Novel thermal and non-thermal millet processing technologies: advances and research trends

Global agriculture and food security are greatly impacted by climate change, water resource depletion, and a rising population. Cereals such as rice, wheat, maize, barley, oats, and rye account for the vast majority of food consumed worldwide. The requirement to shift from the current grain staples is necessitated by the significant water needs of above crops. Millets have the potential to strengthen food security due to their high nutritive quality, drought resistance, adaptability to local growing conditions, resistance to pests and diseases, and resilience to environmental shocks. Despite the benefits, the utilization of millets is constrained due to the poor shelf life of the flour caused by the activity of enzymes such as lipase, lipoxygenase, peroxidases, and polyphenol oxidase. Numerous food processing techniques have been explored in an effort to stabilize millet products while maintaining their nutritive characteristics. Microwave, radiofrequency, infrared, ohmic heating, as well as non-thermal methods like pulsed electric field, cold plasma, irradiation, high-pressure processing, ozonation, and ultrasound treatment, have drawn the most attention among these technologies due to their short processing time, minimal nutrient loss, and lower energy consumption. The work reviews recent developments in thermal and non-thermal millet processing technologies. It also discusses challenges, bottlenecks, and perspectives for further research.