The variety of pourable salad dressings available in large containers for use in food service and home settings has increased in recent years.

The variety of pourable salad dressings available in large containers for use in food service and home settings has increased in recent years. Many had believed that this increased the potential for postprocess contamination, such as at salad bars where portions are removed from the same container by several different people over an extended period of time. The preservation of commercially processed salad dressings depends, in part, on mild heat treatments that reduce, control or eliminate microorganisms. The presence of acetic acid, lactic and citric acids, a low pH, salt, natural antimicrobials and preservatives, such as sorbic acid or benzoic acid, create a harsh environment for pathogens. Researchers undertook a study to determine the death rates of various pathogens in shelf-stable, dairy-based, pourable inoculated commercial full-fat ranch salad dressings. They found that regardless of the initial inoculum population, the pathogens rapidly died in all salad dressings. Salmonella was undetectable in all dressings within one day, and the number of E. coli O157:H7 and L. monocytogenes bacteria were reduced to undetectable levels by enrichment between one and eight days and two and eight days, respectively. E. coli O157:H7 was not detected in four of the 10 salad dressings stored for two or more days, and in nine of the 10 dressings stored for six or more days after inoculation. In essence, shelf-stable, dairy-based, pourable ranch and blue cheese salad dressings manufactured commercially and stored at 25 C do not support the growth of Salmonella, E. coli O157:H7 or L. monocytogenes. They should not be considered as potentially hazardous foods as defined by the FDA Food Code. Contact: Michael Doyle, Center for Food Safety, University of Georgia, Griffin Campus, Melton Building, Griffin, GA 30223. Phone: [phone]. Fax: [phone]. Email: [e-mail].