Characterization of starch from bamboo seeds

Abstract

This study aimed to characterize structures, physical properties, and enzymatic‐hydrolysis rate of starch isolated from bamboo seeds (Phyllostachys heterocycla var. pubescens (Mazel) Ohwi) in comparison with that of indica and japonica‐rice starch. The bamboo seeds consisted of 68.2% starch (dry basis, db), which was lower than the indica and japonica‐rice kernels (85.1 and 87.1%, respectively). The bamboo‐seed starch also had compound granules, with morphology and sizes comparable to the rice starches. The bamboo‐seed amylopectin had a similar branch‐chain‐length distribution to the indica‐rice amylopectin, and both had longer average branch‐chain length (DP = 19.1 and 19.7, respectively) than the japonica‐rice amylopectin (DP = 17.1). The bamboo‐seed and indica‐rice starches showed higher onset gelatinization temperatures (To = 68.9 and 71.9°C, respectively) and gelatinization enthalpy changes (ΔH = 14.2 and 15.3 J/g), larger percentages of retrogradation (57.1 and 55.4%), but slower enzymatic‐hydrolysis rates (50.6 and 46.3% at 24 h) than the japonica‐rice starch (56.4°C, 14.0 J/g, 11.4%, and 66.2%, respectively). The bamboo‐seed starch displayed a higher pasting temperature but substantially lower viscosity than the rice starches, which could be attributed to its larger amylose content and smaller molecular weight and gyration‐radius of the amylopectin.