Grape by-Products: Potential Sources of Phenolic Compounds for Novel Functional Foods

Abstract

Grapes occupy an important position in the human diet, providing both macronutrients and micronutrients indispensable for growth and development. Grapes contain enzymatic and non-enzymatic (nutritional) antioxidants, such as ascorbic acid and bioflavones. High amounts of these valuable compounds are removed through processing, when the skin and the seeds are separated from the pulp. During the vinification process, a large amount of grape pomace is generated that constitutes an important source of value-added products such as phenolic compounds, mainly flavonoids, phenolic acids, and stilbenes. Valorization of wine industry by-products like grape pomace is a suitable strategy for recovering bioactive compounds (mainly polyphenols) and reducing the environmental impact of this industrial waste. The circular bioeconomy refers to maintaining the value of the biological resources in economy for as long as possible, minimizing the waste production. Recovery and utilization of pomace from grape process favors closing the loop to ensure the abovementioned circularity. The experimental screening performed was designed to assess several indices of the polyphenolic composition of several grape byproducts (pomace, steams, and skin and seed mixture), such as total polyphenolic content, total flavonoid content, and their antioxidant activity, for two white grape Romanian varieties (i.e., Fetească Albă and Tămâioasă Românească).