Evaluation of the Effect of the Film Prepared on the Basis of Polylactic Acid Tragacanth Gum Films Containing Origanum Vulgare Essential Oil on the Shelf Life and Characteristics of Feta Cheese

Introduction: chemical preservatives are widely used to increase the shelf life of food products. But due to their disadvantages, today the main research is in the field of   using natural preservatives. This study was carried out to prepare a film based on polylactic acid and tragacanth gum containing Origanum vulgare essential oil (OVEO) on the microbial, chemical and sensorial properties of feta cheese. Methods: OVEO was extracted by steam distillation and its composition was determined by gas chromatography-mass spectrometry (GC-MS). The most important parameters of PLA films were determined: thickness, turbidity and humidity. The antibacterial effects of films were evaluated against four common pathogenic bacteria (Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and Escherichia coli O۱۵۷:H۷) by disk diffusion method. Results: The results of physical properties showed that there was no significant difference in film turbidity when adding different OVEO concentrations (p>۰.۰۵). In part of moisture and turbidity, there was a significant difference between films containing different concentration of OVEO and pure film (p<۰.۰۵). The results of the antimicrobial activity showed that the Staphylococcus aureus (۱۰ mm), E. coli (۶ mm), Listeria and Salmonella (۱ mm), were the most sensitive organisms respectively. The most sensitive and largest diameter of the inhibition zone was in Aspergillus (۱۳ mm). Conclusion: Based on the findings, the film based on polylactic acid and tragacanth gum containing OVEO can be successful natural preservative with the least adverse effect on the properties of different products. Food has a wide application in the industry.

کلیدواژه ها:

Polylactic Acid ، Tragacanth gum ، Origanum vulgar ، Feta cheese