Study On Structural And Functional Characteristics Of Taro Starches And Dual Modification Of Taro Starch By Electron Beam Irradiation And Octenylsuccinylation Treatment

In order to explore the structural characteristics,physicochemical and functional properties of taro starches,the correlation among them,and the influence of different beam irradiation dose pretreatment on the properties of octenylsuccinylation taro starch.Fenghua taro,Fenghua seed taro and Wenling taro were selected for this study.The structural characteristics of taro starches were determined by scanning electron microscope,X-ray diffraction,fourier transform infrared spectroscopy and high performance anion exchange chromatography.Swelling power and solubility determination,differential scanning calorimeter,rapid visco analyzer,in vitro digestion and rheometer were used to measure the paraments of physicochemical and functional properties,and then the relationship of among the structural characteristics,physicochemical and functional properties were studied by correlation analysis.Finally,the effect of different beam irradiation dose pretreatment on the structure and properties of octenylsuccinylation taro starch were analyzed by means of the above research methods,so as to provide a basis for the applications and physical modification of taro starches.The main result of this study were as followed:1.The size of taro starch granule was 0.5-2 μm,the shape was irregular,polyhedral and nearly spherical,and the surface of the granule was wrinkled and cracked.The X-ray diffraction patterns of taro starch granule were type A with crystallinity ranged from 26.16%to 28.24%.In the FTIR spectrum,the peak intensity ratios of the 1047cm-1/1022cm-1 were 1.48-1.74,and the granule surface was highly ordered.The average chain length of amylopectin were 19.74-20.14,the contents fa,fb1,fb2,fb3 were respectively 28.09-29.24%,47.69-48.72%,10.50-11.14%,10.48-10.78%.The degree of polymerization(DP)was relatively high at 12.2.The apparent amylose content(AAC)of taro starches were 11.24-20.27%.The peak viscosity(PV)of taro starches were 1599-2991 cP,the trough viscosity(TV)of taro starches were 938.3-1252 cP,the final viscosity(TV)of taro starches were 1542-2819 cP,the breakdown(BD)value were 660.7-1738 cP,and the setback(SB)value were 603.7-1566 cP.Onset temperature(To),Peak temperature(Tp),Conclusion temperature(Tc),Enthalpy of gelatinization(ΔH)and Enthalpy of gelatinization retrogradation(ΔHR)of taro starches were 75.44-76.11℃,80.42-83.74℃,86.63-89.34℃,13.57-19.14 J/g,3.09-5.43 J/g.Rapidly digestible starch(RDS),slowly digestible starch(SDS),resistant starch(RS)content of taro starches were 66.06-71.32%,8.05-16.19%,17.04-20.63%,respectively.The storage modulus(G’)and loss modulus(G")of taro starches at 95℃were 25.9-36.5 Pa,9.5-15.1 Pa respectively.3.Correlation analysis showed that AAC of taro was positively correlated with PV,TV,BD,SB,ΔH,SP,SDS,G’ and G",and negatively correlated with Tp,ΔHR,WSI and RDS.fa was positively correlated with ΔH,G’ and G",but negatively correlated with Tp.fb1 was positively correlated with Tp,but negatively correlated with BD,SP,G’ and G".fb2 was positively correlated with SDS.It showed that the content of amylose and the chain length disribution of amylopectin(especially short amylopectin)were the main factors affecting the physicochemical and functional properties of taro starches.4.Electron beam irradiation significantly influenced the physicochemical and functional properties of octenylsuccinylation taro starch.With the increase of the irradiation dose from 2-50 kGy,the octenylsuccinylation taro starch granule gradually increased in crumbs,the wrinkles and protrusions on the surface continued to deepen,and even the granule ruptured;RDS content and water solubility index continued to increase,but crystallinity,SDS,Tp continued to decline;amylose content and swelling power showed a trend of first increasing and then decreasing,but gelatinization enthalpy,RS,emulsibility and peak intensity of 1047 cm-1/1022 cm-1 in FTIR spectrum showed a trend of first decreasing and then increasing.In actual production,electron beam irradiation pretreatment of dosage of 4 kGy was suitable for the preparation of thickeners and refrigerated and frozen foods.OSTS treated with a dosage of 10 kGy could be used as additives of high-temperature food,hard food and functional nutritional food,as well as adhesives and encapsulants.A dosage of 50 kGy was suitable for the preparation of emulsifiers and high transparency foods.