University of Guilan Caspian Journal of Environmental Sciences 1735-3033 24 3 2026 07 01 Development and characterization of biodegradable nanocomposite films incorporating natural antimicrobial agents for dairy product 729 736 9786 10.22124/cjes.2026.9786 EN Ainur Zheldybayeva Department of Applied Biotechnology, Almaty Technological University, Almaty, Kazakhstan Zhuldyz Yembergenova Department of Chemistry and Food Technology, K.Zhubanov Aktobe regional university, Aktobe, Kazakhstan Sholpan Amanova Department of Food Safety and Quality, Almaty Technological University, Almaty, Kazakhstan Ayaulym Suyundikova Department of Applied Biotechnology, Almaty Technological University, Almaty, Kazakhstan Roza Sarmanova Department "Biology, Plant Protection and Quarantine" of Saken Seifullin Kazakh Agrotechnical Research University, Kazakhstan Muratkali Aliya Department of Chemistry and Food Technology, K.Zhubanov Aktobe regional university, Aktobe, Kazakhstan Gulmira Kassenova Head of the Biotechnology Laboratory at the Research Institute of Biotechnology and Ecology, Zhetysu University named after I.Zhansugurov, Taldykorgan, Kazakhstan Georgiy Afonin Department of Oncology Asfendiyarov Kazakh National Medical University, Almaty, Kazakhstan Journal Article 2026 07 28 Currently, the environmental issues arising due to pollution with plastic packaging waste in the food industry have turned into a critical problem for developing countries like Kazakhstan. The objective of this study was to create and test the properties of nanocomposite biodegradable films consisting of polylactic acid and starch, loaded with montmorillonite nanoclay and thyme essential oil as a part of the development of dairy packaging films. Films were produced using solvent casting technique at various concentrations of nanoclay (1, 3, and 5 wt%) and thyme essential oil (2 wt%), and tested for their mechanical, barrier, structural, antimicrobial, and practical properties. It has been found that films with 5 wt% of nanoclay demonstrated increased tensile strength by 70% (18.4 to 31.2 MPa) and decreased water vapor permeability by 50% (42.8 to 18.4 g m-2 day-1). SEM and XRD analyses demonstrated the appropriate distribution of nanoparticles and increased interlayer distance from 1.52 to 1.82 nm. Films with thyme essential oil possessed good antimicrobial effect against Staphylococcus aureus (halo diameter 19.2 mm) and Escherichia coli (15.6 mm). According to the experiment conducted in refrigerated conditions of milk package testing, the improved film (NC3-TO) decreased the total amount of microorganisms to 68.5 log CFU mL-1 on the 21st day of storage while 56.8 log CFU mL-1 were obtained using traditional polyethylene packages (p < 0.001). Thus, the shelf life increased by seven days. Nanocomposite films designed during this research might be a good replacement for conventional plastics in the Kazakhstan dairy market.<br /><strong> </strong> https://cjes.guilan.ac.ir/article_9786_6e78ff76cb022e9ef8d98aae7bb03d3d.pdf