Cold plasma treatment as an intervention strategy to achieve safety in pearl millet flour

Abstract Pearl millet flour (PMF) is known as a nutri-cereal due to its rich nutritional profile, with essential amino acids and omega-3 fatty acids. However, PMF is contaminated with pathogens due to unhygienic postharvest practices. This study aims to inactivate Salmonella spp. inoculated in grain or flour using sequential combinations of cold plasma treatment of grain (treatment A: 20−28 kV/20−60 min), tempering of grains with plasma-activated water (PW) (treatment B: PW prepared by exposing water at 20−28 kV/20−60 min), and cold plasma exposure of PMF (treatment C: 20−28 kV/20−60 min). Individual cold plasma treatment of the grains (treatment A) and the combination of A + C achieved the greater reduction of 1.4 and 2.6 (lg (CFU/g)) at 28 kV/60 min, respectively. With the combination treatment of A + B + C, including cold plasma treatment of the grain, followed by tempering with PW and cold plasma treatment of the flour at 28 kV/60 min, the highest reduction of 3.0 log cycles was achieved. Except for condition A + B + C, cold plasma treatment at all conditions did not affect the bulk, true, tapped density, geometric mean diameter, protein, or ash content of the PMF, but it reduced the moisture content of the flour. The A + B + C treatment led to a lower true, bulk, and tapped density, an increase in geometric mean diameter, and changes in the color profile. A + B + C achieves 3.0 log reduction with slight modification of the physicochemical properties, but further optimization is required to improve the efficiency of the process.