Stabilization of nanoemulsions using cold-water fish gelatin and whey protein isolates/fibrils

Whey protein fibrils (WPF) have attracted increasing attention due to their superior functionality in various applications, including emulsification. However, achieving stable nanoemulsions across different pH conditions remains a challenge. This study aimed to explore the emulsifying properties of WPF combined with cold-water fish gelatin (CFG) across different pH levels and compare them to whey protein isolates (WPI) as emulsifiers for oil-in-water nanoemulsions. Creaming stability results showed that CFG-WPI/WPF emulsions were stable at pH 3, 9, and 11, producing nanosized droplets. However, at pH 5 and 7, emulsions exhibited aggregation and larger droplet sizes, indicating instability. To enhance stability at neutral pH, various protein ratios and higher concentrations were tested. Increasing the protein concentration improved CFG-WPI stability, but CFG-WPF emulsions showed rapid creaming and bimodal droplet distributions. Adjusting the ratio of CFG to whey proteins revealed that CFG-WPI emulsions were most stable at 4:1 and 1:1 ratios, while CFG-WPF emulsions showed pronounced aggregation at 1:1 ratio. Increasing the CFG to WPF ratio improved stability. The findings in this study could offer valuable insights for developing stable protein-based nanoemulsion systems for food and pharmaceutical applications.