Evaluation of two antimicrobial packaging films against Escherichia coli O157:H7 strains in vitro and during storage of a Spanish ripened sheep cheese (Zamorano)

Abstract

The antimicrobial activity of two packaging films (polypropylene-PP-and polyethylene terephthalate-PET-) coated with different concentrations (0, 4, 6 and 8%) of essential oil from Origanum vulgare (OR) and Ethyl Lauroyl Arginate HCl (LAE) was tested against two E. coli O157:H7 strains using in vitro systems and a raw milk sheep cheese model (Zamorano). The influence of the antimicrobials on the sensory attributes of cheese was also evaluated. For both strains, the MBC (minimum bactericidal concentration) values were identical to their respective MIC (minimum inhibitory concentration) values and lower for LAE (25 mg/l) than for OR (200-400 mg/l). PP and PET films coated with OR were tested by a vapour phase assay and the Japanish Standard method (JIS Z 2801:2000). Both films coated with LAE were tested by an agar diffusion method. Overall, in vitro tests were effective against both strains. The inhibitory activity depended on the active compound concentration, the target strain and the packaging material, PET being more effective than PP. For inoculated cheese slices, OR and LAE PP films did not effectively decrease E. coli O157:H7 counts after 7-days cold storage. PET films incorporating 6 and 8 % of OR and LAE significantly (p< 0.05) decreased the numbers of both strains and also did 4% for the reference and wild strain depending on the antimicrobial. LAE PP, OR PET and LAE PET did not significantly (p> 0.05) affect sensorial characteristics of Zamorano cheese. Packaging with PET films coated with ≥ 6% LAE concentrations might be useful in reducing E. coli O157:H7 numbers in sheep cheese.

Antibacterial and antifungal LDPE films for active packaging

“…One major drawback of essential oils molecules is their volatile nature; therefore, the main applicative methodology for their incorporation into polymers is by coating technologies. [18,19] Once the essential oils are directly incorporated into the polymer matrix by high-temperature melt processing, antimicrobial activity is achieved. [16,18,[20][21][22][23][24][25][26][27][28][29][30][31][32][33] However, this activity is evaluated, in most cases, immediately after film production, [29,[33][34][35] while the challenges associated with the controlled and prolonged activity of these films are not addressed.…”

Applications of Edible Coatings Formulated with Antimicrobials Inhibit Listeria monocytogenes Growth on Queso Fresco

“…Sensory panels evaluating medium-well roast beef samples coated with a chitosan solution formulated with LAE were able to identify the difference between treated and control samples immediately after surface coating treatments but not on day 15 (Wang et al, 2015). Similarly, Otero et al (2014) reported that polypropylene and polyethylene tetrephalate films coated with LAE did not significantly affect the organoleptic properties of Zamorano cheese slices. Therefore, chitosan solutions formulated with LAE may not negatively influence the organoleptic properties of cheese, but future studies are warranted.…”

Use of herbs, spices and their bioactive compounds in active food packaging

“…Some commodity polymers such as low density polyethylene (LDPE) [22][23][24][25][26] , poly(vinyl chloride) (PVC) 22 and polypropylene (PP) [27][28][29] have been tested as adequate matrices to host different herb extracts. But in recent years biopolymers based on starch, cellulose derivatives, chitosan/chitin, gums, proteins obtained from animal or plant-sources, and lipids have emerged as environmentally-friendly alternatives to synthetic polymers as carriers of herb extracts (Table 1).…”