| 초록 |
Drying process was applied to increase the antioxidant activity of onion powder: freeze-drying or air-drying at 50, 70, and $90^{ circ}C$ and onion extracts were obtained from each powder using water or aqueous ethanol (50%) at $25^{ circ}C$ and $60^{ circ}C$ . In the color analysis, the freeze-dried powders showed higher $L^*$ and lower $a^*$ and $b^*$ values than did the air-dried ones. The browning index of powders air-dried at $90^{ circ}C$ was significantly higher than that of freeze-dried powders or those air-dried at temperatures below $90^{ circ}C$ . Phenolic content in the extracts was 4.02-23.12 mg gallic acid equivalent/g sample, and was the highest in the extract from the sample air-dried at $90^{ circ}C$ , regardless of the extraction condition. The highest antioxidant activity, measured by 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid and 1,1-diphenyl-2-picrylhydrazyl methods, was found in the powder air-dried at $90^{ circ}C$ , which induced browning. These findings indicate that antioxidant activity depends more on browning during drying than on extraction conditions. |
