| Bound phenol as a plant component with multiple biological activities,it can react with starch and affect the sensory quality and nutritional value of starch foods.In this paper,three methods of alkaline hydrolysis,acid hydrolysis,and enzymatic hydrolysis were used to extract purple sweet potato bound phenol.The extraction rate and antioxidant activity were measured.It was identified by LC-MS/MS,and the suitable extraction method and composition of purple sweet potato bound phenol were studied.Based on this,with the aid of rapid vscosity analyzer,texture analyzer,rheometer,scanning calorimeter and other instruments,the gelatinization properties,texture properties,rheological properties and thermodynamic properties of purple potato starch combined with bound phenol were studied.By measuring the inhibition rate of α-amylase and glucosidase activity by bound phenols and the changes in RDS,SDS,and RS contents during in vitro simulated digestion experiments of starch,the effect of the bound phenol addition on the digestibility of purple potato starch was studied.On this basis,X-ray diffractometer and Fourier infrared spectroscopy were used to determine the structure of purple potato starch before and after compounding,and to explore the combination of the two,to provide some theoretical guidance for the industrial application of purple potato starch.Provide a theoretical basis for the development of related functional foods,and provide a theoretical basis for the modification of starch products.The main findings are as follows:1.From the results of the extraction yield,composition and antioxidant activity of purple potato bound phenol,it was concluded that the most suitable extraction method for purple potato bound phenol is alkaline hydrolysis,4-hydroxybenzoic acid,ferulic acid,isoferulic acid,and caffeic acid.It is the main bound phenol of purple sweet potato.Among them,the extraction rate of the alkaline hydrolysis of bound phenol was the highest under the three extraction methods,which was 0.19 g/100 g.From the antioxidant activity results of purple sweet potato bound phenol extract,it was concluded that the scavenging ability of the boundphenol extract to the four free radicals in the three hydrolysis modes is in the order of strong to weak: ABTS> DPPH> OH> superoxide anion;among them,the bound phenol extract obtained under alkaline hydrolysis conditions has the strongest scavenging ability to four free radicals,reaching 63.66%,63.16%,57.43%,56.30%.The LC-MS/MS method was used to identify the bound phenolic extracts of purple sweet potato.The three types of hydrolysis were the most types of phenols obtained by alkaline hydrolysis,including 4-hydroxybenzoic acid,ferulic acid,and isoferulic acid.The bound phenols obtained by acid and enzymatic hydrolysis are 4-hydroxybenzoic acid,caffeic acid and 4-hydroxybenzoic acid.2.Four kinds of bound phenols(4-hydroxybenzoic acid,ferulic acid,isoferulic acid,and caffeic acid)combined with purple potato starch changed the gelatinization,aging,and gel properties of purple potato starch.Among them,by increasing the enthalpy of gelatinization,reducing the thermal stability of starch paste,reducing the solubility and swelling power of starch,improving the stability of cold starch paste,thereby delaying the aging of starch,4-hydroxybenzoic acid have the most significant effect on it;by reducing the viscoelasticity,hardness,cohesiveness and elasticity of the purple potato starch gel,the network structure of the starch gel system is weakened,4-hydroxybenzoic acid have the most significant effect on it;by shortening the settling time of purple potato starch,it promotes the settling of purple potato starch,with the most significant effect on 4-hydroxybenzoic acid;by improving the water release of purple potato starch paste after freezing and thawing Rate,reducing the freeze-thaw stability of purple potato starch paste,with the most significant effect on4-hydroxybenzoic acid,thereby preventing the loss of water during the long-term aging process of purple potato starch and reducing the shrinkage of the structure.3.Four types of bound phenols(4-hydroxybenzoic acid,ferulic acid,isoferulic acid,and caffeic acid)combined with purple potato starch reduced the RDS content of purple potato starch during simulated in vitro digestion and increased RS content,Among them,4-hydroxybenzoic acid has the most significant effect on RDS,and 4-hydroxybenzoic acid and ferulic acid have the most significant effects on RS content.Compared with non-added bound phenol starch,they have increased by 27.20% and 25.35%,respectively.The results ofthe measurement of the inhibition of α-amylase and glucosidase by four kinds of bound phenols showed that the inhibition rate gradually increased with the increase of concentration,and there was a significant difference.The inhibitory rates of glucosidase and glucosidase were the highest,with IC50 of 0.109 and 0.114 mg/m L,respectively.4.Four kinds of bound phenols(4-hydroxybenzoic acid,ferulic acid,isoferulic acid,and caffeic acid)combined with purple potato starch significantly reduced the p H value of purple potato starch solution and its ability to bind iodine,among which the most significant effect is4-hydroxybenzoic acid.The results of Fourier transform infrared spectrometry showed that there were no new peaks in the spectra of the four types of purple sweet potato bound phenol after interacting with purple sweet potato starch.The two are bound by non-covalent bonds.The X-ray diffraction measurement results show that the hydroxyl groups of the four kinds of bound phenol formed hydrogen bonds with the hydroxyl groups of their starch,which inhibited the recrystallization of starch and the aging of purple potato starch. |
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