Studies On Extraction Of Polyphenol Compounds From Apple Juice And Their Biological Activities

In this dissertation, the contents of total phenolics, chlorogenic acid, flavanols and proanthocyanidins in nine apple varieties, including Qinguan, Fuji, Gala, Huaguan, Huashuai, Golden Deliciou, Rails, Redchief Delicious and Granny Smith, were determined during development of fruits firstly. The process for extracting polyphenol compounds from apple juice was designed by resin screening and optimizing the condition of absorption and desoption. Finnaly, the bioactivities of apple polyphenol extracts made according to the process were studied.The results pointed to great quantitative differences in polyphenols composition and contents in the flesh of various apple varieties. The contents of total phenolics, chlorogenic acid, flavanols and proanthocyanidins in apple fruits fell sharply during early stage of development, and then decreased slightly or inclined to constant. It was suggested that Granny Smith was a better variety for production of apple juice and immature fruit was the best for extraction of polyphenol compounds according to the polyphenol content.XDA-5 resin was exellent for extraction of polyphenol compounds from apple juice, and the optimum absorption temprature was 40 C, 80% ethnol solution was better for desorption. The optimal process for extracting polyphenol compounds from apple juice was: Apples were crashed with repellent, and the juice were heated to inactive PPO after pressing immediatelly; Clarified juice obtained following enzyme treatment, clarification and ultrafilatration were adsorbed with XDA-5 resins; Resins were desorped with 80% ethnol solution, and apple polyphenol extratcts were obtained by concentrating and drying the washing-out solution at hypobaric conditions. This process not only can improve the quality of apple juice concentrate, but also utilize the resources sufficiently. The total phenol content of apple polyphenol extracts made according to the process came to 96.72%, the content of chlorogenic acid, flavanols and proanthocyanidins was 20.76%, 70.58% and 62.26% respectively.The apple polyphenol extracts had stronger reducing capacity, antioxidant activity on lipid-peroxidation, and scavenging effects on hydroxyl radical, superoxide anion radical and nitroso than ascorbic acid at the same concentration. In the range of test concentration, the maximum scavenging or inhibition rate of apple polyphenol extracts to linoleic acid auto-oxidation, nitroso, hydroxyl radical generated by Fenton reaction, superoxide anion radical generated by illuminating riboflavin and pyrogallol auto-oxidation was 94.4%, 95.76%, 96.64%, 95.19% and 90.48% respectively. The results suggested that the apple polyphenol extracts was an excellent natural antioxidants, free radical and nitroso scavenger. And they also proved that the process designed in this dissertation could maintain the bioactivities of apple polyphenols.