Microwave Assisted Fluidized Bed Spray Soaking and Gelatinization for Whole Grain Rice Fortification

Abstract

Extruded fortified rice kernel often differs in its physicochemical, soaking, and cooking properties from regular rice and is not preferred due to alterations in its sensory properties. Fortified rice with identical physicochemical and sensory properties as regular rice is thus needed, and this study aimed to do so. Whole-grain rice having 55% degree of gelatinization (DG) was simultaneously soaked with iron salt (NaFeEDTA) solution and dried in a microwave-assisted-fluidized bed spray-soaking and drying (MAFBSD) setup that facilitated iron migration, further gelatinization (60%), drying of rice kernel, and develop identical gelatinization induced whole grain fortified rice kernel (GIWGFRK). The impact of the MAFBSD processing conditions, that is, spray-flow rate, microwave power density during soaking, and drying of rice at fixed fluidization velocity (12 m/s) on rice quality was initially explored, and optimized conditions were then used for rice fortification. Up to 32% of additional moisture gain through microwave-assisted soaking (at 50 mL/min spray-flow rate for 2 h) followed by microwave drying (for 85 min at 0.6 kW/kg) to 13 ± 1% moisture content did not show any visible fissure and alteration in head rice yield. Spray soaking of NaFeEDTA solution (0.106 mg/mL) with the pre-optimized processing condition resulted in a gain in iron content (21.25 mg of iron/kg), nonsignificantly impacting its quality. After washing and cooking, the fortified rice showed 52.19 ± 2.46% and 22.77 ± 3.19% iron retention, respectively. Further modification in gelatinization parameters may offer more nutrients retention, additionally gelatinization-induced fortification as a practical approach for whole-rice fortification. This research enables the commercial production of fortified rice with identical sensory and physicochemical properties to regular rice, improving consumer acceptance and addressing iron deficiency without compromising rice quality.