Effect of Specific Mechanical Energy on <i>In-Vitro</i> Digestion and Physical Properties of Extruded Rice-Based Snacks

Abstract

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.

Effect of Extrusion on Physicochemical Properties, Digestibility, and Phenolic Profiles of Grit Fractions Obtained from Dry Milling of Normal and Waxy Corn

“…Onwulata and others () mentioned that ER of corn extrudates decreased with an increase in protein content due to the decrease in the elasticity. The presence of more fat caused the lubrication of extruder barrel that might decrease barrel temperature during extrusion due to which a decrease in friction as well as degree of starch gelatinization occurred (Feng and Lee ) that ultimately caused reduction in expansion. Moreover, the presence of higher fat may have caused a decrease in solubilization of starch by lowering mechanical breakdown of the starch granules resulting into decrease in expansion (Moraru and Kokini ).…”

“…RDS of extrudates showed a positive correlation with SME ( r = 0.326, P ≤ 0.05). This might be attributed that when less SME was applied during the extrusion processes, a decrease in degree of gelatinization occurred (Feng and Lee ). ER of extrudates showed a highly positive correlation with SDS and resistant starch ( r = 0.659 and 0.783, respectively, P ≤ 0.005).…”

“…Wang and Ryu () reported that raw materials encounter various physicochemical changes during extrusion, including change in color, gelatinization of starch, and protein denaturation. Feng and Lee () reported that specific mechanical energy is a good indicator of the extrusion conditions as well as certain properties of extrusion products like expansion, solubility, and density.…”

Synergistic Effects of Barley, Oat and Legume Material on Physicochemical and Glycemic Properties of Extruded Cereal Breakfast Products

“…Extrudates usually have a puffy, crispy texture with a sweet flavor (Bisharat et al . ; Feng and Lee ). However, traditional extruded food is considered as a high energy and starch product with low levels of protein, vitamins and minerals (Brennan et al .…”

“…Starch gelatinization occurs in the extrusion processing. Extrudates usually have a puffy, crispy texture with a sweet flavor (Bisharat et al 2013;Feng and Lee 2014). However, traditional extruded food is considered as a high glycemic response by altering food or digesta rheological properties (Londono et al 2015).…”