| Summary: | 碩士 === 國立嘉義大學 === 食品科學系研究所 === 102 === Rice is one of the most important food crops in the world as well as in Taiwan. With the economic development and changes of dietary habit and life style in Taiwan, the domestic consumption of rice is gradually decreased because wheat products are gaining more market share as the staple foods and snacks. Rice flour produced by grinding polished rice is commonly used as the ingredients for traditional Chinese foods. In addition to using in baby food and breakfast product, rice flour is also increasingly applied as wheat flour substitutes in recent years. Since rice flour lacks gluten-like material, the rice flour-water dough cannot have the viscoelastic properties similar to the wheat flour dough and the hydrogel of rice flour is relatively weak. Based on the above factors, rice flour alone can hardly be used to produce noodle like products as wheat flour. Transglutaminase (TGase) can catalyze the cross-linking between a peptide-bound glutaminyl residue and a ε-amino group of lysine residue in protein. It is reported that glutenin of rice has more cysteine content and the addition of TGase can increase number of connections for cross-links in rice protein. Novel technology to develop new products based on the rice flour can increase the consumption of rice in Taiwan.
This study investigated the use of domestic Indica and Joponica rice flour as the main ingredient to produce rice noodles with the addition of different levels (0%, 0.5%, 1%, 1.5%, 2% ) of TGase preparation (50 ~ 80 unit/g). The physicochemical and mechanical properties including color parameters, cooking loss, cooking gain, hardness, cohesiveness, and gumminess of noodles were investigated. The addition of TGase in the rice noodle formula conferred the yellowness of rice noodle which is more popular as for the quality of noodle-type products. On the other hand, TGase reduced the cooking yield and cooking loss. But in terms of texture characteristics, addition of TGase could increase hardness, cohesiveness, gumminess, chewiness, resilience and springiness of cooked Indica rice noodles with significant positive correlation. For cooked Joponica rice noodles, the addition of TGase increased the hardness, cohesiveness, gumminess, chewiness, resilience and springiness with significant positive correlation; but the cohesion showed significant negative correlation. Moreover, relatively high stickiness of rice noodle was observed when Joponica rice flour was used. Collectively, TGase could be effectively to improve the quality of rice noodles.
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