Optimisation study on sonication conditions and inulin on the modification of Herba rice structure by response surface methodology

The main cause of obesity is overconsumption. The idea of enhancing satiety and satiation is considered an effective way to control appetite and regulate energy and intake of food. The main objective of the study is to make rice healthier for consumption through texture and structure modification of rice grain using optimised ultrasound treatment and inulin incorporation. Sonication is used to alter the microstructure of rice grain by degradation of rice starch to manipulate the water absorption of rice and thus volume expansion during cooking. Greater porosity of rice grains from sonication treatment allows better applications of inulin. Herba rice was sonicated at different amplitudes (0 µm to 60 µm) in an inulin solution of concentration 500 mg/50 mL. The water absorption ratio was calculated, and texture properties (hardness, cohesiveness, gumminess and chewiness) were determined using a texture analyser. The changes in amylose content were determined by using the Megazyme Amylose kit and iodine absorbance spectra. This paper illustrates the effect of inulin on ultrasonic modification of Herba rice physical properties, focusing on dry grain hardness, grain water absorption ability, grain microstructure and cooked texture profile. Response surface methodology, or RSM, is a technique fundamentally accepted as a way to optimise a variety of procedures. Response surface methodology was used to estimate the optimal sonication amplitude. It is proven that sonication is a useful and effective way to modify rice grain texturally and structurally, and to improve inulin absorption in rice, with an amplitude of 30 µm being the optimal for 15 mg inulin absorption and 25% amylose reduction. The combined treatment of sonication and inulin application improved key satiety-related texture properties, such as 20% gain in chewiness and 8% gain in water absorption ratio. Sonication can help achieve better inulin application, and through the presence of inulin in rice, improve its texture properties and swelling behaviour.