Incorporation of antimicrobial nanoemulsions into complex foods: A case study in an apple juice-based beverage
Anna Molet-Rodríguez, AnaTurmo-Ibarz, Laura Salvia-Trujillo, Olga Martín-Belloso
Department of Food Technology, University of Lleida – Agrotecnio Center, Av. Alcalde Rovira Roure 191, 25198, Lleida, Spain.
Despite the proven antioxidant and antimicrobial efficiency of nanoemulsions as carriers of essential oils, there is scarce research on their behavior once incorporated into complex food matrices. In the current work, lemongrass or mandarin essential oil (LEO or MEO) nanoemulsions were formulated using three different continuous phases (water, an apple juice model and an apple juice-based beverage). Droplet size, ζ-potential, colloidal stability as well as the antioxidant and antimicrobial activity were studied. The increase in the complexity of the continuous phase promoted the formation of nanoemulsions with smaller sizes. Consequently, creaming phenomena was prevented in complex systems. Moreover, nanoemulsions formulated using the apple juice-based beverage presented a high antioxidant activity, with values of up to 400 mg Eq. Trolox/mL, probably due to the presence of polyphenols. Nevertheless, nanoemulsions presented slower and lower inactivation kinetics at increasing complexity of the continuous phase, which may be related to the ability of sugars to protect cell damage. This work evidenced that antimicrobial nanoemulsions within complex food matrices leads to higher colloidal stability and antioxidant activity, but lower bactericidal activity than nanoemulsions alone. Hence, it provides valuable information for the design of complex foods with nanoemulsions as delivery systems of functional ingredients.
Keywords: Nanoemulsions, Essential oils, Colloidal stability, Antimicrobial activity, Apple juice.