| A rose is a flowering plant with medical and nutritional values.It contains a variety of active substances and has beneficial health care properties.Polyphenols and other active substances are the main functional components of rose,which are a kind of natural antioxidant and have high application value in food,medicine,cosmetics and other industrial fields.At present,the high value utilization rate of rose is low.It has broad application prospect and important practical significance to extract and utilize polyphenols in rose for the development of high added value products of rose.In this paper,the double petal rose"Fenghua no.1",which is abundant in Hengshui City,Hebei Province,was used as raw material.The polyphenols were extracted by ultrasonic assisted Deep eutectic solvent(DES),and purified by macroporous adsorption resin.Rose polyphenol-chitosan particles were prepared and their antioxidant and hypoglycemic activities were studied.The main research contents are as follows:1.The rose polyphenols were extracted using deep eutectic solvent(DES)with ultrasonic-assisted technology from the double rose"Fenghua No.1",abundant in Hengshui City,Hebei Province.The traditional ethanol extraction method was also applied to extract rose polyphenols in comparison.The optimal extraction conditions of rose polyphenols by DES method were as follows:choline chloride lactic acid(molar ratio 1∶2)with 30%water content was the best extraction agent,the solid-liquid ratio was 1∶40,ultrasonic time was10 min,ultrasonic power was 400 W,ultrasonic temperature was 50℃,and extractions were completed two times.Under these conditions,the amount of polyphenols extracted was(136.20 mg/g(dried flower).Compared with the ethanol extraction method,the number of polyphenols extracted by DES was increased by 24%.2.Five kinds of macroporous adsorption resins were used for the separation and purification of rose polyphenols.The most suitable resin for the separation and purification of rose polyphenols was selected as NKA-9.The results of static adsorption and desorption conditions were optimized as follows:the water content of the absorbed rose polyphenol extract was 40%,and the volume fraction of ethanol was 70%as the desorption solution,and the purity of rose polyphenol was 88.5%.3.Antioxidant and hypoglycemic activities of rose polyphenols were investigated.In vitro antioxidant test results showed that the total reducing power and DPPH free radical scavenging ability of the rose polyphenols were similar to VC.Furthermore,ABTS~+free radical scavenging capacity was higher than that of VC.In order to improve the stability of rose polyphenols,rose polyphenol-chitosan particles were prepared,and the optimal preparation conditions were optimized as follows:Under the conditions of chitosan and sodium tripolyphosphate mass ratio(CS/TPP)of 2:1,acetic acid concentration of 0.5%and rose polyphenol concentration of 3 mg/g,the encapsulation rate of rose polyphenol was 94.85%and the loading rate of rose polyphenol was 21.26%.Stability experiments showed that rose polyphenols-chitosan particles were more stable than rose polyphenols under light and air conditions.The results showed that both rose polyphenol and rose polyphenol-chitosan granules could slow down the weight loss,decrease fasting blood glucose and improve oral glucose tolerance in mice.It increased the activities of Superoxide Dismutase(SOD)and Glutathione peroxidase(GSH-PX)and decreased the content of malondialde-hyde(MDA)in mice.These results indicated that both rose polyphenol and rose polyphenol-chitosan had good antioxidant and hypoglycemic activities.In conclusion,ultrasound-assisted DES method is an efficient and environmentally friendly extraction method for rose polyphenols.Rose polyphenols have good antioxidant and hypoglycemic effects,providing theoretical basis for the high-value utilization of rose. |
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