engleski

Production of high-value food ingridients from grape pomace

Grape pomace, the residue remaining after the extraction of juice from grapes is characterized by high content of polyphenols. In this study, we produced powder, a high-value food ingredient from grape pomace from indigenous grape varieties, White and Black Noah, Othello and Isabell. Grape pomace powder was produced by freeze drying of grape pomace. Obtained powders had the amount of water lower than 4 %. The water activity of powders was 0.237, 0.206, 0.201, and 0.198 for Black Noah, Isabell, White Noah and Othello, respectively. The highest antioxidant activity (mmoltrolox/100mL) had the powder produced from Isabell variety (4.82) followed by Black Noah (3.39), White Noah (3.29) and Othello variety (2.74). In the investigated varieties, the main phenolic acid was chlorogenic acid, the catechin was the representative of flavanols, and quercetin of the flavanols. In the red grape varieties the main polyphenol was cyanidine-3-glucoside, and malvidin-3-glucoside (known as natural colorants). The results suggest that grape pomace powders can be used as high-value ingredients to increase antioxidant activity and to enrich colour, and in general, phytonutrients content of processed food products.

freeze-drying ; polyphenols ; functional food

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