BASIC STUDIES ON THE PRODUCTION OF YAKIFU.5. EFFECT OF AGING OF GLUTEN-DOUGH ON THE EXPANSION OF YAKIFU

The effect of aging of gluten-dough on the specific volumes of expande d products was studied. Before baking, gluten-dough was subjected to a ging at various temperatures. Among the temperatures tested, incubatio n at 60 degrees C for 20 min gave the highest specific volume. Incubat ion at 70 degrees C seemed to lead partial denaturation of gluten and gelatinization of starch, resulting in lower values of specific volume . Aging effects were studied at temperatures of 10 degrees C or 30 deg rees C for up to 30 hrs. When gluten-dough aged at 10 degrees C was ba ked, longer the aging length was, bigger the specific volume was. Agin g at 30 degrees C gave a different result. Specific volume became bigg er until 8 hrs of aging, while prolonged aging gave smaller volume and 24 hrs and longer aging resulted in no expansion. The appearances of expanded products obtained by baking aged gluten-dough were spherical, plump and soft to the touch. The vertical section of the expanded pro duct was packed with honey-comb structure, although one from gluten-do ugh aged more than 24 hrs at 30 degrees C was small, compact and hard to the touch and had no honey-comb structure in vertical section. The gluten-dough aged at 30 degrees C for more than 10 hrs became exhauste d and sticky, finally losing structural characteristics of dough. Some parts of gluten and starch seemed to be attacked by enzymes during in cubation especially at 30 degrees C. Certain degree of gluten degradat ion seemed to promote the expansion of yakifu when aged at 30 degrees C. This was not true in the case of aging at 10 degrees C. From the re sults obtained in this study, it was concluded that two types of aging effects occurred in gluten-dough incubated at 10 degrees C or 30 degr ees C.