Influence of thermal processing on physicochemical properties and fatty acid composition of grape seed oils

In this study, the oils from four different grape seed varieties were heat-treated at 40 and 80 °C for 30 minutes to determine the changes in physicochemical properties and fatty acid composition. Overall, the heat treatments increased the peroxide value and free fatty acids in the oils. The highest total phenolic content values (from 259.67 to 524.77 mg GAE/kg) for all varieties were detected at the control temperature and decreased after both heat treatment applications. Likewise, to total phenolic content and antioxidant activity of the grape seed oils decreased significantly as the temperature applied increased. The dominant fatty acid in all varieties was detected as linoleic acid (from 71.10 to 72.09%), followed by oleic (from 14.55 to 16.64%) and palmitic (from 7.45 to 8.64%) acids. Considering the effect of heat treatment on the major fatty acids, the increase in temperature caused a small decrease in linoleic acid values and a more significant increase in oleic acid values.