Effect of cold plasma treatment on the structure and emulsifying activities of phycocyanin

Abstract

Modifying natural active proteins through non-thermal processing techniques to obtain their functional diversity is an interesting and challenging aspect in the food industry. In this study, cold plasma was employed as a sustainable and efficient processing technique for phycocyanin (PC) modification. The cold plasma treatment improved the foaming property of PC. Moreover, subjecting PC to cold plasma treatment at 50 W for 20–60 s significantly reduced the oil-water interfacial tension. Conversely, plasma treatment reduced the elasticity of the PC interfacial layer and diminished the interactions between the proteins in that layer. Simultaneously, the particle size of PC increased while its secondary structure transitioned from alpha-helix to random coil after cold plasma treatment. SEM analysis revealed an augmented aggregation tendency among PC with extended cold plasma treatment duration. Additionally, a plasma-modified PC (50 W, 20 s) was utilized to develop an emulsion incorporating thyme essential oil and coconut oil, which displayed a more compact and porous microstructure and demonstrated antimicrobial activity against E. coli. This study proposes a simple and effective method for PC modification, and demonstrates that the functional properties of PC can be effectively enhanced by utilizing cold plasma technology at the appropriate processing time, thus providing a foundation for the application of PC and cold plasma technology in the field of food.