Enhancing the Quality and Shelf Life of Soft Cheese Using Zinc Oxide and Chitosan Nanoparticles

Soft cheese, an early food introduced into the human diet for its nutritional value, is highly susceptible to microbial contamination by spoilage and/or pathogenic microorganisms during storage. This study evaluated the effects of Zinc oxide (ZnO) nanoparticles (10 mg/ml, G1), chitosan nanoparticles (500 µg/ml, G2), and their combination (G3), compared to a control group (C), on the coagulation time, sensory profile, acidity percentage, and microbiological quality of soft cheese. Results showed significant differences in coagulation time among the groups, with mean times (hour: minute) of 04:20 for C, 03:05 for G1, 02:10 for G2, and 00:51 for G3. Sensory evaluation revealed that treated groups, particularly the combination group (G3), received the highest scores, maintaining acceptability up to 21 days for the control, 39 days for G1, 42 days for G2, and 48 days for G3 under refrigeration. Acidity percentages at 21 days were 0.55 for the control and 0.19 for G3, indicating a slower increase in acidity in treated samples. Microbiologically, treated cheeses showed significant improvement compared to the control. Coliform and E. coli were undetectable in all samples during refrigeration. Mould appeared at 21, 36, 42, and 48 days for C, G1, G2, and G3, with mean counts of 1.6±0.05, 1.5±0.2, 1.4±0.02, and 1.2±0.08 log10 CFU/g, respectively. Yeast was detected at 15, 27, 30, and 36 days with mean counts of 1.7±0.05, 1.9±0.1, 1.6±0.03, and 1.7±0.08 log10 CFU/g, correspondingly. In conclusion, the soft cheese treated with a combination of chitosan and ZnO nanoparticles extended shelf life to 48 days with improved sensory, acidity, and microbiological profiles compared to 21 days for the control group.