The Changes in Structural, Physicochemical, and Digestive Properties of Red Adzuki Bean Starch after Repeated and Continuous Annealing Treatments

Abstract

Red adzuki bean starch-water suspensions (1:3, w/v) are subjected to repeated and continuous annealing treatments at 55 C for 96 h. The changes in structural, physicochemical, and digestive properties of starch after both treatments are studied and compared. The results show that the repeated and continuous annealing increases the relative crystallinity of starch without influencing the morphological structure and crystalline patterns. Gelatinization temperatures and enthalpy increase; however starch solubility, swelling power, and viscosity decrease after both annealing treatments. FT-IR analysis shows that annealing treatments result in a reorganization of starch molecules and improve the crystalline perfection. Furthermore, the applied annealing treatments decrease the enzymatic susceptibility of starch and increase the percentage of slowly digestible and resistant starch present. Generally, the repeated annealing results in modified starch with good functionalities compared with continuous annealing. Therefore, repeated annealing can be recommended for producing of modified starch for industrial applications.

The Comparison of Structural, Physicochemical, and Digestibility Properties of Repeatedly and Continuously Annealed Sweet Potato Starch

“…Compared with the native starch, the RDS level of the annealed samples became lower with the increase of annealing cycles and time, but the RS, SDS (except the samples of CANN‐96), and the RS + SDS level gradually increased (Table ). These results were in agreement with that of the red adzuki bean starch (Xu et al., ). However, the RS content of the annealed navy and pea bean starch decreased after annealing treatment (Chung et al., ).…”

“…From the findings, it was suggested that the solubility and swelling power of sweet potato starch gradually decreased with the increase of the number of cycles or time of annealing (Table ). These results were in agreement with the solubility and swelling power of red adzuki bean starch (Xu et al., ). This could be attributed to the formation of the amylose–lipid complexes and a more ordered structure of the amorphous regions (Chung, Liu, & Hoover, ; Waduge et al., ).…”

“…Figure B showed that the DSC curve of the annealed starch samples changed obviously compared with that of the native starch samples, the peak temperature increased, and the DSC curve became narrower after annealing treatment. This same trend was discovered in red adzuki bean starch (Xu et al., ).…”

“…These two values gradually increased with the increase of annealing cycles or time (Table 3), which showed that the starch cold paste stability was poor and easily regenerated. These results were consistent with the results reported by Xu et al (2018b).…”

“…The RANN starches exhibited greater relative crystallinity, thermal stability, pasting temperature and SDS content of the potato starch compared with CANN ones (Xu et al., ). By contrast, CANN starches of the red adzuki bean had a greater relative crystallinity than RANN ones (Xu et al., ). The differences in these consequences may be attributed to the difference in the structure of the starch, which has a great relationship with these factors such as amylose content, particle size and starch sources.…”