Effect of dry heat treatment on multi-structure, physicochemical properties, and in vitro digestibility of potato starch with controlled surface-removed levels

Abstract

To explore the effect of the out-shell structure on dry heat modification efficiency on starch, chemical gelatinization technology was used to deshell the potato starch granules. The controlled shell-separated levels of approximately 10%, 30%, and 50% of the remnant were obtained. Further, starch samples were subjected to dry heat treatment (DHT), and the multi-structural, physicochemical, and digestibility properties were determined to investigate the shell separation process (SSP) effect on DHT. The results showed a rough and porous surface after SSP. Additionally, the larger ratio of long B chains (B2 and B3) and higher relative crystalline (RC) was revealed both in the superficial and core region of starch. Furthermore, after DHT, the solubility and amylose content were elevated, while the molecular weight, pasting viscosities, and enthalpy were reduced. Besides, DHT limited the accessibility of amylase to starch. Significantly, starch with a soft outer-shell structure exhibited a different trend after DHT than hard outer-shell, as evidenced by increased RC and slowly digested starch. These results may provide new insight into the structural arrangement within starch granules and expand the application of dry heat treatment.