Analysis and extraction for polyphenols in apple juice of pre- pressing fruit

Using the apple juice of pre- pressing fruit as testing sample,the extracted and analyzed method of polyphenols in juice was optimized.The difference of polyphenols content between juice pressed pre- peeled and traditional process that pressed whole fruit was compared to show the advantages of pre- pressing fruit. The extracting condition of polyphenol was optimized using ultrasonic assisted extraction method and the method of polyphenols detection by HPLC also was optimized. The results showed that optimal extracting condition of polyphenol was temperature 50℃,time 40 min,ratio of juice to extracting 1 ∶ 3 and detection wavelength of HPLC was 280 nm,linear gradient elution compose of methanol and 0.3% acetate acid solution.The polyphenols separated result was best under the gradient elution condition which was determined in this test.So the polyphenol content in juice pre- pressing was decreased 23.62% as the category was same between traditional process and juice pressed pre- peeled method.The browning of the apple juice can effectively reduce in the new processing.