Impact of non‐thermal plasma generated using air and nitrogen on functional properties of milk protein dispersions

Abstract

AbstractThis study focuses on improving the functionalities of milk protein concentrate (MPC) using a nonthermal plasma jet and plasma‐activated water (PAW) with atmospheric air and nitrogen as source gases. The 5% and 10% MPC dispersions were directly treated with a plasma jet, and PAW was used to make the MPC dispersions. The dispersions were analyzed for changes in protein structure and functional properties. The treatment altered the secondary structure of MPC protein structure by increasing β‐components and changing the order of random coils. The solubility of the PAW‐treated 5% protein dispersions doubled due to plasma‐induced modification of hydrophilic and covalent bonds of the protein, but this increase was not significant for the 10% dispersions due to less hydration. Emulsifying capacity increases by around 7% for plasma jet and PAW with air, owing to hydrophobicity on the particle surface. The gelation capacity and heat coagulation time rise by almost twice; however, foaming capacity decreases, indicating protein structural modifications and aggregations caused by plasma exposure. The viscosity of the 5% dispersions decreased due to high solubility, while that of the 10% dispersions increased due to less hydration. Principle component analysis was used to correlate the change in functionality with different operating parameters. In conclusion, this study illustrates that the functional properties of MPC can be significantly modified through plasma treatment. The observed changes depend on several factors, including the mode of plasma exposure, the source gas used to generate the plasma, and the concentration of the protein solution.Practical applicationsMilk protein concentrate (MPC) is a promising ingredient in food products such as cheese, cultured dairy items, nutritional goods, infant milk formulas, ice cream, dairy‐based drinks, sports beverages, and a variety of health‐focused products. However, the application is profoundly hindered due to its poor solubility and solubility‐related functional properties. MPC powders lose functionalities during manufacturing and gradually lose them again during processing and storage. This study explores the potential of non‐thermal plasma to improve the functional properties of proteins. This study explores the potential of two different discharges: plasma jet and plasma‐activated water (PAW), using atmospheric air and nitrogen as source gases. The findings of this study would also help to understand the types of plasma discharge (jet vs PAW) and types of sources of gases that can be used in industrial applications. Some optimization parameters of this study can be used for scaling up the plasma processing of milk or dairy products. In addition, PAW is being very well studied to improve food safety, and this study would provide information on the physicochemical properties of MPC. Therefore, it would also help to understand how to apply non‐thermal plasma to achieve both microbial and physical effects.