Basic studies on the production of Yakifu Part VII - Scanning electron microscopic observation of expanded structure of Yakifu supplemented with different starches

Contributions of different starches exhibiting different effects on the exp ansion of yakifu and having different physicochemical characteristics were studied to expanded structure construction of yakifu. Granular starches inh ibited sequential, fibrous and sheet structure formation of gluten, resulti ng in network structure in gluten dough during kneading, while amorphous st arch didn't. Pregelatinized and soluble starch with higher swelling power i nterfered with homogeneous mixing of gluten and starch. Weil expanded produ cts contained well arranged air cells from bottom to top, but only poor air cells were formed in inferior products, In expanded products of synthesize d flour with high amylose corn starch or mung bean starch, starch granules were observed on the air cell walls. Isolated starches from the expanded pr oducts showed polarizing cross, indicating parts of those starches were res istant to the baking temperature. At the beginning of expansion, expanded g lutenous structure was covered with pasted starch to form closed individual air cell. These air cells were accumulated to give bigger specific volumes . With an increase in the proportion of gelatinized starch in the flour, th e specific volume was lowered. Therefore, it was concluded that granular st arches with appropriate swelling power which gelatinized during baking cont ribute the expansion of yakifu.