Interaction Between Polyphenol And Corn Starch And Its Effects On Digestibility And Processing Properties Of Starch

Many functional materials are added into starchy food in order to improve the functional properties or specifically change the properties of starchy food.And polyphenol is one of this kind of materials.In addition,the destruction of cells or tissues is often involved during food production.It results in the release of endogenous substances and cellular exogenous substances and the contact between endogenous polyphenol and starch,which influences the properties and function of starchy food.Therefore,the research on the effects of interaction between starch and polyphenols on properties of starch has a guiding significance for the development of new nutritional starchy products and industrial production of polyphenols and starch systems.This paper reviews the rules of interaction between polyphenols and starch and analyses the effects of interaction on digestibility and processing characters of starchy food.The polyphenol with different structures?caffeic acid,quercetin and?-?-epigallocatechin gallate?EGCG??and the corn starch with different contents of amylose?waxy starch,normal corn starch and high amylose starch?were chosen as materials.Meanwhile,co-cooking,which is the most common processing procedure of starchy food,was chosen to prepare the complex of starch and polyphenols.Firstly,the interaction between polyphenols and starch was investigated.Thermo-gravimetric analysis?TGA?results showed that the complex of corn starch with caffeic acid,quercetin and EGCG decreased the pyrolysis temperature of corn starch control from 317.8?to 316.5?,312?and 310.8?,respectively.And the pyrolysis peak of polyphenols in complex missed or decreased compared with polyphenols control and the proportion of mass loss of caffeic acid?10%?interacted with waxy starch,normal corn starch and high amylose starch reduced to 4.50%,3.91%and 2.75%,respectively.The results prove the interaction between starch and polyphenol and illustrate that more hydrogen bonds,lager cross-section size of polyphenols and higher amylose content helps to improve the strength of complex combination.The absorbance values of complex of starch and iodine decreased with the increasing of the addition of polyphenol.The degree of reduction was more obvious with the increasing of content and molecular size of polyphenol.Nuclear magnetic resonance?NMR?results suggested the chemical shift values for H and C of polyphenols in complex were shifted upfield.The C signals of caffeic acid,quercetin and EGCG in complex had a upfield shift with 0.15⁰.16 ppm,0.47⁰.48 ppm and 0.48⁰.50 ppm.It illustrated hydrogen bonds were formed between starch and polyphenols.And the strength of interaction was increased with the increasing content of polyphenolic hydroxyl groups and molecular size.Secondly,the effects of interaction between polyphenols and starch on digestibility were investigated.In vitro digestion showed polyphenols inhibited the mixed enzyme of vitro digestion system according to Englyst method.The inhibition strengthen as the increasing content of polyphenols.10%?based on starch weight?of caffeic acid,quercetin and EGCG co-cooked with corn starch decreased the proportion of rapidly digestible starch?RDS?from73.9%to 70.3%,69.2%and 63.2%,respectively.Furthermore,10%?based on starch weight?of caffeic acid,quercetin and EGCG mixed with enzyme and added into the cooked starch,which decreased percent of RDS from 73.9%to 70.2%,61.8%and 69.4%,respectively.The effect of interaction between polyphenols and starch on digestion was investigated by comparing the digesition of co-cooked samples and non-co-cooked ones.The effects of interaction strengthen with the increasing content of soluble polyphenols,cross-section size and hydroxyl groups of polyphenols and content of amylose.By enzyme kinetic analysis,the inhibition of pancreatic alpha-amylase by polyphenols is non-competitive.Thirdly,the effects of interaction between polyphenols and starch on processing characters were investigated.The solubility and swelling power showed that polyphenols could increase the solubility and swelling power of corn starch as the concentration increased.The pasting properties were investigated by rapid viscosity analysis?RVA?.RVA results illustrated that the polyphenols declined the peak viscosity,gelatinization temperature and final viscosity and stability at high temperature and inhibited the retrogradation as the concentration increased.Differential scanning calorimeter?DSC?results suggested quercetin and EGCG reduced the enthalpy of starch gelatinization from 11.64 J/g to 9.41 J/g and 8.96J/g,respectively.Caffeic acid had little influence on that of corn starch but it decreased that of waxy starch from 13.93 J/g to 8.71 J/g,which illustrated amylose weaken the influence of caffeic acid on enthalpy of starch.What's more the temperature of starch gelatinization decreased as the addition of EGCG and caffeic acid,while that increased as the addition of quercetin.Rheology test showed polyphenol decreased the G'and G”of the system and the influence on solid properties of system were greater.Fourier-transform infrared?FT-IR?spectroscopy measurement showed the ratio of absorbance at 1047/1022cm^-1 decreased by low addition of polyphenols,but increased by high addition of polyphenols.It illustrates low concentration of polyphenol decrease the ordered degree and high concentration of polyphenol increase that.