Effects of LLDPE/Clay Nanocomposite Films Including Bioactive Compounds on The Microbiological Quality of Fresh Kashar Cheese

Abstract

Emerging as a significant innovation in the food industry, active packaging extends shelf life, enhances safety, and maintains food quality by incorporating bioactive components like antimicrobial agents directly into packaging materials. In this context, polymer nanocomposites-particularly those reinforced with clay nanoparticles-have recently gained significant interest due to their enhanced functional properties. The cheese industry is one of the sectors with strong potential for applying such materials, as evidenced by recent developments in edible films for cheese. This study aimed to investigate the effects of active clay nanocomposite packaging films based on linear low-density polyethylene (LLDPE) containing eugenol (EUG) / thymol (THY) or carvacrol (CRV) loaded layered montmorillonite (MMT) or tubular halloysite (HNT) nanoclays. The study focused on their impact on the natural microbial load of kashar cheese, including total mesophilic aerobic bacteria (TMAB), total coliforms (TC), total lactic acid bacteria (LAB), and total yeast-mold (TYM), as well as on the presence/ growth of Listeria monocytogenes, Staphylococcus aureus, and Aspergillus niger, along with pH values, after storage at 10 degrees C for 30 days with analysis conducted every 10 days. The results showed that when prioritizing the packaging materials with the greatest impact on the microbial populations of kashar cheese, the order observed was as follows: THY-HNT for TMAB; EUG-MMT, CRV-HNT and THY-HNT for LAB; and CRV-HNT and THY-HNT for TYM. Moreover, S. aureus was not found in any of the kashar cheese samples. Furthermore, CRV-HNT and EUG-MMT films exhibited fungicidal properties throughout storage, leading to a decrease in mold spore counts, whereas THY-HNT films showed fungistatic effects. Additionally, CRV-HNT and THY-MMT packaging samples effectively limited growth of L. monocytogenes. As well, the pH values (5.15-5.52) of the cheese samples fluctuated during the storage period except for the control samples. Overall, the study showed that active nanocomposite films (ANFs) have the potential to extend shelf life, maintain safety and improve the overall quality of kashar cheese during storage.