Atmospheric cold plasma treated raw bovine colostrum: Protein structure, lipid oxidation, physicochemical properties, and Escherichia coli population

Bovine colostrum (BC), valued for its nutrient density and bioactive compounds, demands preservation techniques that retain these beneficial properties, driving interest in non-thermal approaches such as atmospheric cold plasma (ACP). This study assesses ACP’s impact on the physicochemical, microbiological, and structural properties of raw BC using a continuous-flow dielectric barrier discharge (DBD) reactor at 30 kV and 3.5 kHz for 15 and 30 minutes, within 20–25°C. Optical emission spectroscopy (OES) identified a predominance of reactive nitrogen species (RNS) within the plasma discharge. ACP treatment achieved a 60% reduction in Escherichia coli populations after 30 minutes ( p < 0.05). Analysis of lipid hydroperoxides (A 500 ≈ 0.043), total protein content (≈ 69.1%), lactose levels (≈ 1.7%), chromaticity indices (a* ≈ -4.18, b* ≈ 18.87), browning index (A 420 ≈ 0.012), and viscosity (≈ 0.55 Pa·s at a shear rate of 0.1 s -1 ) showed no statistically significant alterations ( p > 0.05), indicating minimal oxidative or rheological impact, though a significant decrease in lightness (L*, p < 0.05), suggested a slight darkening. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) confirmed stable profiles of proteins in BC after ACP treatment, including immunoglobulin G, β-lactoglobulin, α-lactalbumin, lysozyme, lactotransferrin, and bovine serum albumin, whereas circular dichroism (CD) spectroscopy detected significant secondary structural shifts, characterized by increased α-helix, parallel β-sheet, and turn conformations, alongside reductions in antiparallel β-sheet content and the emergence of distinct conformational domains. These findings affirm ACP as an effective non-thermal alternative, underscoring its potential to enhance BC preservation through microbial control and the retention of key proteins, while revealing secondary structural modifications that require further exploration of their functional impact on BC.