Evaluating the Incorporation of Myrtus communis L. Leaves Infusion in Alginate-Based Films and Spheres to Enhance the Oxidative Stability of Oil-in-Water Emulsions.

Myrtus communis L. is a species of the Myrtaceae family that is found in the Mediterranean region, and it is traditionally recognized for its importance and different uses. The objective of this study was to determine the effect of M. communis L. leaf extract (MCLE), which was incorporated directly into alginate spheres and films, on preserving oil-in-water emulsions from oxidation. For this purpose, the solvent extraction (with ethanol at 40, 60, and 80%) of the antioxidant compounds was optimized (total phenolic compounds (TPCs) and total flavonoid content (TFC)) along with the scavenging activity. The best condition for the extraction corresponded with 60% ethanol (MCLE60), with a TPC of ~66.06 g GAE/L and a TFC of ~18.91 g QE/L, which was selected for use in the following assays. MCLE60 showed a considerable radical scavenging activity (24.85 mmol TE/L in FRAP, 28.75 mmol TE/L in DPPH, 30.61 mmol TE/L in ABTS, and 14.94 mmol TE/L in ORAC), which was probably due to its content in the phenolic compounds arbutin (122.08 mg/L), epicatechin (73.89 mg/L), sinapic acid (51.85 mg/L), and gallic acid (36.72 mg/L). The oil-in-water emulsions with the MCLE60 spheres showed the best oxidative stability (TBARS ~2.64 mg MDA/kg of emulsion, PV ~35.7 meq hydroperoxides/kg of emulsion) in comparison to the control. The film was also able to protect the emulsion from oxidation for more than a week at 30 °C (TBARS ~1.9 mg MDA/kg of emulsion). The alginate films with MCLE60 presented an important release of phenolic compounds in water and acetic food simulants, while in both ethanol simulants, the release of TPC remained more stable over time. Thus, this study highlights the potential uses of MCLE as a natural ingredient for emulsion oxidative preservation and the production of alginate delivery systems (spheres and films).

Antioxidant and Antiradical Activities of Hibiscus sabdariffa L. Extracts Encapsulated in Calcium Alginate Spheres.

The interest in natural sources with high antioxidant powder has recently increased in several sectors. Ionic gelation methods could be used to protect bioactive substances to control the kinetics and release of these ingredients to the food matrix. This study dealt with the evaluation of the antioxidant capacity and scavenging activity of extracts of Hibiscus Sabdariffa L. (HSL) (with 50% ethanol) encapsulated in calcium alginate spheres as a new source for preserving food against oxidative damage. Their antioxidant activity was measured in different o/w emulsions in which HSL spheres reduced the formation of hydroperoxides (~80%) and thiobarbituric-acid-reactive substance products (~20%). The scavenging activity of HSL extracts was measured in different food simulants (water, water acidified with 3% acetic acid, ethanol at 50%, and pure ethanol), and corresponded to 0.20-0.43, 0.31-0.62, and 11.13-23.82 mmol Trolox/mL extract for Trolox equivalent antioxidant capacity (TEAC), 2,2-diphenylpicrylhydrazyl (DPPH), and oxygen radical absorbance capacity (ORAC) assays, respectively. In general, the best antiradical activity was observed in the ethanolic and acidified mediums, in which the highest concentration of released polyphenols ranged from 0.068 to 0.079 mg GAE/mL. This work indicates the potential of alginate spheres for encapsulating antioxidant compounds as an innovative strategy for several industrial applications.