Characterization and in vitro digestibility of potato starch encapsulated in calcium alginate beads

Abstract

In this study, potato starch granules were encapsulated in calcium alginate beads (PS@CAB) with the aim of slowing starch digestion. The microstructure, gelatinization property, and in vitro digestibility of PS@CAB were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and in vitro simulated digestion experiment. The size of the fresh beads was about 2 mm and reduced to about 1 mm after drying. The encapsulation efficiency of starch was over 98%. Compared to the potato starch, the swelling power of PS20@CA2B decreased from 31.1 ± 0.4 g/g to 6.6 ± 0.4 g/g at 95 °C. DSC results showed that the peak gelatinization temperatures of potato starch encapsulated in the beads increased significantly (p < 0.05) with a maximum value a 69.87 °C, compared with potato starch (62.76 °C). The maximum value of enthalpy change was 11.47 J g−1, which was much higher than that of unencapsulated potato starch (7.56 J g−1). SEM images showed that potato starch granules were coated in beads by calcium alginate films. Moreover, slowly digestible starch and resistant starch contents in the beads increased to 27.5% and 18.3%, respectively, which were remarkably higher than those of potato starch without encapsulation (9.2%, 3.4%, respectively). This study proposes a new strategy for the slow digestion of starch by encapsulating starch granules in calcium alginate beads, which benefits people with type 2 diabetes or obesity.