Preparation Of Non-crystalline Starch And Study On The Structure And Digestibility Of Its Complex With Emulsifier

The complexes formed by starch and emulsifier,considered as type 5 resistant starch,has been widely concerned for its thermostability and resistance to digestion.At present,the complexes are prepared with low starch concentration,leading to the problems of high energy consumption and low yield during the production of complexes,which limits the large-scale industrial production of complexes.Meanwhile,the enhance of starch concentration,accompanied by the increase in viscosity of complex system,is not conducive to the dispersion of amylose and emulsifier and thereby leading to the decrease of complex index and starch resistance to digestion.Therefore,reducing viscosity of complex system is the key to the efficient preparation of complexes.Based on this,dry heat treatment,a sample and safe method,was used to prepared non-crystalline starch.Moreover,the influence of non-crystalline treatment on the formation of starch-emulsifier complexes was studied.On this basis,the preparation system of complex with high concentration was further constructed,which would provide theoretical basis for the industrial production of type 5 resistant starch.Preparation of non-crystalline starch and study on the mechanism of the formation of non-crystalline starch and the reduction of viscosity.Non-crystalline starch was prepared by controlling the dry heat treatment temperature(170,180,190,200 and 210°C)in short time(10 min)using normal maize starch.The mechanism of the formation of non-crystalline starch and the reduction of viscosity were analyzed using light microscope,X-ray diffraction(XRD),attenuated total reflection-Fourier transform infrared spectroscopy(ATR-FTIR),gel chromatography,and rapid viscosity analyzer,et al.The results showed that non-crystalline treatment destroyed the hydrogen bonds,reduced the number of double helices and the ordered accumulation of double helices,which leading the crystalline structure of starch gradually transferred to amorphous state.In addition,the viscosity of starch significantly decreased under the non-crystalline treatment.Compared with native starch,the total non-crystalline starch showed a rapid reduction in the peak viscosity from 3795 to 147 c P.The decrease of viscosity could be ascribed to the change of molecular structure and crystal structure under the non-crystalline treatment.The water holding capacity was weakened as a result from the reduction of long-and short-range ordered structure of starch under non-crystalline treatment,thereby leading to the low viscosity of non-crystalline starch.Meantime,the starch pastes of non-crystalline starch presented low viscosity at ordinary temperature for the reduction of steric resistance and enhancement of fluidity under thermal degradation.Preparation and study of structure and resistance to digestion of complex formed by non-crystalline starch and emulsifier.Glyceryl monostearate(GMS),selected from 5emulsifiers using complex index and resistance to digestion as indicators,was used to prepare complexes with non-crystalline starch to explore the influence of non-crystalline treatment on the complex behavior and resistance to digestion of complex in low viscosity complex system using XRD,ATR-FTIR,differential scanning calorimetry(DSC)and in vitro digestion.The results of soxhlet extraction showed that non-crystalline treatment with relatively low temperature(170 and 180°C)exerted little effect on the complex ability of starch.With the increase of non-crystalline treatment temperature,the complex ability of starch with low viscosity decreased.The content of complexed lipids of the total non-crystalline starch-GMS complex decreased from 1.21 to 0.63g/100 g.XRD and ATR-FTIR analysis found that the long-and short-range ordered structure of the complexes formed in complex system of low viscosity was reduced by non-crystalline treatment.DSC results revealed that compared with NMS-GMS complex,non-crystalline starch-GMS complexes showed a reduction in thermal stability with the decrease of viscosity of the complex system decreases which indicated by the peak gelatinization temperature decreased by 3.92-9.21°C.The results of in vitro digestion showed that the resistance to digestion of starch-GMS complex formed in low viscosity complex system was significantly increased under non-crystalline treatment,and it increased with the increase of treatment temperature.The resistant starch content of total non-crystalline starch-GMS complexes was 8.8% higher than that of NMS-GMS complex,which could be ascribe to the formation of new glucosidic bonds,the enhancement of amylose content and branch density after non-crystalline treatment.Study on the complex behavior,structure and resistance to digestion of complex formed by non-crystalline starch and GMS under high concentration.Starch samples treated with190°C(T-190)was selected to investigate the complex behavior and resistance to digestion of complex under high concentration(38%).The content of complexed lipids in T190-GMS complex increased by 23% compared with NMS-GMS complex measured by soxhlet extraction.The enthalpy value of T190-GMS complex increased from 2.21 J/g(NMS-GMS complex)to 3.77 J/g at high concentration measured by DSC,indicating that more energy was required to destroy the ordered structure in T190-GMS complex.XRD analysis found that the T190-GMS complex exhibited higher degree of long-range ordered structure.In vitro digestion results showed that T190-GMS complex had better resistance to digestion.The hydrolysis rate within 180 min of T190-GMS complex was significantly lower than that of NMS-GMS complex.Besides,the content of rapid digestible starch of T190-GMS complex was 7.0% lower than NMS-GMS complex.In summary,compared with NMS-GMS complex,T190-GMS complex,formed in lower viscosity complex system,exhibited well complex behavior,highly ordered structure and strong resistance to digestion,which is of great significance for the industrial production of the type 5 resistant starch.