| Diets rich in starch are an important contributor to obesity and diabetes.Polyphenols can inhibit the digestion of starch by interacting with enzymes or starch.This will increase the amount of resistant starch(RS)and slowly digestible starch.RS has a positive prebiotic effect.Thus,polyphenols become an ideal option for dietary intervention in starch digestion.The mechanisms of polyphenols inhibiting starch digestibility through different pathways under daily dietary conditions are not well studied.In addition,studies on the probiotic effects of RS resulting from the interaction of polyphenols with starch have rarely been reported.This study aimed to simulate the dietary intake of polyphenolic foods in the daily diet using cinnamic acidbased phenolic acid,which was found in high concentrations in grains,as the object.The dietary intake of polyphenolic foods in the daily diet was simulated.This study systematically investigated the mechanisms of interaction and conformational relationships of how cinnamic acid-based phenolic acids inhibited starch digestion in different ways.The relationship between the digestibility of the complex formed by phenolic acids and starch after retrogradation and multi-scale structural change was also intensively investigated.Finally,the probiotic effect of RS produced by the digestion of caffeic acid(CA)in complex formation with common corn starch(CS)was investigated.This will provide a further theoretical basis for the study of phenolic acids application in the regulation of starch digestion.First,cinnamic acid(CIA),CA,ferulic acid(FA)and 3,4-dimethoxy cinnamic acid(3,4-m CIA),and CS were selected as materials.Physical mixing and co-gelatinization treatments were employed to simulate the two main dietary intake modes of phenolic acids.The mechanism of phenolic acids’ effect on digestive inhibition was investigated under both treatments.It was found that phenolic acids inhibited the digestibility of CS under both treatments.Rapidly digestible starch(RDS)content was reduced and RS content was significantly increased.The co-gelatinization treatment improved the inhibitory effect of phenolic acids on CS digestibility.In particular,the RS content was elevated by 8.36% after cogelatinization of CS with 10% CA compared to the physically mixed treatment.The inhibitory effect of phenolic acids on CS digestibility followed the order: CA > FA > 3,4-m CIA > CIA.Under the physically mixed condition,phenolic acids inhibited the activity of α-amylase and α-amyloglucosidase(AMG)mainly by binding to them,which ultimately led to a decrease in the digestibility of CS.Phenolic acids were more effective in inhibiting α-amylase activity.The binding of phenolic acid with α-amylase was mainly driven by van der Waals forces,hydrogen bonding,π-π stacking,and salt-bridge interactions.The binding of phenolic acids to AMG was driven by van der Waals forces,salt bridge interactions,and hydrogen bonding interactions.The binding of phenolic acids to AMG was difficult and unstable due to the narrow binding pocket of AMG.The hydroxyl and methoxy groups on the benzene ring act to stabilize the binding of phenolic acids to both enzymes.The hydroxyl group was more effective in promoting the binding of the two.Phenolic acids co-gelatinization with CS increased the solubility and swelling power of CS.Phenolic acids decreased the peak temperature(PT),peak viscosity(PV),and final viscosity(FV)of CS and increased the setback value.10%CA had the most significant effect on CS gelatinization,which decreased PV value by 97 c P,FV value and PT value by 964 c P and 3.4℃,respectively.Rheological analysis showed that may form a small amount of temporary entanglement zone with starch,which led to a special structural domain that resists digestion.In addition,the co-gelatinization treatment had a retarding effect on phenolic acids,which prolonged the contact time between phenolic acids and enzymes.In conclusion,the co-gelatinization of phenolic acids with CS improved the resistance of starch.In particular,the difference in structure was the key factor for the inhibition of starch digestion by phenolic acids.Then,based on co-gelatinization,the interaction mechanism between cinnamic acid-based phenolic acids and CS and their conformational relationships were further investigated.The mechanism of the interaction on the inhibition of starch digestibility by phenolic acids was thoroughly investigated.The results of the quartz crystal microbalance showed that phenolic acids interacted with CS.CA was bound to CS in the highest amount,followed by FA,CIA,and 3,4-m CIA in descending order.The phenolic acids bound to CS in the order of strength:CA > FA > 3,4-m CIA > CIA,which was consistent with the inhibition of digestibility.The results of X-ray diffraction and isothermal titration calorimetry experiments indicated that phenolic acids formed weakly bound complexes with CS.The lowest digestibility was observed for the complex formed by the hydrogen bonding of CA with CS.This indicates that the hydroxyl group on the benzene ring of phenolic acids played a key role in the anti-digestion by forming complexes.In contrast,the interaction of FA,3,4-m CIA,and CIA with CS was mainly driven by hydrophobic interactions.The type of interaction between phenolic acids and CS depends on the functional group on the benzene ring of the phenolic acids.The two hydroxyl groups on the benzene ring could induce hydrogen bonding between phenolic acids and CS.The presence of methoxy transforms the interaction of phenolic acids with CS toward hydrophobic interaction.The results of iodine binding experiments showed that phenolic acids mainly interacted with the amylose of CS.The crystallinity of the complexes formed by phenolic acids and CS was not significantly different from that of CS,but the short-range orderliness of the complexes was decreased compared to that of CS.In conclusion,the interaction of phenolic acids with CS under co-gelatinization treatment was responsible for its significantly higher RS content than the physical mixing treatment.The inhibitory effect of phenolic acids on digestibility was influenced by a combination of the amount,type,and intensity of the interaction.To investigate the change of the formed complexes after the co-gelatinization during the storage,the samples were stored for 14 d.The interaction between CS and phenolic acids was analyzed for the pattern of influence on its digestibility and multiscale structure after retrogradation.The results showed that the interaction between phenolic acids and CS inhibited CS retrogradation and reduced the increase in RS content due to retrogradation.The inhibition effect followed the order of CA > FA > CIA > 3,4-m CIA,which was consistent with the order of the binding amount of phenolic acid.Under the co-gelatinization treatment,CIA,CA,and FA were able to improve the increase of CS hardness and decrease of cohesion caused by retrogradation.The hardness of CS gels increased due to the low binding of 3,4-m CIA to CS and the unbound phenolic acids filling in the gel network structure.The interaction of CS with phenolic acids limited the resolution of water during its retrogradation.CA showed the best inhibition of water resolution.CA showed the best inhibitory effect on water resolution,then followed by CIA,FA,and 3,4-m CIA.The inhibitory effects of CIA,FA,and 3,4-m CIA on water resolution are negatively correlated with the hydrophobicity of their structures.The cogelatinization of phenolic acid and CS decreased the ΔH of CS.This hindered the reorganization of short-range ordered structures and crystalline structures during the CS retrogradation regeneration process.The interaction between phenolic acids and CS mainly affected the retrogradation of the background region of amylose,forming a thin and loose lamellar structure that was easily digestible.In summary,under co-gelatinization treatment,phenolic acids interact with CS,which can effectively inhibit the regeneration of CS.The inhibition effect was positively correlated with the phenolic acids’ amount binding to CS.The interaction affected the regeneration of short-range,long-range,and lamellar structures of CS during retrogradation,and the formed complex structures were more digestible.Finally,the weakly bound complex generated by the co-gelatinization of CA and CS was studied in comparison with V-type complexes prepared by the high-pressure homogenization method.The probiotic effect of complex-based RS was investigated.Weakly bound complexbased RS exhibited for B-type crystal structures.V-type complex-based RS exhibited for B +V type crystal structures The in vitro fermentation results showed that the complex-based RS was able to increase the amount of acetic acid,propionic acid,butyric acid,and total shortchain fatty acids while facilitating distal colonic fermentation.Compared with V-type complexbased RS,weakly bound complex-based RS can significantly increase the production of propionic acid.V-type complex-based RS was able to significantly increase the content of butyric acid and acetic acid.Both complex-based RSs were able to increase the abundance of gut microbiota and had a role in modulating the gut microbial structure after in vitro fermentation.There were significant differences in the effects of the two complex-based RSs on the abundance of certain bacterial genera.The effect of weakly bound complex-based RSs on the abundance of the genera torques-Ruminococcaceae and Bifidobacterium was significantly higher than that of V-type complex-based.The effect of CH-CA-HG on the abundance of Prevotella,Roseburia,and Lachnospiraceae was more significant.This suggested that the probiotic effects of the complex-based RSs might depend on the structural differences caused by their binding types.The results indicated that CA-CS complex-based RSs had good probiotic effects.Moreover,their effectiveness was related to the structure of the RS and the degree of complexation. |
PDF Full Text Request