Study On The Mechanism Of Polyphenols Regulating The Interaction Between Gelatin And Starch

With the improvement of people’s living standards,the demand for functional foods has increased dramatically.Starch is the main component of food,but natural starch has many functional limitations.Gelatin can be used together with starch to strengthen the polymer matrix,and the addition of exogenous active substances such as polyphenols can improve the properties of gelatin-wheat starch complexes.In this study,gelatin and wheat starch were mixed in a certain ratio and a certain amount of polyphenols were added to investigate the effects of polyphenols on the structural properties,physicochemical properties and digestive characteristics of gelatin-wheat starch complexes,and the interaction mechanism of four polyphenols on gelatin-wheat straight chain starch was initially investigated by spectroscopy.The results showed that:Polyphenols and gelatin wheat starch were combined under conduction heating,and different polyphenols had varying degrees of influence on the structure of the composite;The addition of polyphenols reduced the p H,sedimentation rate,water absorption,and swelling power of gelatin wheat starch paste,while increased the transparency and stability after freeze-thaw.The gelatinization and aging of gelatin starch had a certain regulatory effect.Rutin and quercetin increased the elasticity of the composite,while tea polyphenols and quercetin decreased the elasticity of the composite.All four polyphenols reduced the viscosity and rigidity of the gelatin wheat starch paste.Polyphenols weaken the forces between starch molecules and between starch and gelatin molecules,reduced the twining behavior of the double helix structure in starch,and reduced the viscosity of starch in G-WS system in varying degrees.The gelatinization temperature and enthalpy value of the polyphenol group system were lower than those of the G-WS system,indicating that the addition of polyphenols had varying degrees of influence on the structure of starch;Polyphenols could effectively prevent the binding ability of starch and iodine,increase the rupture distance of gel,improve the elasticity,reduced the hardness of gel,and made the texture soft.The molecular chain of wheat starch with polyphenol added in gel was disrupted,the short-range order was reduced,and the difference of DO value of the complex was reduced;The four polyphenols had no effect on the crystallization type of gelatin wheat starch gel,which belonged to typical A-type crystal structure.Added polyphenols can make the organizational structure of the composite system more compact and prevent water loss,with the gallic acid group had the best water retention effect.The addition of polyphenols increases the RS content of gel and improves the digestion resistance.As time goes on,the digestibility of gel without polyphenols is always higher than that of composite gel with polyphenols.The fluorescence burst spectra showed that the four polyphenols affected the fluorescence burst of wheat starch to gelatin to different degrees,but the peak shape of the fluorescence emission peak of gelatin did not change significantly;the addition of the four polyphenols did not affect the type of static burst of wheat starch to gelatin;the value of the number of binding sites(n)of the complexes was calculated by double logarithmic curve analysis,which were all around 2 and had strong binding stability.The binding constants Ka of wheat straight-chain starch to gelatin after the addition of four polyphenols were TP>R>Q>GA,and the binding ability of gallic acid was the weakest;the analysis of thermodynamic parameters showed that the binding force of both without and with the addition of polyphenols(R,TP)was mainly hydrophobic;the binding force of gelatinstraight-chain starch with the addition of polyphenols(Q,GA)was mainly Van der Waals force and hydrogen bonding;according to the FT-IR,the addition of polyphenols changed the intensity and position of the absorption peaks in the infrared spectrum of gelatin-wheat straight-chain starch,probably the polyphenols changed the functional group structure of gelatin resulted in the gelatin conformation was changed.According to the single-factor experimental results and response surface design analysis,the optimal process of gelatin-wheat starch film was obtained as follows: gelatin concentration 14%,starch addition 76%,glycerol addition 36%,and the tensile strength of the film was 23.50 MPa;the physical properties of the composite film were tested and the tensile strength of the composite film increased to different degrees after the addition of four polyphenols;compared with the G-WS film,except for the elongation at break of Q-G-WS films increased,the elongation at break of other films decreased;due to the color of polyphenols,the effect on the light transmittance and color of composite film was different;the addition of polyphenols reduced the water content and water solubility of composite film and increased water resistance;the addition of polyphenols could effectively reduce the water vapor transmission rate and oxygen transmission rate of composite film.Through the test of antibacterial properties of composite film.it was found that the inhibition effect of the same polyphenol on Gram-negative bacteria was more obvious than that of Gram-positive bacteria;meanwhile,the biodegradation rate of the composite film with the addition of polyphenol was higher than that of the gelatin-wheat starch film;compared with the four polyphenol groups,the gallic acid group had the best antibacterial effect;And after adding polyphenols,the plane of the film becomes more uniform and the cross section pattern becomes clearer.