The effect of thermal and enzymatic degradation on the physicochemical properties and in vitro digestibility of canna starch

Abstract

The effect of thermal and enzymatic degradation on the physicochemical properties and in vitro digestibility of canna starch was investigated. Microscopic observation reveals that pores approximately 1 µm in diameter were obvious on the surface of enzymatically degraded canna starch (EDCS), and the formation of the cavum was found in the center of the starch granules. Physicochemical properties show that a transformation from soluble to insoluble amylose was observed in the thermal degraded canna starch (TDCS), and a sharp increase in water solubility index (WSI) was found in EDCS. The highest content of resistant starch (RS) (40.05%) was observed in EDCS-3, which was evidenced by the reappearance of soluble amylose in EDCS-5. As a whole, thermal degradation simultaneously perfected the crystalline structure and facilitated the process of gelatinization. Enzymatic degradation, on the other hand, is a net result of thermal and pure enzymatic degradation, and therefore resulted in a much more complex degradation pattern.