Evaluating the Effectiveness of Extrusion in Fortifying Rice Analogues With Dietary Fiber

The present work was undertaken to evaluate the effect of extrusion processing parameters on the incorporation and retention of dietary fiber (DF), mainly cellulose and hemicellulose, in fortified rice analogue. Specifically, the study focused on fortifying the rice with soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) in a 1:3 ratio. The process parameters such as moisture content (20%-30%), screw speed (120-160 rpm), and die temperature (90-110°C) were used as independent parameters, whereas physicochemical,  functional properties, SDF and IDF content were used as dependent parameters through response surface methodology. The fortified rice kernel (FRK) showing maximum retention of SDF and IDF was optimized and analyzed for physical, textural, rheological, invitro starch digestibility, structural and morphological properties. Extrusion significantly influenced the physicochemical, functional, rheological, and physical properties. The optimized FRK at 90°C/120 rpm/20% moisture content showed SDF 0.042 g/g and IDF 0.08 g/g content with a hardness of 64.96 N. The in vitro starch digestibility revealed an increase in resistant starch content from 12.42% to 16.50% in FRK. This enhancement can be attributed to the structural modifications induced by extrusion, which promotes starch retrogradation, and the addition of fortified DF. Overall, extrusion parameters have significantly influenced the fortification of SDF and IDF. PRACTICAL APPLICATIONS: Rice is a staple food consumed across the globe, and its low nutritional value contributes to nutritional deficiencies and the risk of chronic diseases such as cardiovascular diseases. Fortification is an effective method of alleviating the causes of nutritional deficiencies. Among the fortification methods, extrusion is a cost-effective and efficient technology for fortification of macronutrients. This study exemplified that extrusion processing can efficiently fortify broken rice with dietary fiber by achieving a 1:3 ratio of soluble dietary fiber to insoluble dietary fiber. The optimized extrusion parameters temperature, screw speed, and moisture content showed enhanced nutritional, digestibility, textural, pasting, and functional properties of the fortified rice kernels. The results of this study evidenced extrusion as an effective tool for the development of fiber-fortified rice. Additionally, the use of broken rice, an underutilized by-product of rice milling, underscores the sustainability of this fortification strategy, offering a value-added pathway for its conversion into functional food ingredients.