Production of Nanocapsules Using Salvia Leriifolia Leaf Extract and Assessing Effects of the Extract and Nanocapsules Containing the Extract on Microbial Properties in Sausages During the Shelf Life

Researches have shown that converting bioactive compounds to nanoscales increases their effectiveness due to their size surface area. Therefore, use of antimicrobial compounds at nanoscales can progress their effectiveness, decreasing their necessary concentrations. Salvia leriifolia, with valuable secondary metabolites such as flavonoids and alkaloids, includes a high antimicrobial activity against a wide range of microorganisms. In the present study, possibility of producing nanocapsules containing leaf extract of S. leriifolia and antimicrobial effects of the extract and nanocapsules containing the extract on sausage samples were investigated.

Emulsion method was used for the preparation of calcium alginate nanocapsules containing the extract. The ratio of extract (at a concentration of 500 mg/ml) to sodium alginate was 1:4. Nanocapsules containing extract was produced by adding calcium chloride nanoparticles to alginate nanoparticles containing extract in three ratios of 1:6, 1:9 and 1:12 within 3, 4 and 5 h. To investigate antimicrobial potency of the extract and nanocapsules containing extract, microbial properties of sausage samples were assessed during two months of storage.

Encapsulation efficiency and zeta potential were high in all samples. Based on the particle size and dispersion index, nanocapsules with an alginate to calcium chloride ratio of 6 to 1 and formation time of 4 h were selected as the best treatment. Results of microbial analysis showed that only in the sample with no preservatives on day 60 of storage, the total microbial count exceeded the national standard limit. After 2 months of storage, the lowest number of molds and yeasts was achieved in sausage samples with nanocapsules containing the extract. None of the sausage samples were contaminated with Escherichia coli, Salmonella, coagulase-positive staphylococci and Clostridium perfringens during the shelf life; however, addition of the extract, nanocapsules containing the extract or nitrite did not prevent growth of the coliforms.

Results of the present study showed that use of herbal extracts containing antimicrobial compounds such as leaf extract of Salvia leriifolia, especially in nanoscales and appropriate concentrations as alternatives to synthetic preservatives, facilitates production of healthier foods with longer shelf life.