Physical Characteristics of Mochi

Abstract

The physical characteristics after aging of Mochi prepared by several methods were studied, and the following results were obtained:. 1) Mochi prepared by stamping exhibited much of the initial rice grain structure, while that prepared by a power mixer was of a well-mashed paste form rather than rice grain tissue. 2) The hardness of each type of Mochi measured by a rheolometer depended on the storage conditions : Mochi prepared by a mixer was softer than by stamping with no storage, while that prepared by a mixer was harder than by stamping after storing for 3 hr at 5°C. 3) The creep curves of Mochi measured by a rheoner could be explained by a six-element mechanical model consisting of Hookean body, two pairs of Voigt bodies and a Newtonean body. The shift factor-1/T relationship for Mochi stored at °C resulted in two straight lines, a refraction point being observed at 50°C ; however, no such phenomenon was observed for Mochi stored at-20°C. 4) The cooking loss of Mochi stored at 5°C decreased with increasing storage time, while that of the Mochi stored at -20°C hardly changed . Mochi prepared by stamping showed a small cooking loss after storage at 5 and -20°C, respectively. 5) The crystalline structure of raw glutinous rice could be classified as a type-A pattern, although this pattern disappeared upon heating and was transformed into a type-B pattern after storing at 5°C for one week. In the case of Mochi stored at -20°C, the crystallinity was never recovered. 6) The viscosity of Mochi measured by a Brabender viscograph after storing at 5°C showed a maximum value of 800 to 1000 B. U., while that stored at -20°C showed a maximum value of 200 to 300 B. U. The viscosity of the latter reached a peak after storing for 72 hr, and then decreased with a further period of storage.