Isolation and survival of Yersinia enterocolitica in ice cream at different pH values, stored at -18°c

Abstract

The presence of Yersinia enterocolitica was investigated in 203 samples of industrial (123) and nonindustrial ice cream (80). Two Y. enterocolitica strains were isolated from non-industrial ice cream, which suggests the possibility of post-manufacturing contamination. One strain was typed as B:1A, O: 3,50,51; lis Xz, while the other one was biotyped as: B:1A but not serologically typed. Survival of Y. enterocolitica was investigated by inoculating nine samples of industrially manufactured ice cream to contain 20 CFU/ml of Y. enterocolitica and stored at -18°C for 480 days. The inoculated samples were classified into three different groups according to their pH (Group 1: pH 4-5; Group 2: pH 5-6 and Group 3: pH 6-7). Viability was determined by a combination of direct plating and enrichment. In Group 1, Y. enterocolitica was not detected after 150 days of storage, while in Groups 2 and 3, this microorganism was isolated until day 480 of storage. These findings suggest that the survival time of Y. enterocolitica in ice cream stored at -18°C is significantly (p ≤ 0,05) lower at pH values under 5.

Occurrence of Campylobacter, Salmonella, Yersinia enterocolitica and Listeria monocytogenes in Some Retail Food Products in Novi Sad

“…Although Yersinia enterocolitica is a ubiquitous microorganism, the pig is the major reservoir of the human foodborne pathogen strains (41). According to published data, Yersinia enterocolitica was isolated from chicken carcasses (42), pasteurized milk and ice-cream (43,44), which were also foodstuffs controlled in our pilot investigation. In this pilot investigation, Yersinia enterocolitica was not detected in any of the tested samples.…”

Bioserotypes, virulence genes, antimicrobial susceptibility and genomic diversity of Yersinia enterocolitica isolates from Argentina and Chile

“…The species is classified into six biotypes (B) −1A, 1B, 2, 3, 4, 5, and more than 60 serotypes (O), of which O:3, O:8, O:9, and O:5,27 are mainly involved in human infections. In Argentina, Y. enterocolitica has been isolated from foods in our laboratory (Favier, Escudero, & De, ; Guzmán, de Pederiva, Torres, Eiguer, & Giménez, ; Lucero Estrada, Velázquez, Di Genaro, & de Guzmán, ; Mastrodonato, Favier, & Escudero, ; Pederiva & Guzman, ; Velázquez, Escudero, & Guzman, ). However, these isolates were not associated with foodborne outbreaks or disease in humans.…”