Abstract

Background:
Cheese preservation remains a substantial challenge in food safety, particularly for white soft cheese, due to its short shelf life. Consequently, the use of natural preservatives, especially plant-derived extracts, has received increasing attention.

Aim:
This study aimed to evaluate the effectiveness of pomegranate peel extract (PPE) against Escherichia coli O157:H7 and Pseudomonas aeruginosa. This study highlights the capability of using agricultural waste as a sustainable source of natural antibacterial and antioxidant compounds, serving as an alternative to synthetic preservatives to extend shelf life and improve the microbiological safety of white soft cheese.

Methods:
Pomegranate peels were extracted with 70% ethanol, and a cytotoxicity assay was used to assess the safety of the extract. The total phenolic content, total flavonoid content, DPPH percentage, and extraction yield percentage were determined. Antibacterial activity was evaluated by determining the MIC and MBC. Based on their results, 2 % PPE was selected for incorporation into cheese. The effect of 2% PPE on the survival of E. coli O157:H7 and P. aeruginosa was monitored during storage. Furthermore, sensory characteristics were evaluated, and shelf life was determined based on chemical and microbiological parameters.

Results:
Total phenolic, flavonoid, DPPH%, and extraction yield% were 283.05 mg GAE/g, 85.40 mg QE/g, 90.10%, and 30.00 %, respectively. The MIC values were 1% and 1.5% for E. coli O157:H7 and P. aeruginosa, respectively, while the MBC values were 1.5% and 2%, respectively. The application of 2% PPE resulted in the complete elimination of E. coli O157:H7 within 28 days of storage and P. aeruginosa within 28 and 21 days of storage, respectively. Shelf-life evaluation demonstrated an extension of shelf-life up to 35 days in PPE-treated cheese compared with the control (14 days). PPE 2% reduced the sensory attributes of the treated cheese compared with the control.

Conclusion:
Pomegranate peel extract exhibited strong antibacterial and antioxidant properties. Its application in soft cheese represents a sustainable strategy for valorizing agricultural waste while producing natural bioactive compounds that enhance cheese safety and extend its shelf life.

Key words: Cytotoxicity; E. coli O157:H7; Pomegranate peel extract; Pseudomonas aeruginosa; White soft cheese.