Application of grape pomace and stem extracts on Vitis vinifera L. cv. Monastrell: Increased stilbene content of grapes and wines

Abstract

Pomace and grape stems are the main solid organic waste from winery industries, resulting from the pressing and/or fermentation processes it is generated in large amounts in many parts of the world, and disposed of in open areas causing environmental and economic problems.1,2 Therefore, it is necessary to look for alternatives to revalue these bioproducts, making the winemaking process a more sustainable activity. Therefore, this work aims to determine whether grape pomace extracts can be used as elicitors to increase the biosynthesis of healthy compounds in wine grapes.The experiment was carried out in 2021. Two polyphenolic extracts were obtained: one from pomace and the other from grape stems. Subsequently, the extracts were sprayed on Vitis vinifera L. cv Monastrell at the beginning of veraison (1st application) and seven days later (2nd application). When grapes reached technological maturity, they were harvested and transported in boxes to the winery for physicochemical analysis and vinification. Wines were analyzed at the end of alcoholic fermentation.The results indicated a significant increase in the concentration of grape stilbenes, especially by treatment with pomace extracts. The following stilbenes were increased: T-piceid, piceatanol, C-piceid, T-resveratrol and viniferins. The wines produced also showed a higher concentration of stilbenes compared to the wines from control grapes; mainly T-resveratrol and viniferins were released into the wine.In this sense, stilbenes are of particular importance in plants as they are synthesized under biotic or abiotic stress, giving the plant greater resistance to fungal attack.3 On the other hand, resveratrol has been extensively studied for its importance in health, as it is attributed with antioxidant, anticarcinogenic, neuroprotective and cardioprotective properties.4 Therefore, these results show that the use of pomace and grape stem extracts are a very interesting alternative since they would allow: revaluing the winery’s bioproducts, reducing the use of synthetic pesticides and increasing the functional value of grapes and wines.

References

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