Evaluation of Antimicrobial Properties of Gliadin Nanofibers Containing Zataria multiflora Boiss Essential Oil and its Effect on Shelf-life Extension of Smoked Salmon Fish Fillet

The aim of this study was to produce electrospun gliadin nanofibers containing Zataria multiflora Boiss essential oil (ZMEO) (5, 10 and 15%, w/w) to create active antimicrobial mats. The minimal inhibitory concentration (MIC) and minimal bactericide concentration (MBC) of essential oil were measured. The ZMEO loaded gliadin nanofibers were characterized for physicochemical, antioxidant and antibacterial activity. Results according to the MIC and MBC revealed that the ZMEO showed the most remarkable bactericidal effect. The nanofibers showed an encapsulation efficiency close to 95% and the presence of ZMEO led to increased contact angle and opaque. ZMEO increased the absorption of color in the visible region, which in turn led to increase of the b* parameter but reduced a* and L* parameters. The nanofibers’ antimicrobial activities were induced by incorporating ZMEO, and Bacillus subtilis was the most sensitive bacterium to ZMEO-containing nanofibers, while Salmonella tiphi was the most resistant. The nanofibers incorporating ZMEO showed good antioxidant properties; this effect was greatly improved when the proportion of added ZMEO was 15%. Then, efficacy of bioactive nanofibers included 5, 10 and 15% (w/w) ZMEO to reduce microbial growth (Listeria monocytogenes) of smoked salmon fish fillet during chilled storage was evaluated; the results indicated that its final population was reduced to about 2.5-3 Log cycles after 16 days of storage at 4 °C in presence of ZMEO, compared with negative control mats produced without the ZMEO. These results suggest that the developed gliadin nanofibers with active substance could be used in designing antimicrobial packaging materials.