Physical, mechanical, and bioactive properties of edible film based on sodium alginate enriched with Lythrum salicaria L. extract

Abstract

An active film was developed by incorporating Lythrum salicaria L. ethanol extract (LSE) into sodium alginate at concentrations of 0.5, 1.0, 1.5, and 2.0% v/v. The effects of LSE on the microstructure and physicochemical and bioactive properties of the films were evaluated. The ABTS antioxidant capacity of film samples was found to be 7.56-160.61 μmol TE/mg film, and the DPPH radical scavenging capacity was estimated to be 2.51%-38.44%. Films containing LSE showed remarkable antibacterial activity against both gram-positive and gram-negative strains. Moreover, it was also determined during the 14-day storage of raw ground meat samples under refrigerator conditions that, in comparison to the control films, the LSE-added active film samples were more effective on the microbiological characteristics of the product. It was determined that, in samples with LSE addition rate exceeding 0.5%, extract was not homogeneously distributed within the polymer matrix and decreased the tensile strength. Practical applicationsThe presented study provides elaborate characterization analysis of the edible film to prove the effectiveness of using herbal extract incorporated active edible films for shelf life extension and packaging of raw meat. It was found that, in relation with the amount of LSE additive in films, the hydrophilic character of films increased, and it increased the biodegradability of film in the soil. In conclusion, it can be stated that sodium alginate-based edible films enriched with LSE have the potential of use in food packaging.

Evaluation of Antimicrobial and Antioxidant Activities of Alginate Edible Coatings Incorporated with Plant Extracts

“…As expected, the film with alginate and TPP (no extract) did not show any inhibitory activity against the studied bacteria and acted as a control, since all microorganisms grew in an exponential manner when exposed to this film. This result is similar to that reported by Aydin and Zorlu [46] and Engin et al [47].…”

“…There are several studies reporting the incorporation of PEs into alginate films [46,47,[57][58][59]. However, none of them incorporated extracts of licorice, eucalyptus, sage, and thyme, attesting to the innovation of the present work.…”

“…However, none of them incorporated extracts of licorice, eucalyptus, sage, and thyme, attesting to the innovation of the present work. Additionally, the antibacterial activity of films is usually determined by the disc diffusion method [46,47,57,60] and not by the viable cell count assay, as performed in this study, which mimics more accurately the real interaction of contaminant microorganisms and films. Nevertheless, it is possible to compare the results of this work with studies that produced films with other polymers and/or incorporated other extracts into films.…”

“…Initially, the antioxidant activity of the films dissolved in water (results not shown) was tested, as performed in various studies [47,[69][70][71]. However, it was verified that the values of antioxidant activity were almost residual and probably did not correspond to the real ones.…”