Study On Preparation, Property And Application Of Acetylated Microcrystalline Potato Starch

In order to improve the properties of potato starch and enlarge its application field, potato starch was modified by a micro-crystallization and acetylation composite method.The acetylation technology parameters of microcrystalline potato starch were optimized by the Box-Behnken method, using potato starch as the raw materials, hydrochloric acid as the acid hydrolysis reagent, acetic anhydride as the acetylation reagent and sodium hydroxide as the catalyst. Furthermore, the property and application of acetylated microcrystalline potato starch were studied. The effect of some factors such as the reaction temperature, reaction time, pH and amount of acetic anhydride on the substitution degree of the acetylated microcrystalline potato starch were investigated. The substitution degree of acetylated microcrystalline potato starch was determined by the saponification method. At the same time, the granular structure, thermal property and microcrystalline structure of the acetylated microcrystalline potato starch were characterized by the infrared spectrogram (IR), thermo gravimetric analyzer (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD), respectively. The granular structure of the acetylated microcrystalline potato starch was observed by a polarization microscopic. The mechanical properties of the starch films were investigated further.The results showed that the best technology conditions for preparing the acetylated microcrystalline potato starch were:reaction temperature30℃, reaction time90min, pH8.5and amount of acetic anhydride17%(mass percentage ratio of acetic anhydride to the dry microcrystalline starch), respectively.After potato starch was modified by the micro-crystallization and acetylation, its acid resistance, alkali resistance, cold and hot viscosity stability increased, but its retrogradation, freeze-thaw stability and blue value decreased. After potato starch was modified by the micro-crystallization, its expansion capability decreased. After potato starch was only modified by the acetylation, however, the expansion capability increased. After potato starch was modified by the micro-crystallization and acetylation, the order of the thermal stability from strong to weak was as follows:microcrystalline potato starch, acetylated microcrystalline potato starch, potato starch. The peaks in DSC curves of potato starch, microcrystalline potato starch and acetylated microcrystalline potato starch were endothermic peaks. The structure of potato starch and microcrystalline potato starch belonged to a B-type. The acetylation affected the crystalline structure of the potato starch granules. The Maltese cross on the potato starch granules was distinctly observed, and the shape of the starch granules was ellipsoid. The potato starch granules were disrupted by the micro-crystallization, and the Maltese cross was reduced as well.After potato starch was modified by the acetylation, the tensile strength of its film reduced, but the extension length increased. After the film was prepared by mixing the acetylated microcrystalline potato starch with the acetylated potato starch in proportion, its tensile strength and extension length were increased.