| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 99 === The purpose of this research was to clarify the antioxidant activity of Ulva clathrata water soluble extractives. The maximal polysaccharides contents were extracted by adding one hundred volumes of de-ionized water to original algae weight, and heating at 100oC for 1 hour. The hot-water extractives by acid and base treatment or precipitation used adding four volumes of 95% ethanol. Each extractive from Ulva clathrata was hydrolyzed by enzyme. The tentative compositions and antioxidant activities of extractives were determined, respectively. According to results, it show that reducing power, chelating Fe2+ effect, scavenging of DPPH and Trolox equivalent antioxidant capacity of each extractive were increase as concentration increase. After acid and base treating, the reducing power and chelating Fe2+ effect of extractives were better than hot-water extract only. Each extractive from Ulva clathrata hydrolyzing with α-amylase or cellulase, it showed the reducing sugar content of later was more than former; and the antioxidant activity of cellulase treatment group exhibited the best among other groups. Therefore it supposed that the antioxidant activity of water soluble extractives of Ulva clathrata was offered by degradation of its polysaccharides.
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