| Acetate starch,also known as acetylated starch,is an important natural polymer modified product.Due to the presence of the hydrophilic acetylation group,the film-forming property,light transmittance,freeze-thaw stability and the like of the acetate starch are greatly improved compared with the original starch,and are widely used as a thickener,especially in the food industry.GB2760 "National Standards for Food Safety" Standards for the Use of Food Additives stipulate that acetate starch can be used in various foods,and the amount of addition can be used according to the production needs.The reaction efficiency of acetate starch is closely related to its economic benefits,environmental protection drainage,and quality stability.The amount of drug residues in food additives is also closely related to food safety.The process technology for preparing acetate starch by using vinyl acetate has been widely reported,but it is generally shown that the reaction efficiency is low.Therefore,it is of great significance to find a more optimized process condition in the industrial production of acetate starch.This project intends to optimize the experimental scheme to prepare vinyl acetate starch with high reaction efficiency,and investigate the effect of sodium tripolyphosphate(STPP)on the performance of vinyl acetate starch.The main research contents are as follows:(1)Taking the reaction efficiency of acetyl group as the evaluation index,the effects of STPP addition amount,reaction pH value,reaction temperature,reaction time and VAC addition amount were investigated.The results showed that within a certain range of reaction conditions,VAC-SB Compared with VAC-SA,the reaction efficiency is obviously high,and the reaction conditions are suitable for industrial production.On the basis of single factor experiment,the fixed amount of STPP was 3%,the amount of vinyl acetate added was 4%,and the response surface was determined by three factors:reaction pH,reaction temperature and reaction time to optimization experiment.(2)The prepared vinyl acetate starch was characterized by infrared spectroscopy,nuclear magnetic resonance,scanning electron microscopy and the like.The results showed that FT-IR showed that the esterification group was inserted into the starch,and the VAC-SB did not access the phospholipid bond(-P)group;1HNMR showed that the absorption peak of the methyl peak appeared,indicating that the starch was successfully esterified;SEM It shows that there is no significant difference in the apparent morphology and particle size distribution between the original starch and the vinyl acetate starch.The denaturation reaction occurs in the amorphous region of the starch molecule;TGA shows that the vinyl acetate starch has higher thermal stability.(3)By examining the gelatinization viscosity value,freeze-thaw stability,sedimentation value and other indicators,the difference in properties of vinyl acetate starch was further verified.The results showed that STPP had a certain influence on the performance of vinyl acetate starch.From the gelatinization viscosity analysis,VAC-SB has a lower gelatinization temperature and higher peak viscosity than VAC-SA,the difference is 1.2? and 73 BU respectively;from thermal stability analysis,VAC-SB and VAC-SA is superior in performance;from the analysis of light transmittance and sedimentation value,both VAC-SB and VAC-SA exhibit certain weak cross-linking properties;from freeze-thaw stability analysis,performance of VAC-SB and VAC-SA It is obviously superior to the original starch;from the acid resistance analysis,the performance of VAC-SB and VAC-SA is significantly better than the original starch.(4)The starch was applied to the bread making,the texture analysis was carried out by TPA analyzer and the bread was subjected to sensory evaluation.The results showed that the TPA data increased significantly after the bread was placed for 24 hours,and the hardness,elasticity and chewiness index the highest is VAC-SB,the minimum is VAC-SA,and the comprehensive evaluation results of the bread with VAC-SB added from the bread sensory evaluation index analysis are better.Comparison of vinyl acetate starch and raw starch shows that vinyl acetate starch has better application performance for bread. |
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