Comparison of the antioxidant activities of sulfur-fortified onions stored at room temperature and 1°C

초록

Sulfur-fortified onions were stored at two different temperatures, room temperature (RT) or 1°C, for up to 20 weeks post-harvest. Attributes relating to quality and antioxidant activities were compared between the two groups over time. No significant difference in the hardness and color of the onions, stored at the two different temperatures, was observed throughout the time in storage. At 20 weeks of storage, onions stored at RT showed significantly (P<0.001) higher moisture content and lower carbohydrate and soluble solid content, compared to the onions at 1°C. This was presumably due to a faster respiration rate at a higher temperature. With increasing time in storage, the total flavonoids, superoxide dismutase-like activity, and metal-chelating activity increased significantly, which was independent of the storage temperatures. Total reducing capacity that reflects both phenolic and non-phenolic antioxidant content remained constant during the 20 weeks of storage, which was again independent of the storage temperatures. However, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity decreased appreciably at 20 weeks in the onions stored at 1°C. This was not the case with the onions stored at RT. This could be attributed to the loss of non-phenolic antioxidants such as vitamin C which has superior hydrogen donating ability. These results show that storing onions under optimal post-harvest conditions increased their antioxidant activity and reduced storage cost. © 2020 Korean Society of Food Science and Nutrition. All rights reserved.

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