Preparation And Study Of Three Different Polysaccharide-sodium Alginate-tea Polyphenol Sustained-release Microcapsules

Tea has physiological functions such as anti-tumor,anti-oxidation,anti-bacterial,anti-radiation,hypoglycemic,hypolipidemic and enhanced immunity.This is related to the tea rich in tea polyphenols,caffeine,tea polysaccharides,tea pigments and theanine closely,and so on.Among them,tea polyphenols are one of the main components that form the color,aroma and taste of tea,and are also the main ingredients that make tea have health care functions.Because tea polyphenols have a variety of biological regulation functions,it is a research and development hotspot in the fields of food,medicine,daily chemicals and feed,and has capacious applied foreground.However,the tea polyphenols'stability is poor,and their structure contains a large amount of active phenolic hydroxyl groups,which are easily degraded in neutral and alkaline environments;oxidative polymerization and heterogeneity are also likely to occur under unfavorable environmental conditions such as high temperature,humidity and light,the reaction is such that the original biological activity changes,so the bioavailability is low in the unprotected state.Microcapsule technology is an effective method to improve the stability of tea polyphenols.The tea polyphenol microencapsulation uses a natural or synthetic polymer material as a wall material,and core material is tea polyphenols,which is embedded into microcapsules.The embedded tea polyphenol can maintain its physiological activity,stability,increase its sustained release and reduce the amount of use.Therefore,it is of great significance to protect,store and apply tea polyphenols by t microcapsule technique.In this paper,the core material is tea polyphenols,and sodium alginate is used as the base material,three kinds of polysaccharides with different charge properties--gum arabic powder,inulin,and chitosan,are used as the composite wall materials,and used CaCl₂ as a fixing solution,on this basis,tea polyphenol microcapsules were successfully prepared.The overall and surface local structure of the microcapsules were investigated by scanning electron microscopy.The quality of tea polyphenol microcapsules prepared from different wall materials was evaluated.The effects of different compound wall materials on tea polyphenols embedding rate,in vitro digestive release and storage stability were studied.The main research contents and results are as follows:?1?The microcapsules prepared by the extrusion method are uniform,and most of them are spherical.When not lyophilized,the average particle size of the microcapsules is between 2.12 and 2.66 mm;the average water content is above 90%.The texture analysis showed that the sodium alginate-chitosan-tea polyphenol microcapsules'hardness,adhesiveness,chewiness,elasticity,recovery and cohesiveness were higher than those of the other three tea polyphenol microcapsules.After lyophilization,the microcapsules are still spherical or elliptical in shape,but their surface morphology changes greatly,the wrinkles,sag collapses or cracks were appeared.The lyophilized microcapsules swelled in aqueous solution for 2h,4h and 6h,showed the swelling ratio was more than 1,and the swelling ratio gradually increased with time,which had a certain capacity of water absorption and expansion.?2?The results were calculated by using Folin phenol colorimetric method,the sodium alginate-chitosan-tea polyphenol microcapsules had the highest embedding rate of 57.76%.Tested by HPLC,both ECG and EGCG were highest in sodium alginate-chitosan-tea polyphenol microcapsules,which were 0.35 mg/g beads and 1.47mg/g beads,respectively.EC and EGC were the highest in sodium alginate-arabin gum-tea polyphenol microcapsules,which were 0.35 mg/g beads and 0.40 mg/g beads,respectively.The results of FTIR experiments showed that hydrogen bond interaction occurs,which proves that tea polyphenols are embedded.?3?The release test of tea polyphenol microcapsules in different carriers?water,stomach,intestinal simulated solution,pH 2 and pH 7.5 aqueous solution?showed that tea polyphenol microcapsules had a certain sustained release effect in different carriers.The residual content of total phenols in the four tea polyphenol microcapsules after released from water,stomach,intestinal simulated solution,pH 2 and pH 7.5 aqueous solution was determined by the Folin phenol method,the results showed that,after the four tea polyphenol microcapsules were released in different carriers,less tea polyphenols remained.However,the amount of tea polyphenols in the sodium alginate-chitosan-tea polyphenol microcapsules was the highest after release in different carriers.HPLC results show that after the four tea polyphenol microcapsules were released in different carriers,the content of each component decreased significantly,and some catechins could not be detected.?4?The retention rate of the unencapsulated tea polyphenol powder during storage period was significantly lower than that of the tea polyphenol microcapsules.The tea polyphenol microcapsules prepared by compounding have higher retention rate and better stability during storage.The water activity of the unencapsulated tea polyphenol powder during storage period was significantly higher than that of tea polyphenol microcapsules.The tea polyphenol microcapsules prepared by the compounding process have a lower water activity increase and a longer storage period during storage.