抄録
Experiments were performed to investigate why the acridity of spinach boiled in salted water was weak, even though most of the oxalic acid, the bitter taste ingredient, remained. The influence on acridity of pectin and cellulose was also investigated, these being components of the cell wall and the main ingredients of vegetables.
A sour taste was perceptible in an oxalic acid solution with a concentration of 0.5-1 mM, and a taste different from that of water was experienced from a potassium oxalate solution of less than 5 mM concentration. Acridity was apparent with a 2.5 mM oxalic acid solution, and strong acridity was present at 10 mM. There was slight acridity in 5-10 mM potassium oxalate, and this was clearly apparent at more than 50 mM. NaCl added to the oxalic acid solution tended to weaken the acridity at 50 mM, and there was a significant effect on the acridity at 100 mM NaCl.50 mM NaCl added to a 100 mM potassium oxalate solution significantly weakened the acridity. The acridity of a 5 mM oxalic acid solution was significantly reduced when pectin was added due to the viscosity of pectin. It is suggested that the weakened acridity by adding NaCl to spinach was due to inhibition by the salty taste and to the viscosity of pectin.
