Study Of Influences Of Acetylated Hydroxypropyl Starch On The Fast-frozen Dumplings Quality

With corn starch and potato starch as raw material, the properties of acetylated hydroxypropyl starch were studied in this thesis. The effect of wheat flour on the quality of fast-frozen dumplings wrapper and acetylated hydroxypropyl starch on rheological properties of dough, as well as the cooking, sensory evaluation and texture characteristics of fast-frozen dumplings were explored. The results are as follows:Under the same reaction conditions, the degree of substitution of potato starch by acetylated hydroxypropyl dual-modification was higher than that of corn starch. As the degree of substitution increased, paste transparency, dissolution rate and expansion rate, retrogradation stability and freeze-thaw stability of acetylated hydroxypropyl starch were gradually increased. All the properties of potato starch were better than corn starch.Combined with the characteristics of high quality flour, sensory index and cooking characteristics of fast-frozen dumplings wrapper, the optimal dient contents of flour to make fast-frozen dumplings are as follows:moisture content less than14.5%, protein content more than11%,28%-35%gluten,50mL-55mL precipitation values,61℃-63℃gelatinization temperature, the peak viscosities more than1200BU,58%-65%absorption ratio,3-6min development time; the stability time and valorimeter value should be more than3.5min and50,400BU-550BU stretch resistance respectively; the extensibility and stretch energy should be more than15cm and100cm2respectively.The results of pasting properties showed that:as the degree of substitution and proportion of acetylated hydroxypropyl starch increased, the gelatinization temperature and gelatinization complete temperature of flour declined and the peak viscosities of paste increased.The results of flour properties indicated that:When the percentage of acetylated hydroxypropyl starch was10%, the acetylated hydroxypropyl dual-modification was MS0.12, DS0.04and MSO.14, DS0.04, the improvement of mixed flour was more significant. But with the proportion increasing, the dough properties were getting worse.The results of stretch properties revealed that:with the proportion of acetylated hydroxypropyl starch increasing, the maximum stretch resistance, stretch energy and extensibility of dough was declined. When the percentage was5%, hydroxypropyl modification substitution was greater than0.12and acylation modification substitution was less than0.07. The maximum stretch resistance, stretch energy and extensibility of dough were relatively large.The result of cooking properties made it clear that:with the addition of acetylated hydroxypropyl starch, the optimum cooking time was shortened, the rate of water loss and cracking rate was reduced, the transparency of dumpling soup was improved. As the degree of dual-modification increased, the cooking characteristics were obviously improved. When the adding amount was5%, it was good for the cooking, but more of it would give rise to an increase of the cracking rate of fast-frozen dumplings.The results of texture properties magnified that:When the percentage was5%, as the degree of modification of acetylated hydroxypropyl starch increased, the hardness, gumminess, springiness and chewiness of dumplings wrapper were gradually improved.It was manifested that:the acetylated hydroxypropyl starch with higher modification degree could effectively improve the quality of gluten, so the shear parameters increased significantly. Adding the acetylated hydroxypropyl starch with lower modification degree, the shear parameters was obviously lower than the control group, resulting in a decline in the quality of dumplings wrapper.The results of sensory evaluation indicated that:when the percentage was5%, different substitution of acetylated hydroxypropyl starch has certain influence on the sensory quality of fast-frozen dumplings, with the increase of dual-modification, the value of sensory evaluation was greater.