Identification and characterization of vitamin E isomers, phenolic compounds, fatty acid composition, and antioxidant activity in seed oils from different muscadine grape cultivars

Abstract

To investigate the values of muscadine grape byproduct, seed oils from 48 muscadine grape cultivars harvested in two seasons were evaluated for their vitamin E isomer content and fatty acid profile. The polyphenol profile and antioxidant properties of the oils were investigated from selected muscadine cultivars. The results showed that muscadine grape seed oils (MGSOs) contained 584.7 mg/kg tocopherols and 517.6 mg/kg tocotrienols, higher than those in other common edible oils. More than 85% of the fatty acids in MGSOs were unsaturated, dominated by linoleic acid. The vitamin E isomer contents were positively correlated with percent linoleic acid in MGSOs which also contained large amounts of phenolic compounds ranging from 124.79 to 358.04 μg/g oil. In addition, MGSOs possessed strong antioxidant activities, which were correlated with the γ-tocopherol and total polyphenol contents in the oils. Collectively, these studies demonstrate that MGSOs are edible oils with great nutritional potential. Practical applications This study presents the identification and characterization of vitamin E isomers and phenolic compounds in seed oils from different muscadine cultivars. The information is highly relevant to the ever-increasing need for natural, renewable sources of nutraceuticals among consumers. The study also shows high contents of tocotrienols and phenolic compounds in the oils, which could lead to a health claim and added value for muscadine processors and growers.