Enzymatic biotransformation of polyphenolics increases antioxidant activity of red and white grape pomace

Authors: MARTINS, ISABELA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; ROBERTO, BRUNA - Universidade De Campinas (UNICAMP); BLUMBERG, JEFFREY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; CHEN, CHUNG-YEN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; MACEDO, GABRIELA - Universidade De Campinas (UNICAMP)

Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2016
Publication Date: 9/7/2016
Citation: Martins, I., Roberto, B.S., Blumberg, J.B., Chen, C., Macedo, G. 2016. Enzymatic biotransformation of polyphenolics increases antioxidant activity of red and white grape pomace. Food Research International. 89:533-539.

Interpretive Summary: Agroindustrial wastes derived from food productions, e.g. almond skins generated from almond blanching and grape pomace from wine production, have become a value-added product mainly due to their rich contents of beneficial phytochemicals. For example, they can be used for the development of nutraceuticals and functional foods. Phytochemicals in grape pomace have a potential for diverse applications. For instance, they can be used as antioxidant additives, natural colorants, or food preservatives; they can also be formulated into functional foods, nutraceuticals, and cosmetics. Grape pomace derived from wine production contains appreciable amounts of phytochemicals, including flavonoids and phenolic acids. However, phytochemicals in grape pomace may not have reached their maximum health efficacy potential because they are tightly bound to cellulose matrices. In order to enhance their absorption after consumption, treatment with enzymes (e.g. pectinases, cellulases, and glucanases) has been employed to liberate them from the matrices. As enzymes may differ in hydrolysis efficacy and may produce distinctive composition profiles, the objective of this study was to examine the impact of tannase, pectinase, and cellulase on the hydrolysis of polymeric polyphenols in red pomace, white pomace, and a mixture of grape pomaces from the wine production, as well as antioxidant activity of the hydrolyzed products. We found that the contents of the grape pomace and the antioxidant activity of phytochemicals in grape pomace are subject to the influence of the grape pomace source and enzyme treatment. Among the 3 grape pomaces examined in this study, we found red grape pomace contained the highest amount of polyphenolics and displayed the most potent antioxidant activity. We also found that tannase displayed the largest hydrolytic efficacy. Therefore, grape pomace, a byproduct of wine production, is a value-added waste because of the presence of polyphenolics and possibly for other reasons, as well. Further studies are warranted to develop functional foods, nutraceuticals, or cosmetics using grape pomace containing a high amount of polyphenolics.

Technical Abstract: Grape pomace (GP) is a polyphenolic-rich byproduct of wine production. As most polyphenolics are either bound to cellular matrices or present as free polymeric forms, treatment with hydrolytic enzymes may act to increase GP functionalities. The aim of this study was to examine the impact of tannase alone (T), pectinase plus cellulase (PC) or a mixture of them (TPC) on the hydrolysis of polyphenolics in red GP (RGP), white GP (WGP), and mixed GP (MGP) from Brazilian wine production, as well as antioxidant activity of the products. T was the most potent in increasing total polyphenols in GP by liberating gallic acid, caffeic acid, quercetin, and trans-resveratrol. PC increased the catechin content in RGP and TPC increased the procyanidin B2 in WGP. T treatment of GP was most effective in increasing antioxidant activity. In conclusion, the enzymatic treatment, particularly with T, increases the polyphenolic content and antioxidant activity of GP.