Author(s)： Yiming Feng, Youngsoo Lee
The effect of specific mechanical energy (SME) on in-vitro digestion and physical properties of extruded rice-based snacks was investigated in this study. Whole grains of medium grain brown rice (BR), medium grain sushi rice (SR) and long grain jasmine rice (JR) were extruded to prepare the rice-based snacks using a single screw extruder without additional thermal energy input. SME during extrusion was varied by changing feed moisture content. The feed moisture content (wet basis) was 9.99% – 12.55% for BR, 11.37% – 13.92% for SR and 12.42% – 14.39% for JR, respectively. Six extruded samples of each type of rice with different SME were collected and analyzed. With the decreasing SME, all three types of rice-based snacks showed significant decreases (p < 0.05) on rapidly digestible starch (RDS) and significant increases (p < 0.05) on slowly digestible starch (SDS). Physical properties, including expansion ratio (ER), bulk density (BD) and fracture energy (FE) were found to be highly correlated to SME. The results indicated that SME has significant effects on in-vitro digestibility and potentially glycemic index of extruded rice snacks. SME also can be an indicative parameter for the physical properties of rice-based extruded snacks.
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