Stability of whey protein isolate–chitosan Pickering emulsions and their application in mayonnaise

The long-term stability of Pickering emulsions is crucial for their application in food systems. This study aimed to evaluate the stability degradation of oil-in-water (O/W) Pickering emulsions stabilized by whey protein isolate (WPI) and chitosan (CS), and to assess their applicability in reduced-fat mayonnaise formulations. Optical tweezers were employed to quantify the interaction forces between emulsion droplets during storage, in combination with microstructural observation and ζ-potential analysis. It was found that the O/W emulsion prepared with a 50% aqueous phase volume fraction maintained a stable droplet size over the storage period without significant changes. The ζ-potential decreased from 79.16 mV to 53.62 mV, while the maximum droplet contact force gradually decreased from 69 pN to 37 pN by day 45. By day 60, droplet coalescence was observed. Compared with traditional rice bran oil mayonnaise, the mayonnaise formulated using this Pickering emulsion exhibited superior mechanical stability and resistance to destabilization. In particular, the formulation with a Pickering emulsion-to-egg yolk volume ratio of 4:1 showed the best mechanical performance, with the droplet contact force gradually decreasing from 68 pN on day 0 to 62 pN on day 20. This study provides a rapid method for evaluating the stability of food systems, offering potential applications in the food industry.