Investigating Thermal Process-Induced Functional Changes in Little Millet: A RSM-based Comparative Insight

Department of Food Technology, Guru Nanak Institute of Technology, Kolkata, West Bengal 700110, India

Abstract

Little millet is emerging as a potential alternative staple crop with gluten-free characteristics and growing demand for health-oriented food formulations. However, the effects of contemporary thermal processing on the functional properties of little millet have yet to be fully explored. The present study investigated the effect of microwave and induction heating treatment on the key functionalities, such as water solubility index (WSI), water absorption capacity (WAC), and oil absorption capacity (OAC) of ground little millet flour, which were measured using a full factorial and response surface methodology (RSM) of little millet flour. The microwave and induction temperatures varied between 110–170°C and 120–160°C, respectively, with a time variation from 2–8 min. Due to the little millet flour exhibiting minimal thermal solubility, the WSI, which remained low and constant, showed little response to the processing treatments (0.10–0.17). However, process intensity did positively correlate with WAC, which reached values of 7.68 g/g and 6.77 g/g for induction and microwave treatments, respectively, clearly indicating increased water absorption and WAC due to starch gelatinization and the structural unfolding of the associated proteins. Further, OAC was examined with mustard and sunflower oil, and there is a clear positive correlation evident for OAC with oil type and process. Induction heat processing for mustard oil produced the most significant OAC values (0.27–7.82 g/g), while microwave processing with sunflower oil exhibited lower values (0.30–2.83 g/g). In conclusion, the study showed that the application of induction and microwave processing technologies can be employed for tailored processing to achieve the desired functional and processing attributes for little millet flour.