Assessment of the microbiological quality and wash treatments of lettuce served in University restaurants

One hundred and forty-four samples of lettuce from 16 University restaurant s were analyzed. The mesophilic aerobic counts of all samples ranged from 3 .01 to 7.81 log(10) CFU g(-1). Results of total coliforms ranged from < 0.4 7 to > 3.38 log(10) most probable number (MPN) g(-1). Of the lettuce sample s, 25.7% harbored Escherichia coli, 22.9% Staphylococcus aureus and 84% gro up D streptococci. Similarly, 10.4% of the samples harbored Aeromonas hydro phila, 2.8% Pseudomonas aeruginosa, and coliforms such as 14.6% Citrobacter freundii, 8.3% Klebsiella pneumoniae, 4.2% Enterobacter cloacae and 1.4% P rovidencia spp. Salmonella, Shigella and E. coli O157:H7 were not detected. When sodium hypochlorite or potassium permanganate solutions were used in washing procedures, the aerobic microorganisms were reduced by more than tw o log units, and total coliforms by at least one log. (C) 2000 Elsevier Sci ence B.V. All rights reserved.