Effect of enzyme, acid and combination applications as pre-treatment in cold pressed grape seed oil production

Grape cultivation, which has been going on for years in our country, has reached an advanced point, and it is of great importance to return to our economy tons of grape seeds that are released as waste in the plants where grapes are processed. Grape seed oil has become a widely preferred product in food, pharmacy and cosmetic fields due to the bioactive compounds it contains. In this study, various amounts (1-4%) of commercial enzyme preparate, acid and both of them were applied to grape seeds for three incubation periods of 12, 24 and 36 hours, and then the oil was obtained by cold pressing method. While an average of 8.13% oil yield was obtained from the control sample pressed without applying acid and/or enzyme, the highest oil yield was achieved in acid 4% 9.68% and enzyme 1% 9.51% treatments incubated for 36 hours after acid and enzyme treatments. In these treatments, an increase of 16.5-19% in oil yield was achieved compared to the control. The combined use of acid and enzyme did not provide as high a yield increase as when used alone. Negative effects of the enzyme in terms of yield, oxidative stability and bioactive component content were observed at 4% level and incubation for 36 hours. Acid application resulted in lower values in terms of free acidity compared to enzyme and acid + enzyme treatments. Enzyme addition provided high induction period in 12 and 24 hour treated samples. Higher total phenolics content and DPPH radical scavenging activity were obtained in 12 and 24 hour incubations at all levels of acid, enzyme and acid+enzyme pretreatments. In the 2.5% acid and 2.5% acid-enzyme treated samples incubated for 12 hours, there was an increase of 65 and 62% in the phenolic component content, respectively, compared to the control. Since grapes are widely produced in our country and cold press extraction has a low cost, is easy to use, and has gained the trust and popularity of consumers in recent years, it has provided an advantage of use in the food industry. Keywords: Grape seed, grape seed oil, cold press, enzyme, acid