Abstract:
In this paper, the starches from two distinctive plants, namely, the starch from Haimen taro (AAS) and the starch from Wangqiao fruit taro (CSS), were used as raw materials. With commercial sweet potato starch (SPS) as control, the physicochemical properties and
in vitro digestion characteristics were comparatively analyzed. Results showed that the purity of the three starches was relatively high. The amylose content of SPS (53.4%) was much higher than those of AAS (36.2%) and CSS (26.3%). Infrared spectroscopy analysis indicated that the values of short-range structural order index (
R1044/1022) of AAS and SPS were 0.91 and 0.92, respectively, which were significantly higher than that of CSS (0.79). X-ray diffraction results demonstrated that AAS was a typical A-type starch, while SPS and CSS were C
A-type starches. Scanning electron microscopy images revealed that AAS and CSS presented various shapes including spherical and irregular polyhedrons, with particle diameters of 6.1±1.9 μm and 3.1±1.2 μm respectively. Chain length distribution analysis revealed that the amylose molecular degree of polymerization of AAS was significantly lower than those of CSS and SPS. In the branched part, CSS had relatively more A chains and B1 chains, while SPS had the most B2 and B3 chains. In terms of physicochemical properties, the solubility, swelling power, thermal stability, and gel strength of AAS and CSS starch gels were all lower than those of SPS.
In vitro digestion characteristic analysis showed that before gelatinization, AAS contained approximately 22% rapidly digestible starch (RDS) and was the easiest to be digested. After gelatinization, SPS (containing approximately 30% RDS) was more resistant to the action of digestive enzymes, while the resistance to digestion of AAS and CSS was similar (both containing approximately 40% RDS). Therefore, AAS was an A-type starch with uniform particles at moderate particle size, and easy digestibility, while CSS was a C
A-type starch with smaller particles, slightly lower structural order, opaque starch paste, but better resistance to digestion. The research results can provide a reference for the development and application of these two new resource starches.