Cheese is one of the most prominent dairy products that contains almost all essential amino acids. Cheese ingredients and environmental conditions often cause excessive growth of fungi and bacteria on the cheese surface. Therefore, the use of appropriate packaging methods is considered a fundamental step to increase the shelf life of dairy products, especially cheese. Therefore, this research aims to investigate the characteristics of biodegradable carboxymethyl cellulose film containing organic zinc nanoframework at three levels of 1, 2, 3% and thyme essensial oil at two levels of 250 and 500 microliters and its effect on the characteristics of Iranian white cheese. The effects of Zn-nMOF and thyme essential oil on structural, mechanical, thermal, inhibitory and microbial properties were investigated. The results of infrared spectroscopy showed the creation of more hydrogen bonds between the Zn-nMOF and the film matrix. The results of the thermal properties showed that the melting point increased and decreased with the addition of Zn-nMOF and thyme extract, respectively. Also, the results showed that with the addition of essential oil and Zn-nMOF, the resistance of films against visible light and permeability to water vapor increased. The results of the mechanical test showed an increase in elongation, tensile strength and a decrease in Young's modulus by adding more essential oil and a decrease in elongation and an increase in tensile strength and Young's modulus by increasing the percentage of organic zinc nanoframework. Also, the effect of the biodegradable film on the packaged cheese showed that with increasing the content of essential oil and Zn-nMOF, the moisture content and pH of packaged cheeses were better preserved. The results of the microbial tests showed the best results for the cheese packed with film containing 3% Zn-nMOF and 500 microliters of essential oil. Finally, the results of the sensory eva‎luation showed that the use of films does not have an adverse effect on the sensory characteristics of cheese. Therefore, these films can be used to improve the shelf life of cheese without affecting the sensory characteristics.

مهدي كديور , نوشين نوشيرواني

هاجر شكرچي زاده , ابراهيم قاسمي