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An experimental study on rheological behaviors of rice based products in an in-vitro simulated digestion system
The gastro-intestinal behaviors of foods influence their physiological functions in the human body. In-vitro methods simulating digestion processes have been extensively used to study the gastro-intestinal behaviors of foods due to more rapid and less expensive advantages. However, there is a lack of systematic studies to monitor the rheological changes of the food digesta in real time. In this study, rice-based products (specifically, extruded noodles) were prepared with three varieties of rice flours with different contents of amylose and their physicochemical properties and in-vitro digestibility were then characterized from a rheological point of view. The rice flours with higher amylose contents exhibited greater stability to dual mixing and higher degrees of starch gelatinization and retrogradation in thermo-mechanical measurements. In addition, greater elastic properties were clearly observed in the high amylose rice samples. The noodles which were produced with high amylose rice flour had a harder texture and reduced cooking loss. When the rheological changes of the extruded rice noodles were monitored in real time during the in-vitro starch digestion, the rice noodle digesta with higher amylose content exhibited greater viscosities throughout the simulated oral-gastric-intestinal digestion steps. The flow behavior of the rice noodle digesta consisted of the Power-law region and infinite shear plateau that were satisfactorily characterized by the Sisko model (R2>0.99). Hence, this study was conducted to investigate the physicochemical and in-vitro digestibility of extruded rice noodles with different amylose contents. These results can provide a promising opportunity for the food industry to research in-vitro digestion and physicochemical characteristics of rice-based products.
