Phenolics profiling of pomace extracts from different grape varieties cultivated in Argentina

Abstract

Grape pomace can be considered as an excellent and inexpensive source of phenolic compounds with potential bioactive properties. Therefore, the key aim of this study was to carry out a comparative study of different Argentinean grape varieties for selecting the most convenient residue during the recovery of compounds with antioxidant activities that will be useful in emerging industrial applications. Phenolics, including 17 non-anthocyanins and 13 anthocyanins, isolated from grape pomace (GP) obtained from the varieties Malbec, Cabernet Sauvignon, Cabernet Franc, and Merlot, were characterised via assessing different chemical profiles of the studied samples. The maximum concentrations of the non-anthocyanins corresponded to the following flavanols: (−)-epicatechin (5518 μg g⁻¹), (+)-catechin (5340 μg g⁻¹), procyanidin B1 (1820 μg g⁻¹), and syringic acid (6665 μg g⁻¹). Malvidin-3-glucoside was the most abundant anthocyanin (32 056 μg g⁻¹). The compound OH-tyrosol was first identified and quantified in the GPE of Cabernet Franc and Malbec. Moreover, stilbene trans-resveratrol was found at the levels as high as 328 μg g⁻¹ GPE in Malbec, thus highlighting the potentiality of the variety as a source of compounds with nutraceutical value. A discussion about the relationship between the high levels of syringic acid and the anthocyanin malvidin-3-glucoside has also been presented. Based on the results, new knowledge for understanding the possible synergic effects between the contents of compounds of different families in the extracts was presented. This information can be helpful for the technological application of the extracts and to justify different beneficial effects achieved when these extracts are used in experimental models.