Extraction of starch and proteins from the tubers of large-grain Cyperus esculentus L.

摘要

The contents of starch in the tubers of Cyperus esculentus L. were determined by the iodine method, and those of proteins were determined by the Coomassie brilliant blue G-250 method. Starch and proteins were simultaneously extracted by the lime water immersion method, and the effects of material-liquid ratio, immersion solution pH value, immersion time and supernatant pH value on the extraction efficiencies were studied. The optimal parameters were obtained by orthogonal experiments. The results show that the contents of starch and protein in large-grain C. esculentus are 35.4% and 6.3%, respectively. The optimal extraction conditions for starch include: immersion solution pH = 11.0, material-liquid ratio = 1:4 (w:v), immersion time = 70 min. The optimal extraction conditions for proteins include: immersion solution pH = 10.5, material-liquid ratio = 1:5 (w:v), immersion time = 50 min. Proteins were precipitated from the supernatant at pH 5.5.