Retention and Antimicrobial Activity of Alginate-Encapsulated Bioactive Compounds from Leaves and Fruits of Myrtle (Myrtus communis L.)

Myrtle (Myrtus communis L.) is a rich source of bioactive compounds and nutraceuticals of different polarities obtained from different parts of the plant, whose synergistic effect could be harnessed through the formulation of capsules. The aim of this work was to investigate the antimicrobial activity of three myrtle formulations: essential oil and aqueous leaf extract and supercritical fruit extract, as well as the retention of volatile, phenolic and lipid compounds in low-viscosity alginate capsules obtained by the electrostatic extrusion microencapsulation of these formulations combined. At a temperature of 48 °C, 1.27% emulsifier and 3% CaCl2, 72.86% of the volatiles, 61.13% of the phenolics and 62.80% of the lipids were retained. All tested extracts showed good antibacterial activity, especially against Staphylococcus aureus and Listeria monocytogenes, which were the most sensitive. An exceptionally high inhibitory effect was achieved by aqueous leaf extract against L. monocytogenes (35.25 mm) and essential oil against Escherichia coli (28 mm). Supercritical extract and essential oil showed good antifungal activity, and none of the extracts showed inhibitory activity against lactic acid bacteria.