Atmospheric Cold Plasma Treatment of Whey: Insights Into Microbiological Quality and Structural Characteristics of Whey Proteins

Whey is the byproduct of manufacturing cheese, paneer, etc. It contains nearly 50% of solids originally present in milk and is valued for its nutritional and functional qualities. However, whey has a relatively short shelf life of just 1–2 days even when refrigerated, which prevents its direct utilization by consumers in various ways. In this study, atmospheric cold plasma was used as a nonthermal treatment to destroy pathogenic microorganisms and extend the shelf life of whey. After treatment, the microbiological and physicochemical qualities and structural changes in whey proteins were analyzed. About 2.6 log colony forming units (log CFU)/mL reduction in total plate count was possible. From UV-Vis, Fourier transform infrared spectroscopy (FTIR), and circular dichroism (CD) spectroscopy results, it was concluded that the secondary structure of whey proteins was altered after cold plasma treatment.