Study On Antioxidant Activity Of Blackberry Phenolic Compounds And In Vitro Simulated Digestion

Blackberries are high in phenolics and contain higher levels than other fruits and vegetables such as blueberries,strawberries,red grapes and apples.However,the composition and content of phytochemicals vary greatly among blackberry varieties.And in the process of digestion,the change trend of blackberry polyphenols and flavonoids content and antioxidant activity is not clear.Therefore,it is very important to select high quality varieties to study the variation of phenolic species in vitro during simulated digestion.In this paper,three experiments were carried out with different blackberry varieties were used as raw materials to compare the differences in phenolic content and antioxidant activity.After screening out better varieties,the changes of phytochemicals composition,total phenols,total flavonoids and antioxidant activities after simulated digestion in vitro were preliminarily studied.The main contents and results are as follows:(1)This article analyzed and compared the phytochemicals of the free and bound fraction of eight blackberry varieties.A total of fifteen phenolic compounds were found in blackberry(three anthocyanins,four flavonols,three phenolic acids,two proanthocyanidins and three ellagitannins).Ten phytochemicals were identified in the free fraction and five in the bound fraction.The contents of total phenolics and total flavonoids were detected by Folin-Ciocalteu colorimetric method and borohydride/chloranil protocol.Free phenolics are the main phytochemicals in blackberry.The differences of antioxidant activity between different varieties were investigated,and it was found that the antioxidant activity of the free fraction was higher than that of the bound fraction.Boosted Regression Trees analysis found significant correlations between antioxidant activity and phenolic profile,and showed that cyanidin-3-O-glucoside and chlorogenic acid appeared to be the most relevant to explain antioxidant activities of free fractions,while ferulic acid appeared to be the most relevant to explain antioxidant activities of bound fractions.Principal component analysis showed that Kiowa was the best variety among the eight varieties due to itsphytochemical profile and antioxidant activity.This study provides a theoretical basis for better selection and retention of high-quality varieties,and a scientific basis for the development of functional products.(2)In this paper,the changes of phenolic substances in three samples of blackberry free phenolics,whole berry and berry residue during simulated digestion in vitro were studied.High performance liquid chromatography(HPLC)and mass spectrometry(ms)were used for qualitative and quantitative analysis of phytochemicals in blackberry simulated digestion in vitro.Eighteen phytochemicals(2 anthocyanins,7 flavonols,6 phenolic acids,1 procyanidins and 2 ellagic tannins)were identified,and three new substances were found due to digestion and catabolism.Folin-Ciocalteu colorimetric method and borohydride/chloranil protocol were used to analyze the changes of total phenolics and total flavonoid during in vitro digestion simulation.The content of total phenolics and total flavonoid of the three samples in this stage did not change significantly in the oral cavity.After the strong acidity of the gastric environment,the total phenolics and total flavonoid have a small part of the increase.In the stage of small intestine,the free phenolics samples produced a new substance,protocatechuic acid.A new substance isorhamnetin xyloside was produced from the whole berry sample of blackberry.The contents of total phenolics and total flavonoid of the three samples increased in different degrees in the small intestine.In the colon stage,although free phenolics and whole berry samples produced a new substance coumaric acid,most of the phenolic acids and flavonoid in the three samples were greatly reduced.All in all,during digestion,the phenolics in the blackberry were gradually absorbed by the human body through the oral cavity,stomach and small intestine,and flavonoids were gradually absorbed by the human body through the small intestine and colon.After digestion,the polyphenols and flavonoids in the blackberry were significantly reduced(3)In this paper,the antioxidant activities of free phenolics,whole fruit and fruit residue of blackberry were studied during simulated digestion in vitro.In oral stage,the antioxidant activity of free phenolics and whole blackberry samples decreasedslightly,while the antioxidant activity of berry residue samples did not change significantly.In oral stage,the antioxidant activity of free phenolics and whole berry fruit samples decreased slightly,while the antioxidant activity of berry residue samples did not change significantly.In gastric stage,the antioxidant activity of free phenolics increased slightly,while the antioxidant activity of whole berry and berry residue samples decreased by 12%.The antioxidant activity of free phenolics and whole berry samples after gastric digestion was lower than that of the original samples.In the small intestine stage,the antioxidant activity of berry residue was stronger than that of free phenolics and whole berry,but the antioxidant activity of berry residue and free phenolics decreased significantly,while the antioxidant activity of whole berry increased.In the colon stage,the antioxidant activities of the three samples all showed a decreasing trend.The results showed that the antioxidant activity of free phenolics samples decreased gradually with digestion,and the antioxidant activity of whole fruit and fruit residue samples was gradually released from the small intestine and colon and gradually absorbed by the human body.On the whole,the antioxidant activity of blackberry was significantly reduced after digestion...