Effect of Direct Extrusion Modification on the Structure and Nutritional Properties of Rice Analogues

Abstract

In order to improve the small intestinal digestibility of rice analogues (RA) and to enhance the nutritional value of the product, rice and potato flour blends were used as raw materials to prepare RA by direct extrusion modification using chemical or biological modifiers combined with high-temperature puffing. The internal structure and nutritional characteristics of RA were analyzed. The results showed that potato starch and amylase enhanced the digestive resistance of RA. The tested chemical modifiers mainly affected the structure and physicochemical properties of starch, in turn increasing the apparent viscosity and decreasing the degree of hydrolysis and digestibility of RA. Octenylsuccinic anhydride (OSA) played a promoting role in the initial stage of intestinal digestion. Propylene oxide (HPPO) reduced the particle size and increased the storage modulus (G’) of RA. Sodium trimetaphosphate (STMP) increased the particle size and G’ of RA. α-Amylase promoted the decomposition of large particles, led to even distribution of proteins on the surface of particles, and inhibited digestion. High-temperature expansion promoted starch decomposition in the early stage of intestinal digestion. Digestion results showed that the combinatorial effect of extrusion modification and high-temperature puffing weakened the film-forming capability of potato starch, which effectively inhibited the decomposition of the starch and weakened the digestive reaction when it just entered the intestine.

Keywords

• screw extrusion; rice analogues; chemical modification; α-amylase; in vitro digestion