This study determined the antioxidant levels and activities of hot water aronia extracts by different drying methods such as sun drying, sun drying after steam treatment, freeze-drying, and oven drying. The total polyphenol content, calculated as gallic acid equivalent, was the highest in the freeze-dried sample (910 mg), followed by sun-dried after steam treatment (779 mg), sun-dried (769 mg), and oven-dried (757 mg) samples. Similar patterns were observed for the total flavonoid and anthocyanin contents. Freeze-dried aronia samples contained the highest polyphenol, flavonoid, and anthocyanin contents as compared to the samples dried by other methods. All antioxidant activities were found to increase in a dose-dependent manner. For the hot water-extracted freeze-dried aronia powder (200 mg/mL), the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radicalscavenging activities were 65.5% and 61.7% and the hydroxyl and superoxide anion radical-scavenging activities were 50.5% and 52.1%, respectively. These results suggest that comparatively, freeze-drying is a better method for preserving the bioactive components and the antioxidant activities of aronia.
We investigated the quality and antioxidant activities of sponge cake prepared containing 1-5% of green tea powder (GT). The water content in the cake increased with an increase in the amount of GT added. Although the hardness and springiness of the rice sponge cake increased, the adhesiveness decreased with increasing the level of GT. The cohesiveness, chewiness, and resilience of the rice sponge cake with GT were similar to those of the control. Chromaticity determination revealed that lightness, redness, and yellowness of the crust decreased with increasing GT content. Total polyphenol and flavonoid contents increased proportionally with increasing GT level. Antioxidant activity, measured by DPPH and ABTS radical scavenging as well as reducing power activities, was significantly higher in the rice sponge cake with GT than in the control. Sensory evaluation determined that addition of 1-3% GT to the rice sponge cake maintained the color, taste, texture, flavor, and overall acceptance similar to that of the control.
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