Artubuts unedo L. leaves extract as a potential ingredient for the production of active-films and the preservation of oil-in-water (O/W) emulsions from oxidation

Natural antioxidants are of great interest to the food industry to prevent food from oxidation. In line with this trend, this study aimed to investigate the potential application of Arbutus unedo L. leaf extracts (AULE) for active-film production and preserving O/W emulsions against oxidation. The best-extracting conditions for the phenolic compounds and flavonoids were obtained with an ethanol:water solution at a 60:40 ratio (AULE60)(∼73.28 mg Gallic Acid Equivalents/100 mL and ∼27.01 mg Quercetin Equivalents/100 mL, respectively), which was characterized by arbutin, epicatechin, gallic acid and ferulic acid, and exhibited radical scavenging activity. Different alginate-films were also produced. Glycerol decreased their strength and increased their plasticizing behavior, whereas the calcium-crosslinking solution increased their rigidness. The addition of AULE60 resulted in brittle films. The immersion of these films in several food simulants showed that water and acid exhibited the highest values of released polyphenols and radical scavenging activity, in comparison to the ethanolic (20 or 50%) simulants. It was finally demonstrated that O/W emulsions with AULE60 (5 or 10%) or with the AULE60-alginate film exhibited the best oxidative stability over time. Therefore, the potential use of AULE as a natural ingredient for these applications was demonstrated. • Different ethanolic Arbutus unedo L. leaves extracts (AULE) were obtained. • The arbutin, epicatechin and gallic acid were the main polyphenols of the AULE. • Films with AULE resulted less porous and more brittle. • AULE alginate-films exhibited the highest release at water and acetic simulants. • The AULE (films and extracts) improved the oxidative stability of O/W emulsions.