| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 92 === Abstract
Waxy rice flour is an important raw material for traditional Chinese foods. It is necessary to understand the physicochemical properties of cooked waxy rice products for process design and quality control. Effects of heating conditions (time, temperature and moisture content ), agitation and pounding on physicochemical properties of cooked waxy rice products have been investigated by using different scanning calorimerty (DSC), oscillatory rheometer and scanning electronic microscope (SEM).
Raising temperature or increasing moisture enhanced the starch gelatinization, which affected the microstructure of products. When the degree of gelatinization (D.G.) was lower than 50%, there was no network formed in the products. The network always exists at D.G. no less than 80%. High moisture content (80%) was helpful for forming network when the D.G. ranged from 50 to 80%. The mechanical action (agitation and pounding) resulted in the decrease in G’ and G”, helpful for forming network structure. The higher moisture content would increase the number of porous. At 45% moisture content, pounding wouldn’t lower the bulk density obviously. Both pounding and agitation would enhance the network structure and more pounding or agitation would resulted in more porous. The product with 55% moisture content, the network structure would be destroyed when pounding is more than 500 times. It also shows that the preference index and network structure are positive relation. At 65% moisture content, pounding and agitation would be helpful for lowering bulk density but not forming the network structure. Furthermore, it would also lower the value of preference index.
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