Isolation and survival of Pseudomonas aeruginosa in yogurt fortified with pomegranate dibs

Abstract

This study aimed to study the prevalence of Pseudomonas aeruginosa in 60 random yogurt samples (20 each of plain small-scale, plain large-scale, and fruit yogurts) collected from Assiut City, Egypt from December 2023 to March 2024. Identification of Ps. aeruginosa was performed using biochemical and molecular methods. Pomegranate dibs were applied to evaluate its inhibitory effect on Ps. aeruginosa growth during the manufacture and storage of yogurt in at refrigerator (4°C). Results revealed that Ps. aeruginosa could be isolated from 6 (10 %) of the 60 examined yogurt samples, which were identified by chemical tests. Using PCR, the results indicated that 2 (3.33%) of the examined yogurt samples were contaminated with this bacterium. Unexpectedly, Ps. aeruginosa was isolated from large-scale plain yogurt samples with an incidence of 10%. The minimum inhibitory concentration (MIC) of Pomegranate dibs against Ps. aeruginosa growth was 4%. The results of the Pomegranate dibs 6% yogurt samples that inoculated with Ps. aeruginosa was the most effective one in which 6% pomegranate dibs sharply reduced the count of Ps. aeruginosa, until completely inhibited at the 7^th day of yogurt storage, compared to the control group, in which the organism still alive until the end of storage period (15^th day). The sensory evaluation of yogurt prepared by adding different concentrations of pomegranate dibs revealed that the manufactured yogurt acquired a higher score for flavor, body, and texture than the control, using the natural affordable pomegranate dibs as antibacterial against Ps. aeruginosa growth has been found.