Interaction Between Tea Polyphenols And Meat Protein And Its Effect On Digestion And Absorption Properties

Tea polyphenols?TP?are the general name of the polyhydrophenols and their derivatives in tea,among which EGCG,ECG,EGC,EC etc are the main active components of TP,which have many biological activities,such as scavenging free radicals and antioxidant activity,antitumor,improving cardiovascular function and so on.However,TP is rich in active hydroxyl,it is easy to oxidize polymerization or degradation resulting in a decline in biological activity.It has been reported that proteins and polyphenols can interact with each other and increase their activity,but the current research still focuses on the interaction between a single tea polyphenol monomer and a single protein molecule,and the praise and criticism are mixed.Based on this,the interaction between TP and chicken protein?CP?,fish protein?FP?,beef protein?BP?was investigated in the present study,and the effect of TP binding with protein on the digestion,absorption and the antioxidant activity was also studied to try to reveal the interaction mechanism between TP and meat protein,which may provide theoretical guidance and reference for reasonable dietary intake.The main research contents and results are as follows:1.Study on the interaction and mechanism between tea polyphenols and meat proteinThe interaction between TP and three kinds of meat protein and its mechanism was studied by means of spectral and circular dichroism combined with mathematical analysis,and the antioxidant activity of the compounds was evaluated by free radical scavenging activity in vitro.The results showed that the combination of TP monomers with CP,FP and BP could induce fluorescence quenching of the three proteins,and the process was static quenching.The combination of EGCG with BP,ECG with CP,FP and BP,EGC and FP mainly depended on hydrogen bond and van der Waals force.The combination of EGCG and CP mainly depends on electrostatic force.The combination of EGC and CP,EGCG and FP,EGC and BP mainly depends on the hydrophobic force.The combination of tea polyphenols monomer and three kinds of proteins can cause the changes of the conformation units of the secondary structure of the protein.When different proteins were combined with the same tea polyphenolic monomer?EGCG/ECG/EGC?,?-helix??-sheet??-turn and random coil contents changed differently.In a certain concentration range,the combination of tea polyphenols with three proteins can improve the DPPH·and ABTS+·scavenging ability of tea polyphenols.2.Effects of tea polyphenols on the digestibility after binding with meat proteinIn vitro simulated digestion and high performance liquid chromatography?HPLC?were used to study the effects of TP on gastrointestinal digestion and antioxidant activity of three meat proteins.After adding three proteins to the TP solution before simulated digestion,the contents of EGCG,ECG and EGC decreased significantly.After oral simulation digestion,the polyphenols content in the four groups decreased slightly.After simulated digestion,the phenolic compounds in the TP-protein complex were released,and the changes of the three kinds of polyphenols were different.After intestinal digestion,the contents of EGCG,ECG and EGC in TP decreased.The antioxidant capacity of the TP-protein complex was enhanced during the digestion phase,and the scavenging capacity of DPPH·and ABTS⁺·at the end of digestion was higher than that of TP alone.3.Effects of tea polyphenols on the absorption characteristics of meat proteinUsing Caco-2 cell model,the effects of TP and three meat proteins on the absorption characteristics of intestinal digestible juices were studied.At different absorption time points,the ECG cumulative transfer volume of TP digestion solution and TP-meat protein complex digestion solution was in order of TP digestion solution?TP-CP?TP-BP?TP-FP digestible solution.At 120 min,the P_app values of ECG in TP,TP-CP,TP-FP and TP-BP digestive juices were 4.91×10-7,3.73×10-7,3.25×10-7,and 2.93×10-7,respectively,all of which were not easily absorbed by the human body.However,compared with TP-FP and TP-BP,TP-CP and TP were easier to penetrate through Caco-2 cells.