Hypoglycemic Activity Of Lemon Peel Polyphenols In Vitro And Development Of Polyphenol Yogurt

Citrus peel is rich in polyphenols,which have antioxidant,bacteriostatic,hypoglycemic and lipid lowering effects.Citrus limon’Rosso’,as a Citrus fruit,has a special aroma and thick peel,which is conducive to the extraction of polyphenols.In this paper,the polyphenol extract of perfume lemon peel from Hainan Province was taken as the main research object to explore its in vitro hypoglycemic activity,analyze its components,and finally develop a sugar-free lemon polyphenol yogurt,so as to develop the residual value of lemon processing by-products and improve the overall economic benefits of lemon.(1)Analysis of polyphenols in lemon peelThe total scanning of polyphenols in lemon peel by UV-Vis spectrophotometer at 200-700nm showed that the maximum absorption peak existed at 320 nm,which was consistent with the characteristic absorption band of polyphenols.Twelve polyphenols were analyzed by HPLC-QTOF-MS,which were as follows:4-Methylumbelliferyl b-D-glucuronide dihydrate,Vanillic acid,Neochlorogenic acid,Orientin,Kaempferol 3-O-Glucorhamnoside,Eriocitrin,Rhoifolin,Scoparin,Diosmin,Hesperidin,Chrysoeriol-7-O-(2’-O-mannopyranosyl)allopyranoside and Nomilin.Qualitatively and quantitatively,Hesperidin is the main component of lemon peel polyphenols,the content is 71.93±0.29μg/mg;secondly,the contents of diosmin and saintoside were 35.19±0.45μg/mg and 23.88±0.23μg/mg.(1)Study on the hypoglycemic activity of lemon peel polyphenols in vitroThe hypoglycemic activity of Lemon Peel Polyphenols(LPP)was investigated by establishing insulin resistance Hep G2 cell model.The results showed that LPP could increase the glucose consumption of IR-Hep G2 cells by 15.1%at most.The glycogen content and the activity of glucose metabolism related enzymes in IR-Hep G2 cells were measured.Compared with the model group,the glycogen content of IR-Hep G2 cells treated with 0.5 mg/m L LPP increased by 0.09 mg prot/m L.The activities of hexokinase and pyruvate kinase were increased by 12.36 nmol/min/mg prot and 16.11 U/g prot.The activities of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase were decreased by 8.15 IU/g prot and 4.07 IU/g prot.(3)Preparation of lemon polyphenol yoghurtThe formula and process of lemon polyphenol yoghurt were optimized by single factor and response surface test.The optimal conditions were as follows:Xylitol added 6.9%,lemon crude polyphenol added 0.19%,fermentation temperature 41.9℃,fermentation time 4.9 h,the finished lemon polyphenol yogurt fine texture,palatability,in line with the public taste,the acidity of84.8±0.96°T,fat content 3.5±0.05 g/100 g,The solid content of non-fat milk was 12.5±0.09g/100 g,the protein content was 3.2±0.03 g/100 g,the total number of lactic acid bacteria was≥3×10~6 CFU/m L,which all met the national standard,and the active ingredient LPP in yogurt could be retained 76.2%after fermentation.It was found that the main component of lemon peel polyphenols was flavonoids,which could improve the absorption and utilization of glucose by promoting glycogen synthesis,increasing the activities of hexose kinase and pyruvate kinase,and reducing the activities of glucose-6-phosphatase and phosphoenolpyruvate carboxyl kinase,thereby alleviating insulin resistance and further exerting hypoglycemic activity.In this paper,lemon peel polyphenols yogurt was prepared by combining the beneficial effects of yogurt and lemon peel polyphenols,which opened up a new way for the application of lemon peel polyphenols.