Microencapsulation and antimicrobial activity of extract acetone-methanol of Hibiscus sabdariffa L. using a blend modified starch and pectin as a wall material

The objective of this study was to evaluate the antimicrobial effect in vitro of an acetonic-methanol extract (1:1 v/v) from Hibiscus sabdariffa L. encapsulated calyxes using a mixture of modified corn starch (MCS) and pectin as a wall material. Previously, the MCS was hydrolyzed-succinated and processed into a single-screw extruder. For H. sabdariffa extract encapsulation, optimal drying conditions were established using encapsulation efficiency (EE) and antimicrobial activity against Salmonella typhimurium and Staphyloccocus aureus as response variables. Optimum drying conditions were total soluble solids concentration of 10 % (MCS 9% / Pectin 1%) at drying temperature of 120 °C with a maximum EE of 98.5 %. H. sabdariffa extract obtained from solvent blend produced macromolecules extraction that favor the synergism for antimicrobial activity against S. typhimurium and S. aureus with inhibition halos of 19.9 and 20.9 mm, only in extract. While the microencapsuled extract exhibited inhibition halos of 16.8 and 19.9 mm, respectively. The microencapsulates with higher pectin content significantly increased its antimicrobial activity (p ≤ 0.05) as compare to those encapsulates with lower pectin concentrations. This process is due to synergistic reorganizations of the molecular formations of both polymers and the extract leading to a diffusion of antimicrobial compounds. The microcapsules of the acetonic-metabolic extract of Hibiscus sabdariffa obtained in this work are a naturally sourced alternative for the conservation of food products.