Study On In Vitro Digestion Simulation Of Aronia Melanocarpa And Properties And Application Of Its Proanthocyanidins

Chokeberry（Aronia melanocarpa）berry is an edible fruit rich in phenols.It has been proved that chokeberry has high polyphenol content and strong antioxidant activity in berries.However,there are few studies about the changes of active substances after gastrointestinal digestion and the functional properties as well as applications of proanthocyanidins.This thesis preliminarily studied the changes of phenols and antioxidant activities in chokeberry subjected to in vitro digestion,and used high performance liquid chromatography（HPLC）to detected the changes in the content of monomeric phenol.Subsequently,the proanthocyanidins that have been preserved the most after gastrointestinal digestion were selected for optimization of the extraction process and research on its antioxidant activity,hypoglycemic activity and stability.Finally,proanthocyanidins were microencapsulated.These experimental results provide a scientific basis for the development and application of natural products of chokeberry.The main findings are as follows:（1）Through in vitro digestion,the changes of polyphenols,flavonoids contents and antioxidant activity in chokeberry were studied,and the contents of phenolic compounds in four fruits（chokeberry,blueberry,mulberry,Vitis amurensis）after digestion were compared.Then monomeric phenols were detected by HPLC.The results showed that the contents of polyphenols and flavonoids in chokeberry increased significantly after digestion,while DPPH and ABTS⁺·radical scavenging capacity decreased by 36.84%and 8.55%respectively after intestinal digestion.Compared with mulberry,blueberry and mountain grapes,chokeberry has the greatest advantages in terms of the original polyphenol and flavonoid contents as well as the retention after digestion.In addition,HPLC detected that chlorogenic acid as well as quercetin were completely degraded,the content of procyanidin B₂was reduced while epicatechin content was increased,and the content of hyperoside was not significantly changed after digestion.It can be seen that the proanthocyanidins were the most abundant monomeric phenols after digestion,which made chokeberry retain certain antioxidant activity after digestion.（2）The response surface optimization method was used to optimize the hot alcohol extraction process of proanthocyanidins in chokeberry.Under the optimal extraction conditions（liquid-to-material ratio of 36:1,ethanol concentration of 40%,extraction temperature of 81℃and extraction time of 177 min）,the yield of proanthocyanidins from chokeberry was 24.33%,which was only 0.034%less than the theoretical prediction.In addition,DM130 macroporous resin was used to separate and purify proanthocyanidins,and the purity reached 94.70%,which was 52.84%higher than the crude extract.（3）This study examined the in vitro antioxidant as well as hypoglycemic activities of proanthocyanidins from chokeberry,and the effects of different environmental factors on the stability of proanthocyanidins.In vitro antioxidant experiments found that proanthocyanidins of chokeberry had strong antioxidant capacity,manifested in DPPH,ABTS⁺·free radical scavenging ability and total reducing power.Among them,IC₅₀for DPPH and ABTS⁺·radicals were 39.19 and 20.32μg/m L,respectively;The results of hypoglycemic activity experiments showed that proanthocyanidins of chokeberry can effectively inhibitα-glucosidase(IC₅₀was 1.22μg/m L);Stability experiments showed that the processing and storage of proanthocyanidins should be kept in a low temperature and dark environment without contact with iron and copper containers.And at the same time,the use of strong base and weak acid salt additives such as sodium benzoate and potassium sorbate should be reduced;During in vitro digestion,proanthocyanidins content increased significantly after oral-gastric digestion and significantly decreased after intestinal digestion.（4）Using gelatin and pectin as wall materials,the proanthocyanidins microcapsules of chokeberry were prepared by composite coagulation method.The response surface optimization method was used to optimize the process parameters of the microcapsule wall material.Under the optimal process conditions（wall material concentration 1.54%,wall material mass ratio 1:2.25,p H 3.2）,the aggregation rate was 63.01%,which is theoretically predicted The difference is only 0.91%.Based on the wall material technology,the optimal conditions of the proanthocyanidins microcapsules were obtained through a single factor test based on the embedding rate.Finally,the best values of each process parameter of the proanthocyanidins microcapsules of chokeberry were obtained:the wall material concentration was 1.54%,the wall material mass ratio was 1:2.25,the p H was 3.2,the core/wall mass ratio was 1:2,TG The amount of enzyme added was 30%（w/w gelatin）,and the curing temperature was 15℃.Under this process conditions,the embedding rate of proanthocyanidins in chokeberry can reach 87.30%.Through in vitro digestive simulation,it was found that the microcapsules played a slow release effect on proanthocyanidins,and it could reduce their loss in the process of intestinal digestion.