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This research evaluated the influence of natural emulsifier on the emulsion particle size of the black pepper oleoresin combined with a sucrose solution, and its effects on the kinetics of chayote osmodehydration and the extent of piperine fortification. Macroemulsions with gum arabic (GA) and nanoemulsions with whey protein concentrate (WPC) were prepared in a 50% sucrose solution. The mean particle size and polydispersity index of both sucrose-emulsion solutions were determined using dynamic light scattering, and the kinetics of water loss (), solids gain (), water activity (), and water diffusion coefficients () were obtained during the osmotic processing (25 - 45 °C). With a particle size of 165 nm, the WPC nanoemulsion had a higher viscosity than the GA emulsion, which measured 655 nm making them susceptible to coalescence. Scanning electron micrographs revealed that during osmotic dehydration, the WPC nanoemulsions formed dense layers within the chayote tissue. This resulted in reduced water loss kinetics and diffusivity, particularly at high temperatures. In terms of fortifying chayote with piperine, the use of a macroemulsion resulted in greater rates of impregnation (0.12 mg piperine (g wet solids min)-1) compared to the nanoemulsion, which had rates of 0.04 mg piperine (g wet solids min)-1. After 420 minutes of osmodehydration, it was observed that the GA macroemulsion resulted in higher levels of piperine impregnation than the WPC nanoemulsion. These findings have important implications for successfully fortifying fruits and vegetables with lipophilic bioactive compounds using emulsions in combination with the osmotic dehydration technique.