Octenyl Succinic Anhydride Modifications Of Aqueous-ethanol Heat Treated Corn Starch And Its Application

Octenyl starch succinate（OSAS）is a starch modified by octenyl succinate（OSA）esterification,and is widely used for its excellent emulsification properties.However,natural starch has a dense particle structure,and the double helix is formed by intermolecular hydrogen bonds between the starch chains inside the granules,which constitutes a crystalline region,and the reactivity is low;at the same time,the solubility of OSA in water is low,and the OSAS prepared by the traditional aqueous phase method has high safety,but the reaction efficiency is low,the DS is low,and the product application performance is poor.Therefore,how to safely and effectively activate starch granules and improve their esterification activity is currently a research hotspot in the preparation of OSAS.Taking natural corn starch as raw material,the double helix crystalline structure of natural corn starch was converted into a single helix V-shaped crystalline structure by using aqueous-ethanol heat treatment,which improved the reactivity of starch,and the conditions for esterification reaction were further optimized by univariate-response surface optimization design experiments,and OSAS with a high degree of substitution was prepared under the condition of OSA addition of 3.0%,and a stable emulsion was prepared by using the above-mentioned optimal OSAS,and finally the emulsion was used to embed the functional factor octacosanol（OCT）,The effect of emulsion embedding was verified by animal experiments.The main conclusions are as follows:Firstly,the NMS was activated by aqueous-ethanol heat treatment,and the activation starch esterification was prepared to prepare OSAS,and the effects of aqueous-ethanol heat treatment on starch structure,DS and reaction efficiency of OSAS were studied.The results show that in the 50%ethanol solution,with the increase of the heating temperature,the NMS particles are obviously swelled,the face wrinkles are broken,and the depression is noted,and when the heating temperature reaches 80°C,the NMS crystalline structure is changed from A-type to V-type,the adsorption performance of starch is enhanced,and the diffraction intensity of the active hydroxyl group is enhanced by Raman spectroscopy,indicating that the NMS is activated;at this time,when the NMS concentration increases to 30%,the starch oil absorption rate and water absorption rate reach 223.24%,1335.62%,respectively.And the diffraction intensity of the active hydroxyl group is the highest.The degree of substitution（DS）of OSAS obtained after further esterification of 20%OSA was as high as 0.2259,the reaction efficiency was 146.40%,and compared with the untreated NMS,the DS and reaction efficiency were increased by 110.77%and 111.96%,respectively,indicating that the optimal thermal treatment conditions for alcohol water were:ethanol concentration of 50%,heating temperature of 80°C,starch milk concentration of 30%.Then,taking the activated starch obtained under the above optimal aqueous-ethanol heat treatment conditions as raw materials,according to the relevant provisions of GB28303-2012,the fixed OSA addition amount was 3.0%,and the conditions for esterification reaction were optimized by univariate-response surface optimization design experiment.The results showed that the optimal esterification reaction conditions for OSAS were:starch milk concentration of35%,reaction temperature of 40°C,reaction time of 3.8 h,p H 8.7,and the DS of OSAS obtained under this condition was 0.0670.The results showed that in 50%ethanol,when the starch concentration was 30%and heated at 80°C for 30 min,the DS of OSAS obtained by further esterification by adding 20%OSA was as high as 0.22,and the reaction efficiency was 146.40%.The properties of activated NMS and NMS were compared by optical microscopy,SEM,XRD,RS and other instrumental analysis methods:compared with NMS,after the alcohol and water heat treatment NMS,the particles of the activated starch were obviously swollen,the surface wrinkled and ruptured,and the crystalline structure changed from the A type of NMS to the V type,the relative crystallinity was significantly reduced to 14.11%,and the oil absorption rate and water absorption rate reached 223.24%,1335.62%,respectively.RS shows an increased diffraction intensity of the active hydroxyl group and an enhanced diffraction intensity of amylose V.The name of the alkoxide heat treated starch sample obtained under this condition is NMS-80°C-30%.Then,taking NMS-80°C-30%as raw materials,according to the relevant provisions of GB2760-2014,the fixed OSA addition amount was 3.0%,and the conditions for the esterification reaction were optimized by the one-way-response surface optimization design experiment.The optimization conditions are:the NMS-80℃-30%concentration is 35%,the reaction system p H is 8.7,and the reaction is 3.8 h at 40°C,and the DS of the obtained OSAS_80℃-30%can reach 0.0670.Then,taking the emulsification stability index（ESI）as the index,the water-infused oil-in-oil emulsion was prepared with OSA added 3.0%and OSAS_80℃-30%with a DS of 0.0670 as the emulsifier,and the preparation conditions of the emulsion were optimized by one-way experiment,and the optimal emulsion ratio was OSAS_80℃-30%:oil:water=1:2:22,The optimal homogenization speed is 1.2×10⁴ r/min and the optimal homogenization time is 5 min.Using the pack capacity of OSAS_80℃-30%emulsion,the functional factor octacosanol（OCT）was packed,the packing capacity of OCT was optimized,and the stability of the optimal pack system under different ion strengths,temperatures and p H was explored,and the results showed that 50 g OSAS_80℃-30%emulsion could stably pack 125 mg OCT,The OSAS_80℃-30%emulsion-packed OCT system has good tolerance to alkaline environments,and its stability decreases under the conditions of acidic environments and increased ion concentrations.Finally,an experimental animal model of physical fatigue induced by chronic bondage stress was used.Compared with the dispersant-dispersed OCT,the OSAS_80℃-30%emulsion-packed OCT system better alleviated the weight loss of mice under chronic restraint,enhanced the exercise endurance of fatigue mice,prolonged the time of fatigue weight-bearing swimming,reduced the lactate level generated by mice after exercise,and improved the ability of mice to accumulate muscle glycogen and liver glycogen compared with the dispersed OCT dispersed by dispersion.The results of animal experiments show that the bioavailability of OCT after emulsion encapsulation is improved.