Characterization of a high-performance edible film based on Salep mucilage functionalized with pennyroyal (Mentha pulegium).

Salep mucilage was extracted from salep tubers and used to produce edible films containing pennyroyal extracts (PER) (0, 0.5, 1, and 1.5% v/v) as a new antibacterial/antioxidant edible film, and their physical, mechanical, permeability, thermal, microstructural and antibacterial properties were measured. Results showed that pulegone (20.8%) and menthone (34.7%) were the most representative components of PER. Water vapor permeability (WVP) was determined in the range of 2.26-2.81 × 10-11 g-1s-1Pa-1. Oxygen permeability (O2P) was found between 30.53 and 35.64 cm3μmm-2d-1 kPa-1. As expected, the PER concentration from 0% to 1.5% (w/w) increased the elongation at break (EAB) but decreased tensile strength (TS) and Young's modulus (YM). The 2, 2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2, 2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) methods were used to evaluate the antioxidant activity. Based on the results of the agar disc diffusion test, the antibacterial properties significantly increased with the incorporation of PER. Salep mucilage based (SBM) edible films containing PER showed a powerful antibacterial activity against Yersinia enterocolitica, Staphylococcus aureus, and Shewanella putrefaciens among bacteria tested.