The physiological activities of 70% ethanol extracts of grape seed (GS) prepared by freeze-drying (GSFD), infrared drying (GSIR), hot-air drying (GSHD), or sun-drying (GSSD) were investigated. The moisture contents of GSFD, GSIR, GSHD and GSSD powders were 4.53, 6.71, 6.91 and 5.55% respectively. Hunter’s color value analysis revealed that the L* value of GSIR was lower, and the a* and b* values of GSIR were higher, than those of GSFD, GSHD, and GSSD. The total polyphenol and proanthocyanidin contents of GSFD were significantly higher than those of the other extracts. The flavonoid related substance contents were in the order of GSFD (7.68 g/100g) = GSSD (7.59 g/100g) = GSHD (7.33 g/100g) > GSIR (6.45 g/100g). The electron donating abilities of 500 μg/mL solutions of GSFD, GSIR, GSHD and GSSD were 88.71, 52.62, 65.20, and 65.22%, respectively, while their reducing powers (OD700) were 1.633, 1.097, 1.217 and 1.054 absorbance units, respectively. Additionally, the same trend was observed for the ABTS radical-scavenging abilities of the extracts as that observed for their electron-donating abilities and reducing powers. These results suggest that GSFD is the best method for preparing GS extracts with enhanced antioxidant activities, and that GS extracts may be used as a natural antioxidant material for use in health foods.

• 정다솜(대구가톨릭대학교 식품공학전공) | Da-Som Jeong
• 윤광섭(대구가톨릭대학교 식품공학전공, 대구가톨릭대학교 식품과학연구소) | Kwang-Sup Youn Corresponding author