Interaction between soy protein isolate and surfactant at the interface of antibacterial nanoemulsions loaded with riboflavin tetra butyrate

Abstract

SummaryRiboflavin tetra butyrate (RTB) is an effective antimicrobial photosensitiser that poses a challenge for long‐term preservation and application due to its hydrophobicity and instability. To overcome this problem, a series of nanoemulsions loaded with photosensitiser RTB was prepared in this study by using soy protein isolate (SPI) as an emulsifier and small molecule surfactant (X) as co‐emulsifier. The interaction mechanism of SPI+X co‐emulsifier and its influence on the stability of emulsion and photosensitiser were explored, and the photodynamic bactericidal effect of the prepared RTB emulsion on S. aureus was studied. SPI and four types of surfactants were present in the form of synergistic (Tween 80, T80) or competition (Span 80, S80 and lecithin, LEC) adsorption or formation of Pickering emulsion (Sodium dodecyl sulphate, SDS) at the oil–water interface. The experimental results revealed that the stable encapsulation ability of RTB emulsions for photosensitisers and their preservation ability can be drastically improved. This work verified that all RTB emulsions could inactive S. aureus under blue light, with an antibacterial ratio of more than 70%. Therefore, the emulsion‐based delivery system effectively improved the water dispersibility and chemical stability of RTB. These results demonstrate that RTB emulsion has the potential to be used as a food‐grade antibacterial emulsion.