Study On The Preparation Of Long Chain Fatty Acid Starch Esters By Solid Phase Reaction And Its Properties

The synthetic technology and applications research of the long chain fatty acid starch esters has got much attention on scholars,because the long chain fatty acid starch esters had a good solubility,transparency,emulsification and biodegradable.The traditional methods of etherification mainly include water phase,organic solvent phase and enzymatic method,but there are some problems such as environmental pollution and energy waste,and it is difficult to deal waste water and other issues.Therefore,it is great significance to find a green way to synthesis starch esters.In this paper,using cassava starch as raw material,palmitic acid as etherification agent,palmitate starch ester(PS)was prepared by two ways of mechanical activation and mechanical activation-Microwave,the effects of different synthesis methods esterification of starch was studied by physicochemical and structural.In addition,the lauric starch(LS),stereate starch(SS)are prepared by two ways in their best conditions to find the rules of esterification.The main research contents and results are as follows:(1)Study the process conditions of PS were prepared by mechanical activation.Through the single factor experiments and the orthogonal test,the influences of mechanical activation(MA)time(tM),dosages of esterifying agent and catalyst,reaction temperature(Tr)were investigated respectively-by using Degree of substitution(DS)as evaluating index.The results indicated that the optimal parameters for the preparation of P S with a DS-value of 0.0108 were as follow:dosage of esterifying 12.0%,tr 60min,Tr 60? and dosage of catalystl.0%.(2)Study the process conditions of PS prepared by mechanical activation.Through the single factor experiments and the orthogonal test,the influences of mechanical activation(MA)time(tM),microwave time(tw),microwave power(Pw),material moisture(Ww)were investigated respectively by using Degree of substitution(DS)as evaluating index.The results indicated that the optimal parameters for the preparation of PS with a DS value of 0.0159 were as follow:mechanical activation time 60min,microwave time 2.0min,microwave power 800W,material moisture 24%.(3)Take the palmitic acid as etherification agent,the physicochemical properties and structure characterization of PS were compared.PS was prepared by mechanical activation(MA-PS),PS was prepared by mechanical activation-Microwave(MA-M-PS).The results of properties showed that the solubility,transparency of MA-PS were reduced,to the contrary,the viscosity,freeze-thaw stability,emulsifying of MA-PS were increased.Starch-iodine complex absorption curves indicated that absorption value become smaller and the maximum absorption wavelength shifted towards shorter.The results of structural characterization showed that:SEM,XRD,IR spectra indicated that the central of starch was depressed and broken under the mechanical force,crystallinity was reduced,the absorption peak of carboxyl was increased,and theMA-M-PS is obviously than MA-PS.(4)The lauric starch(LS),palmitic starch(PS),stereate starch(SS)are prepared by two ways in their best conditions,the rules of esterification of different chain length fatty acid was studied.The results showed that with the fatty acid carbon chain is increased,the hydrophobicity of the more prominent,the solubility and transparency were reduced,but the emulsifying properties have improved.In addition,the IR spectra showed that absorption peaks of carbonyl group(C=O)appeared at 1749cm-1 in the infrared spectra of products,and with the increase of carbon chain,ester peak decreased.