Studies On The Quality And Process Properties Of Soy-Fortified Wheat Flour Blends

Germination has been regarded as an inexpensive and effective technology for improving the nutritional quality of soybean. Three indexes were studied including GABA, phytic acid and soluble protein content on the germinated soybean, and optimized the best germination condition by fuzzy comprehensive evaluation and frequency analysis method; Meanwhile the flour quality, doughy processing character (noodles and steamed bread)were used to study the effect of adding whole or defatted soybean flour of germinated (best germination condition)or non-germinated soybean-at nine different additive levels(0,1.0,2.0,3.0,6.0.9.0,12.0,15.0,18.0)-to wheat flour. In addition, chemical bonds and microscopic structure were used to explore the influential mechanism of soybean flour on dough. The main research results of this paper are as follows:1.In order to get the high nutrition characteristic soybean flour with rich in GABA and soluble protein but poor in phytic acid, three elements quadratic current revolving design and frequency analysis method were adopted to optimize processing technology which were that germination time was36.43h～47.26h. germination temperature was22.6℃～25.5℃, soaking time was8.78h～11.32h.2. The ash, gluten index, gluten loss rate of composite flour had grown with increased the additive amount of four different type soybean flours(sprouted or non-sprouted whole soybean, sprouted or non-sprouted defatted soybean flour), while falling number, wet gluten content and sedimentation value had differently declined; The results of composite color date showed that the whiteness(H) of all type of composite flours showed a downward trend with increasing of soybean flour content, and that the color value L decreased, b increased but a had not significantly changed; The results of farinograph properties studies were showed that flour added with soybean flour (except sprouted whole soybean flour) resulted in higher values for water absorption, while firstly increased dough development and stable time and then shortened, there were significant differences between sprouted and non-sprouted soybean flour effect on the dough extensibility, maximum resistance and water absorption..3.Through changes on noodles and steamed bread quality as a result of the addition of germinated and non-germinated soybean flour comparative study found that:Chinese steamed bread had a degradation quality when germinated and non-germinated soybean flour exceeds3%, the main difference between the two flours is steamed bread flexibility, viscosity and smell; And both flours brought about more loss of cooking noodles meanwhile also caused the sensory score decrease such as apparent state,viscosity, toughness, especially when sprouted soybean meal content was over9%, the noodle quality seriously deteriorated. The correlation analysis indicated that there were significant correlation between the additive amount of soybean meal and index of noodles, steamed bread quality, especially the color of products typically affected by soybean flour.4. Free SH groups content in dough increased firstly and then decreased at the additive amount of soybean flour from0%to9%, the reverse variation tendency was found in disulfide bond. The starch granules of wheat dough appeared roundness or ellipse in shape and were surrounded by gluten protein membrane, and that starch granules of dough containing sprouted soybean meal presented disproportionately folding and hollow state. At the same time part of starch granules broken away from the protein membrane, making dough create irregular internal cavity. Relevant analysis about gluten quality and-SH/S-S clearly stated that there was significantly negative correlation between SH groups content and disulfide bond content, while gluten index, gluten losing and SH groups content were positively correlated.