Consumers are increasingly demanding foods with lower synthetic preservatives. Plant essential oils are natural compounds with remarkable antimicrobial properties and may be incorporated as emulsions into water-soluble polymers to form antimicrobial films. Coarse emulsions (diameters of 1.3-1.9 μm) and nanoemulsions (diameters of 180-250 nm) of clove bud (Syzygium aromaticum) and oregano (Origanum vulgare) essential oils were produced through low-speed mixing and ultrasonication, respectively. Methylcellulose was added for film-forming purposes. Both essential oils reduced the rigidity and increased the extensibility of the methylcellulose films, effects that were even more pronounced for nanodroplets. Both essential oils lessened the counts of yeasts and molds in sliced bread during 15 days, and droplet size reduction provided a further improvement in antimicrobial properties. Due to increased bioavailability, less preservative content might be used and still deliver the same antimicrobial efficiency if encapsulated in smaller particles.