Allicin is one of the main bioactive organosulfur compounds synthesized in Allium species. It exhibits antioxidant and immunomodulatory properties, which can be used to prevent several diseases, including diabetes and cardiovascular. However, allicin is unstable and susceptible to oxidation, which limits its therapeutic potential. Therefore, nanoencapsulation can be employed to protect and prolong its biological activity. Among the available methods, anti-solvent precipitation has garnered increasing attention due to its simplicity and scalability. Thus, the objective of this study was to develop gelatin-allicin nanocapsules using the anti-solvent precipitation method. Fish gelatin was dissolved in water, followed by the incorporation of an allicin-rich extract. Ethanol was then added as the anti-solvent, resulting in final ethanol concentrations of 15, 30, 35, 40, 45, 50, 55 and 60% (m v^-1). The process was characterized by turbidity measurements using a turbidimeter, zeta potential determination through electrophoretic light scattering (ELS) and particle size analysis via dynamic light scattering, (DLS). The results showed a decrease in zeta potential as ethanol concentration increased, ranging from 1.2 mV to 0.6 mV. Moreover, the increase in ethanol concentration to 50% led to an enhancement in particle size (345-851 nm). This effect could be attributed to conformational changes in the gelatin structure, leading to tighter packing with allicin. Furthermore, the reduction in repulsive electrostatic interactions could have promoted greater hydrophobic interactions between the gelatin-allicin particles. The turbidity results demonstrated that ethanol concentrations of 15-30% produced thermodynamically stable solutions (26-59 NTU), while 35-50% ethanol led to a metastable region with nanocapsules formation (147-360 NTU). At 55% ethanol, the system entered a thermodynamically unstable region (817 NTU), resulting in phase separation. Therefore, this study investigated the effect of ethanol as an anti-solvent in the formation of gelatin-allicin nanocapsules, which have potential applications as a food supplement or functional food ingredient.