Grape seed oil volatiles and odour activity values: a comparison with Turkish and Italian cultivars and extraction methods

Valorization of bioactive-rich wastes of food industry, such as grape seeds, is one of the most popular topic worldwide. The present study is designed to examine the volatiles of grape seed oils obtained by two Turkish (cvs. Okuzgozu and Emir) and two Italian (cvs. Sangiovese and Moscatello) cultivars by using two well-known oil extraction methods, cold percolation (CP) and soxhlet (SX). In order to evaluate their volatile composition, obtained oil extracts were subjected to purge and trap aroma extraction chamber combined with gas chromatography–mass spectrometry GC–MS. Revealed results showed that the oil yield, volatile compositions and odor activity values (OAVs) of grape seed oils altered depending on both variety and extraction method of the oil. According to results, a total of 60 and 67 volatile compound were detected in CP and SX aromatic extracts. High temperature applied during SX led to form new volatiles and increase in overall volatile composition due to oxidation reactions. Among all aroma groups, alcohols were the dominating aroma group followed by esters in each cultivar for both extraction methods. GSOs obtained by red grape varieties exhibited apparently higher ester concentration while white varieties were abundant in terpenes. Additionally, SX method caused to form some heat derived volatiles. Moreover, a total of 26 and 33 aroma compounds possessed OAVs greater than 1 and ethyl octanoate (sweet-apple odour), nonanal (fatty-citrus odour) and 1-octen-3-ol (mushroom, earthy odour) were found to be dominant volatiles with respect to their OAVs.