Development of barnyard millet flour rich in bioactive compounds with enhanced functional properties by application of multipin atmospheric cold plasma

Abstract

Cold plasma, a nonthermal technology, aids in modifying food materials with the least thermal damage and negligible rise in temperature. This research explains the implications of multipin atmospheric cold plasma (MACP) treatment on barnyard millet flour (BMF), focusing on its functional properties and bioactive compounds, such as total phenols and flavonoids, along with antinutrients, as well as its physicochemical properties, including color, pH, moisture content, proximate composition, and morphological alterations. Dehulled and ground barnyard millet was treated with MACP at different power levels (10–30 kV) for 10–30 min. The higher voltage–time treatments (30 kV:20 min and 30 kV:30 min) were found significantly affecting the samples compared to the control. Specifically, the 30 kV:30 min treatment showed a prominent increase in water solubility index (0.83–3.92 g/g), water absorption capacity (1.08–1.59 g/g), viscosity (164.31–180.14 centipoise), oil absorption (1.94–2.35 g/g), emulsifying (37.40%–44.51%), and foaming capacity (20.61%–24.99%), along with the bioactive compounds such as phenol content (229.33–280.54 mg gallic acid equivalents/100 g) and flavonoid content (173.75–244.71 mg quercetin equivalents/100 g). Furthermore, Fourier transform infrared spectrometry analysis revealed shifts in functional groups, X-ray diffraction analysis demonstrated changes in crystallinity, and scanning electron microscopy imaging depicted morphological alterations post-MACP treatment. The antinutrient factors, phytic and tannic acid, decreased significantly (p < .05), with the most prominent decrease at 30 kV:20 min for the latter. The 30 kV:30 min treated flour, in particular, demonstrated significant improvements in BMF properties, and MACP can be further employed for better solubility and dispersibility of powdered food products, offering versatile applications in baked, functional, and gluten-free products.

Practical applications

Barnyard millet, a naturally gluten-free grain rich in protein and fiber, upon the multipin atmospheric cold plasma treatment, offers opportunities in a wide range of practical applications due to the increased functional properties, including water solubility, water absorption, oil binding capacity, foaming–emulsifying abilities, and viscosity. Additionally, the enhanced properties allow for the development of better extruded products, including nutritious breakfast cereals and healthy snacks with improved texture and stability, while promoting the utilization of underutilized grains like barnyard millet.