Study On Structure,Physicochemical Properties And Stable Emulsion Of Modified Lily Starch

Natural starches such as lily starch were widely used as thickeners,gelling agents,colloid stabilizers and fillers.However,due to the disadvantages of easy aging,easy gelatinization,low solubility in cold water,poor heat resistance,poor shear force,mechanical resistance and poor structural change,starch has limited its application in food and other industries.Therefore,a variety of physical,chemical and biological methods were used to alter the structure of starch particles for thr unique properties.To investigate the effects of ultra-high pressure and octenyl succinic anhydride on the structure and properties of lily starch.In this paper,the structure and properties of lily starch treated by ultra-high pressure and octenyl succinic anhydride were studied,and the modified starch stabilized emulsion was used to provide reference for the research and application of lily starch.1.In this study,starch extracted from lily bulbs were modified using an ultra-high pressure（UHP）treatment at six different pressure levels（100,200,300,400,500,and600 MPa）.The effects of UHP treatment on the physicochemical and morphological properties of lily starch were investigated.The morphological observation revealed that UHP treatment led to particle expansion and aggregation.Compared with the native and lily starch treated at 100 500 MPa,the lily starch treated at 600 MPa exhibited almost completely disrupted morphology and a larger particle size,indicating nearly complete gelatinization of the starch.The relative crystallinity of the UHPtreated starch remarkably reduced.Gelatinization temperatures via differential scanning calorimetry decreased with increasing pressure.The rapid viscoanalyzer results revealed that the lily starch treated with UHP at 600 MPa showed low values of peak viscosity,trough viscosity,breakdown,final viscosity,and setback.These results indicated that UHP was an effective physical modification method for lily starch,UHP treatment（600 MPa,30min）caused nearly complete gelatinization of lily starch,and lily starch modified using UHP might expand the application of lily in the food field.2.Octenyl succinylated lily starch samples with the degree of substitution（DS）ranging from 0.0077 to 0.0269 were prepared.And then,the structure,physicochemical properties and rheological properties of OSA modified starch were studied.The characteristic peaks at 1570 cm^-1 and 1724 cm^-1 increased with the increase of DS,confirming the successful esterification and introduction of carbonyl into starch molecules.The modified lily starch granules were folded and depressed,and the grain size decreased.The esterification reaction mainly occurred in the amorphous region and surface of starch particles,and the crystal shape of starch did not change.The results of differential scanning calorimetry（DSC）showed that the internal interaction of starch molecules was weakened by the introduction of OSA group,which enabled starch particles to absorb water and expand at a relatively low temperature,and reduced the energy required for gelatinization.After OSA modification,the starch system showed shear thinning phenomenon with the increase of shear rate,and the starch system was pseudoplastic fluid.OSA modification changed the rheological properties of the starch system,and the n value decreased,while theσ₀ andκvalue increased.The hydrophobic groups were added by the modification and the hydrophilic properties were retained,resulting in amphiphilic biopolymers.According to these results,OSA lily starch has the potential to be used as emulsifier and stabilizer of emulsion.3.In this study,the original lily starch,the modified OSA-3 starch with the degree of substitution of 0.019,and the gelatinized OSA-3 modified starch（GOSA-3）were used to stabilize the emulsion,and the storage experiment was carried out for 9 days.The particle size of the three emulsions showed a bipeak droplet size distribution whether they were freshly prepared or stored.The particle size of the stable emulsion of Native starch was significantly larger than that of OSA-3 and GOSA-3.Compared with Native starch stable emulsion system,the blueness of OSA-3 and GOSA-3 starch stable emulsion system was lower,the color of OSA-3 starch stable emulsion system was darker,and the color of GOSA-3 starch stable emulsion system was brighter.In general,the emulsion stability of the emulsifier follows an ascending order:Native<OSA-3<GOSA-3.