Physical properties of daily foods and mastication

Abstract

先に平川らは米飯主食がパンやうどんを主食とする食事に比べ咀曙を促すことが出来ると報告した。本研究ではこの結果を食品物性の面から検索することを目的として,米飯と咀畷様式が米飯と共通するパン類の等速圧縮破断試験を行った。その結果,米飯は荷重0.60Nに破断点を持つなだらかな山形曲線を与え,曲線の形状から粘りがある米飯であると判定した。しかしパン類では,食パンでは荷重14.1N, ロールパンでは33.6Nでほとんど破断された。以上の結果から,パン類では圧縮破断のみの咀啜に対し,米飯の場合には更に(破断のための咀畷に加え),米飯の粘性特性に起因する食塊形成のための咀畷が必要であると考えられた。従って,米飯主食の食事における咀曙回数の促進要因は米飯の粘性によるものと考察した。Previously, Hirakawa et al. reported that cooked rice as main foods was able to promote more mastication in comparison with bread or udon noodles as main foods.In this study, for the purpose of searching their results from the viewpoints of physical properties of foods, we have made the uniform velocity compressive rupture tests of cooked rice and sorts of bread which have a type of mastication similar to that of rice, As the results, cooked rice gave a gently sloping curve which had the rupture point at the load value of 0.60N.From the shape of curve, it is judged that cooked rice is viscous. In case of bread, however, a leaf of bread was almost ruptured at the load value of 14.lN and a roll of bread at 33.6N.Based on the above results, we have considered that mastication is needed solely for compressive rupture in case of sorts of bread, and that, on the contrary, in case of cooked rice, more mastication is necessary to form a mass of foods caused by stickiness of cooked rice (in addition to mastication for rupture). It is, therefore, concluded that the promotion factor for the number of mastication times in taking a meal with cooked rice as main foods is originated in the viscosity of cooked rice