, a natural antimicrobial
Further uses of the wastes that result from wine production aim to enhance their antimicrobial and antioxidant virtues. With a view to replacing synthetic preservatives, which are often suspected of toxicity.
Phenolic compounds grapes, not completely extracted by crushing, remain in the marc and give them an effective action in inhibiting the growth of microorganisms (including pathogens), with the valuable result of counteracting fat oxidation. In a perspective of great interest for the food industry, as revealed by thea review conducted by a team of Brazilian researchers from the ‘Rural Federal University of Rio de Janeiro‘ and Embrapa, a public research company on sustainable agricultural development.
Grape marc in feed, a ‘super-feed‘ with functionality on milk and cheese as well
The virtues of the pomace extend to the livestock supply chain, with favorable cascading effects on derived products. This is the finding of the research of the University of Teramo, which evaluated the nutritional properties of milk and cheese obtained from Friesian cows in whose diet dried pomace was included.
The Teramo study highlights the overall improvement in the nutritional profile of food obtained from the milk of Friesians fed with ‘super-feed‘. With increased oxidative stability in cheese, after 30 days of ripening, increased linoleic acid concentration. About ‘super-feed‘ with impact on fat quality, the positive experience of the Ferri group in Castelvetro is recalled. In this case-thanks to a diet that includes herbs and acorns-the operator was able to obtain meat with Omega-3 (‘Nature Care’) .
Bioplastics and fabrics
The circular economy applied to agriculture reaches a pinnacle of innovation in the use of by-products to make biopolymers, bioplastics and yarns. New natural materials and alternatives to hydrocarbon-derived plastics to solve the plastic and microplastic pollution crisis at the source. Research and development in Italy is advancing, as has already been seen with textiles from citrus fruits and bioplastics from mowing and other plant wastes. As well as those from hemp, tomato and oranges.
The Italian start-up Vegea of Rovereto (Trento), thanks to European funding and some sponsors, has transformed grape skins, seeds and stems into a textile product, which has been awarded as an example of circular economy. With some peculiarities compared to ‘traditional competitors’, leather and ‘faux leather’ (i.e. plastic). Fabric from grape pomace, in addition to being ‘vegan,’ does not employ or contain polluting chemicals.
Grape seed oil
Grape seeds – the small seeds stored in grape berries – are another source of enhancing the by-products of winemaking. The oil made from it is highly valued in both cosmetics and nutrition. Particularly for its high concentration of linoleic acid, an essential fatty acid of the Omega-6 group. The health benefits of which are associated with the right balance with Omega-3 fats, which finds ideal synthesis in hemp oil.
The refined grape seed oil is valued for its high smoke point, making it suitable for frying and cooking at high temperatures. However, common high-temperature refining processes remove some of the bioactive substances (zeaxanthin and β-carotene) of particular nutritional value. Thus, where employed in the diet, it is preferable in the ‘virgin’ version. According to the study conducted by a team of Brazilian researchers on the properties and stability of organic grape seed oil.
The best extraction technique of oil from grape seeds is the use of supercritical CO2. A nontoxic, low-temperature process, as already explained, but expensive. A Croatian research team used this ‘environmentally friendly solvent’ to extract oil from grape seeds. Experimentation has shown that by using a pressure of 400 bar and a temperature of just 41°C, complete extraction of the oil is achieved, preserving its α-tocopherol (vitamin E) content.
Marta Strinati
Notes
(1) In 2018, Italian wine production increased by 10.5 percent to 50.4 million hectoliters, 17 percent of global production. The world’s leading wine producer, the Bel Paese also holds the world record for the number of certified wines (PDO and PGI), a total of 523 (against France’s 435, its eternal rival). Il Sole 24 ore data https://www.ilsole24ore.com/art/impresa-e-territori/2019-04-03/il-vino-italiano-fattura-11-miliardi-italia-primo-produttore-mondiale-155303.shtml?uuid=ABAdqbkB
(2) See the project BIOVALE – BIOrefinery: Added Value of Oenological Byproducts, supported by Ager http://www.progettoager.it/index.php/le-news-progetto-ager/biovale-trasformare-in-risorse-gli-scarti-della-vinificazione
(3) The pomace, supplied by a winery in Fontanafredda, Alba, was mechanically separated, stored at -20 °C, dried at 54 °C for 48 hours, ground to a particle size of less than 250 μm, and finally autoclaved at 121 °C for 15 minutes before being added to the yogurt
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
