Purpose: The objective of this study was to understand the levels of bacterial levels and fecal contamination indicators in specialty salads and leafy green salads as a function of restaurant ownership (corporately owned versus independently owned), salad types (leafy green versus specialty salads) and customer (low traffic versus high traffic) volumes.
Methods: The salads (100 specialty and 100 leafy green salads) were obtained from 5 corporately owned (CO) restaurants and 5 locally owned (LO) restaurants during periods of high customer traffic and low customer traffic. Of these, 50 specialty salads and 50 green leaf salads were obtained from high and low customer traffic periods and screened for aerobic bacterial counts (APC), coliforms, Escherichia coli, Enterococcus spp. somatic coliphages, and male-specific coliphages.
Results: E. coli, Enterococcus, male-specific and somatic coliphages were present in 19%, 78.5%, 20%, and 22.5% of the restaurant salad samples, respectively. Indicator organisms were higher in specialty salads compared to leafy green salads. Overall, restaurant type was shown to influence the concentration of indicator organisms in restaurant salads. Two-way ANOVA analysis showed that salads from LO restaurants had significantly (P = <0.05) higher concentrations of APC, Enterococcus, and male-specific coliphages than salads purchased from CO restaurants. Total coliforms and somatic coliphages were significantly (P = <0.05) higher in CO restaurants. Two-way ANOVA analysis found that there was no significant differences observed for the concentrations of APC, total coliforms, E. coli, Enterococcus, and male-specific and somatic coliphages for salads purchased during different volumes of customer traffic.
Significance: These results imply that salads especially specialty salads, can be a vehicle for fecal contaminants and that microbiological quality within corporately owned and locally independently owned restaurants is approximately the same. These results can assist the restaurant industry understand the potential vulnerabilities in their practices.