Study On Structures And Properties Of Potato Resistant Starch Prepared With Different Methods

RS3(Resistant Starch ?)has good processing performance and physiological characteristics,which is widely used in food processing.There are many studies on improvement of the prepared methods of RS3 in recent years.However,there are few reports on the effects of the structures and properties of resistant starch caused by different prepared methods.Potato resistant starches are prepared by microwave dual-enzymatic treatment,heat-moisture enzymatic treatment,microwave heat-moisture treatment and dual autoclaving-retrogradation treatment in this study.The aggregate state structure and chain structure of resistant starch are analyzed,and the differences of properties for resistant starch are investigated.On the basis of these studies of resistant starches prepared with different methods,relationship between structures and properties are concluded by correlation analysis.The results are as follows:(1)Effects of prepared methods on the aggregate state structure and chain structure of resistant starch are studied.The granule morphology of resistant starch is destroyed,which the surface is rough and obvious layered fluctuations are found.The shape of resistant starches is similar as irregular gravels,which diameter is about 8-30?m.The resistant starches prepared with microwave dual-enzymatic treatment,heat-moisture enzymatic treatment and dual autoclaving-retrogradation treatment can observe significant holes and recesses of the honeycomb structure.The birefringence patterns of resistant starches have all disappeared.They are C-type crystal structures,and the degree of crystallinities are increased compared to the original starch.Fourier transform infrared spectroscopy shows that functional groups of starch and resistant starches are similar,but their ratio of intensity(R1047/1022)is increased.The weight-average molecular weight(Mw)of resistant starches prepared with microwave dual-enzymatic treatment is higher than that of potato starch,and its molecular weight distribution was relatively uniform.But the weight-average molecular weight(Mw)of resistant starches prepared with the other three treatments is lower than that of the original starch,and their distribution of the molecular weight of the other three resistant starches is not uniform.(2)Effects of prepared methods on properties of resistant starches are studied.The yields of resistant starch are significantly higher than that of the original starch.During the range of 50?90 0C,solubilities of resistant starches prepared with dual autoclaving-retrogradation treatment are superior to those of the other three resistant starches,in which microwave dual-enzymatic treatment has the worst solubility.While the swelling power shows the opposite result.UV-visible absorption spectroscopy confirms that the resistant starches are a complex of amylose and amylopectin.The peak viscosity,trough viscosity,final viscosity and breakdown of resistant starches prepared with microwave dual-enzymatic treatment and heat-moisture enzymatic treatment are all higher than those of original starch.The resistant starches are non-Newtonian fluids.Resistant starches of microwave heat-moisture treatment and dual autoclaving-retrogradation treatment show shear-thinning behavior,but resistant starches prepared with microwave dual-enzymatic treatment and heat-moisture enzymatic treatment are shear thickening fluids.The oscillatory experiments show resistant starches are weak gel behavior and all of them exhibited elastic behavior.The To,Tp,and Tc of resistant starches are higher than those of potato starch.The enthalpy value of resistant starches prepared with microwave dual-enzymatic treatment and heat-moisture enzymatic treatment are increased,while resistant starches prepared with microwave heat-moisture treatment and dual autoclaving-retrogradation treatment are decreased.(3)Correlation analysis of structures and properties of resistant starch are studied.Structural parameters of crystallinity,ordering degree and molecular weight of resistant starches have significant effects on physical properties,gelatinization properties,rheological properties and thermal properties.The higher crystallinity,molecular weight and ordering degree of resistant starches,the better of the yield and swelling power.And the fluid properties of resistant starches increase consistency index and deformation ability.During the gelatinization of resistant starches,the viscosity,breakdown and setback are increasing,but it is not easy to be gelatinized.