Effect of dielectric barrier discharge plasma on background microflora and physicochemical properties of tiger nut milk

The microbial and physicochemical properties of tiger nut milk were studied under different dielectric barrier discharge (DBD) plasma exposure time: 2, 4, 6, 8, and 12 min. Following the plasma treatment, a significant reduction in the microflora was observed at 2, 4, 6 and 8 min treatment time with 12 min reaching the un-detectable limit. The treatment did not result in any significant change in soluble solids and fat contents. Significant reduction in pH was recorded after 8 and 12 min treatment, whereas heightened titratable acidity and lipid oxidation were noticed in all the treated samples. The protein content decreased significantly in all the treated samples, while peroxidase activity only decreased when the treatment time was extended beyond 4 min. The loss in enzyme activity was due to the oxidation effect plasma reactive species including atomic oxygen, ozone, and hydroxyl radicals, which might have oxidized the amino acid side chain. The findings presented here could be a prelude for the potential application of DBD plasma treatment of tiger nut milk in the food industry.