Boiled rice-dumpling, “Chimaki, ” wrapped in lye-treated bamboo leaves exhibits yellow color.
Glutinous rice soaked in water was wrapped in bamboo leaves and boiled for half an hour either in water itself or in water contained lye, and the coloration of these materials was compared. Furthermore, pulverized bamboo leaves and rice were boiled either in water or in 1% solution of potassium carbonate, and the aqueous extracts were further extracted with ethyl ether and ethyl acetate. The coloring matters in each fraction were investigated by means of paper chromatography and UV spectroscopy.
The flavonoid pigments including kaemferol, rutin, quercetin-3-glucoside and quercitrin were identified from bamboo leaves and quercetin and quercitrin from rice.
It was found that rice grains were colored when they were boiled either in alkaline extract of the bamboo leaves or in alkaline solution alone.
It was clear that the coloration of the rice-dumpling wrapped in bamboo leaves were due to the coloration of the flavonoid pigments transferred from bamboo leaves as well as from pigments originally presented in rice itself.
抄録全体を表示