| Brown rice has various effects due to its rich in active ingredients such as polyphenols.At present,scholars have not fully analyzed the composition,antioxidant and digestion characteristics of polyphenols in colored brown rice,and there is a lack of research on the unified comparison of polyphenols in colored brown rice.In order to further explore the differences in phenolic substances of different colors of brown rice,five colors of brown rice from the same origin in China were collected in this study,the optimal extraction process of brown rice polyphenols was determined,and the differences in the content,composition and antioxidant capacity of the five colors of brown rice polyphenols were analyzed and compared,and the changes of phenolics release and antioxidant activity of five kinds of brown rice during in vitro digestion were discussed.It is expected to provide a theoretical basis for the breeding and processing applications of colored brown rice.The results of this experiment include the following aspects:1.Ultrasonic water enzyme extraction method was used to optimize the optimal extraction process of brown rice polyphenols based on single factor and response surface analysis,the results showed that the material-liquid ratio is 1:30(g / m L),the enzyme addition is 5.5%,the ultrasonic time is 12 min,the ultrasonic power is 340 W,and the ultrasonic temperature is 55?.The total phenol content of the five colors of brown rice is5.318 mg / g for black brown rice,3.892 mg / g for purple brown rice,3.874 mg / g for red brown rice,3.425 mg / g for yellow brown rice,and 3.136 mg / g for green brown rice.2.The composition and content of five colors of brown rice phenolic acids were analyzed and identified by high performance liquid chromatography(HPLC).The retention time of 10 kinds of standard products were determined,and the polyphenol extracts of five kinds of brown rice were tested.The results showed that the composition and content of phenols in different colors of brown rice are different due to different varieties,but the shape of the map is similar.The types of phenolic acids detected in the five kinds of brown rice samples were p-hydroxybenzoic acid,gallic acid,catechins,chlorogenic acid,vanillicacid,caffeic acid,ferulic acid and syringic acid,and the content of gallic acid was significantly higher than that of other phenolic acids,while p-coumaric acid and coumarin were not detected in the five samples.3.The antioxidant capacity of crude extract of brown rice polyphenols were analyzed by 1,1-diphenyl-2-trinitrophenylhydrazine(DPPH),2,2'-biazino-bis-3-ethyl The four evaluation methods of benzothiazoline-6-sulfonic acid(ABTS),superoxide anion free radical scavenging and iron ion reducing power test(FRAP),and taked vitamin C(VC)and water-soluble vitamin E(Trolox)as reference.The results showed that the five kinds of brown rice have good antioxidant activity,and the antioxidant capacity is as follows: black brown rice> purple brown rice> red brown rice> yellow brown rice> green brown rice,however,the antioxidant capacity of the five brown rice polyphenols are still slightly insufficientcompared with Trolox and Vc.4.The in vitro digestion method was used to analyze and compare the changes of total phenol release,phenolic acid composition and antioxidant activity of five kinds of brown rice during in vitro digestion.The results showed that the polyphenol release curves of the five types of brown rice conformed to the exponential equation,the composition and content of phenolic acid and the changes in antioxidant resistance were different in different digestion periods.In addition,the content of phenolic acid and antioxidant activity in the intestinal stage were significantly higher than those in the stomach stage.And the total polyphenol release and the total antioxidant activity are as follows in order:black brown rice> purple brown rice> red brown rice> yellow brown rice> green brown rice. |
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