| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 98 === The objective of present study is to purify and characterize the tyrosinase inhibitor from rose in order to provide information for its application in food or cosmetics.
Tyrosinase inhibitor from rose was extracted by various solvents and compared to its recovery for tyrosinase inhibition. Among them, methanol showed the best efficiency, followed by ethanol, water, hot water, hexane, and ethyl acetate. The optimum extraction time was 2 hours. The concentration caused 50% inhibition (IC50) was 0.048±0.00μg/mL and recovery was 20.93 ± 0.05%.
The optimal conditions for extracting tyrosinase inhibitor from rose by using supercritical fluid extraction (SFE) are listed in the following: pressure, 450 bar; temperature 60 ℃; carbon dioxide flow rate, 4 L / min; extraction time, 20 minutes for static and 10 minutes for dynamic extraction; modifier, 3% in static extraction; flow rate of modifier, 2 mL/min in dynamic extraction.
Crude extract of tyrosinase inhibitor from rose was then partially purified with Si and C18 gel fractionation. Two active fractions were obtained from the above separation, and named RES & RES-4 respectively. The recovery was 36.60 ± 0.74% and 7.25 ± 0.01%, IC50 was 0.036±0.00μg/mL and 0.026±0.00μg/mL. Kinetics study showed RES-4 belonged to a competitive inhibition. RES-4 possessed the ability to reduce Cu(II) into Cu(I) but had no ability to reduce dopaquinone.
Shrimps presoaked in 100 ppm or 200 ppm of tyrosinase inhibitor from rose for 30 minutes or 60 minutes could prevent from darkening whether stored in 4℃ or 25℃.
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