Reimagining space foods: Generation of O/W nanoemulsions via spontaneous emulsification in self-assembly, macrofluidics, and microfluidics to produce fortified beverages for astronauts

Abstract. Ensuring palatable, nutritionally balanced food options for long-term space missions remains a challenge. Our lab explores the concept of using fortified nanoemulsified beverages tailored to individual astronaut needs to improve life and well-being during space missions. Combining a self-assembly emulsification (solvent-free version of the spontaneous emulsification) with a continuous, microfluidic process has been demonstrated before to allow a resource-efficient production of beverage nanoemulsions. This study compares five different process setups (self-assembly only; self-assembly and batch process in small- and medium-scale; self-assembly and continuous process in single- and multi-contact) in regard to average droplet diameter of formed emulsions at constant surfactant concentration. Forced convection significantly decreases average droplet diameter in all cases, yet, the microfluidic continuous processes achieve the smallest average droplet size at 62-109 nm. Results indicated further that synthetic surfactant concentrations can be reduced by decreasing overall oil content, likely due to increased mass transfer of the surfactant between phases. This methodology not only supports astronaut nutrition but also provides a scalable framework for resource-efficient nanoemulsion-based production across the food, cosmetic, and pharmaceutical industries.