Preparation,Physicochemical Properties And Application Of Oxidized Starch By Cold Plasma

Oxidized starch is a crucially modified starch that finds extensive applications in the food,papermaking,and textile industries.The process of oxidation leads to a reduction in gelatinization temperature and viscosity while enhancing thermal stability.The oxidized starch exhibits excellent freeze-thaw stability and film-forming properties,rendering it a desirable thickener for food applications.Physical oxidation,as an eco-friendly modification technique,is currently the most prevalent method due to its utilization of solely water,heat and other resources while being safe and pollution-free.Mung bean starch contains 50%～60%content and is favored by consumers owing to its low energy value.In this study,mung bean starch was subjected to atmospheric pressure dielectric barrier discharge（DBD）oxidation.The impact of cold plasma treatment on the physicochemical properties,morphological structure,and digestibility of oxidized mung bean starch was investigated under various gas medium conditions,treatment voltages,and durations.Furthermore,the specific application of oxidized mung bean starch in bread-making was explored.（1）The effects of wet and dry oxidation treatment by dielectric barrier discharge（DBD）plasma on the oxidation degree of mung bean starch were investigated.The results showed that the effect of DBD plasma dry method is better than plasma-activated water（PAW）oxidation.So mung bean starch was oxidized by DBD plasma dry method in this paper.Treatment time was:2 min,4 min,and 6 min.Applied voltage was:35 V,45 V,and 55 V.Gas medium was:air and oxygen.The oxidized mung bean starch produced in both gas media met the requirements for the carboxyl content of oxidized starch as a food additive（less than or equal to 1.1%）.（2）The changes in physicochemical properties and morphological structure of mung bean oxidized starch under different plasma treatment conditions were investigated.Rapid viscosity analyzer（RVA）,differential scanning calorimeter（DSC）,Fourier transform infrared spectroscopy（FT-IR）and X-ray diffraction（XRD）were used to study the pasting properties,thermal properties,particle surface morphology and other physicochemical properties of mung bean oxidized starch.The results showed that plasma treatment generally improved the brightness of mung bean oxidized starch,reduced its p H value,and increased its solubility.The oil holding capacity for 2 min and 6 min was improved,and the transparency was generally improved in air medium.The T_O and T_P value generally increased with the increase of plasma treatment voltage,indicating that the structural transformation of oxidized starch improves the thermodynamic stability of starch crystals.The oil holding rate of individual samples increased significantly.The non-Newtonian fluid properties of oxidized mung bean starch remained unchanged.The apparent viscosity treated in oxygen medium was better.The consistency coefficient K decreased with the increase of treatment voltage.Under 35 V voltage treatment,the thickening ability of oxidized mung bean starch was improved.The R_1047/1022 values were higher,indicating that the order degree was improved,and the amount of amorphous structure and crystalline starch was reduced.XRD results showed that C-type crystal structure of oxidized mung bean starch remained unchanged,and the relative crystallinity increased significantly,indicating that plasma treatment had a significant effect on the crystalline and amorphous regions.No free radical signal was detected in all samples.SEM results showed that with the increase of plasma treatment voltage,the degree of oxidative corrosion of mung bean starch increased,some starch was degraded,the degree of polymerization decreased,and the particles were broken into smaller granules.（3）The changes in vitro digestibility and the application of bread under different plasma treatment conditions were studied.Three samples with higher contents of slowly digestible starch（SDS）and resistant starch（RS）were:35 V,2 min and 35 V,2min,O₂,45 V,4 min,O₂.These three samples were selected to explore the effect of mung bean oxidized starch on bread quality.The b^*value of bread decreased,while the absolute value of a^*increased,and the L^*did not change significantly,indicating that the plasma-treated starch did not promote the Maillard reaction under the same baking conditions.The texture analyzer results showed that the texture characteristics of bread were greatly improved by adding oxygen medium oxidized mung bean starch.According to the comprehensive sensory evaluation analysis and the last overall favorability collection of the sensory evaluation table,the most popular of the four bread samples was made by mung bean oxidized starch at 35 V,2 min under oxygen medium treatment.