Optimization of microwave-assisted extraction of polyphenolic compounds from Cabernet sauvignon grape skin pomace

Komina grožđa je visokovrijedan i bioaktivnim spojevima bogat nusproizvod dobiven tijekom proizvodnje vina. Cilj ovog rada je bio ispitati utjecaj polarnosti otapala (60 % i 100 % metanol), kiselosti otapala (0 % i 1 % HCl) te temperature (45 i 60 ˚C) na mikrovalovima potpomognutu ekstrakciju polifenolnih spojeva iz pokožice komine grožđa sorte Cabernet Sauvignon (Vitis vinifera L.) te odrediti antioksidacijski kapacitet dobivenih ekstrakata. Polifenolni sastav ekstrakata analiziran je spektrofotometrijskim metodama te metodom tekućinske kromatografije visoke djelotvornosti (HPLC), a antioksidacijski kapacitet utvrđen je fluorimetrijski (ORAC). Utvrđeni optimalni uvjeti mikrovalne ekstrakcije pojedinačnih grupa polifenolnih spojeva prisutnih u pokožici komine grožđa uz održavanje maksimalne antioksidacijske aktivnosti odnose se na primjenu 100 % metanola uz dodatak 1 % HCl pri temperaturi 60 ˚C u ekstrakcijskom vremenu od 16 minuta.Grape pomace in the valuable byproduct obtained during wine production, highly rich in bioactive compounds. The aim of this research was to examine the effect of solvent polarity (60 % and 100 % methanol), solvent acidity (0 % and 1 % HCl) and the process temperature (45 and 60 ˚C), on the microwave-assisted extraction of polyphenolic compounds from Cabernet Sauvignon (Vitis vinifera L.) grape skin pomace, and the antioxidant activity of the obtained extracts. Polyphenolic content of extracts was determined by spectrophotometry. Content of free anthocyanins was determined by HPLC, while antioxidant capacity of extract was determined by fluorimetry (ORAC). Optimal conditions in microwave-assisted extraction of total polyphenols, total tannins, total flavonols and total hydroxycinnamic acids as well for maintaining antioxidant activity showed to be 100 % methanol with the addition of 1 % HCl and temperature of 60 °C during 16 min