Effect of internal and external gelation on the physical properties, water distribution, and lycopene encapsulation properties of alginate-based emulsion gels

It is challenging to incorporate lycopene, a strongly hydrophobic nutraceutical, into functional foods because of its low water-solubility and poor bioaccessibility. In this study, we therefore examined the potential of alginate-based emulsion gels to encapsulate and deliver lycopene. Alginate can be gelled using either internal or external gelation mechanisms, but few studies have compared the advantages and disadvantages of these two approaches for producing emulsion gels. For this reason, we compared the structure, water distribution, water mobility, and simulated digestion of lycopene-loaded emulsion gels formed by gelling alginate within the aqueous phase using either the internal or external methods. The internal gelation method produced emulsion gels that contained smaller oil droplets, and had a higher hardness, water holding capacity, and freeze-thaw stability. Moreover, the internal gelation method led to emulsion gels that had a slightly higher lycopene bioaccessibility (36.1%) than the ones formed by the external gelation method (33.4%). These findings are important for optimizing the design and fabrication of emulsion gels suitable as delivery systems for nutraceuticals in the food industry.