ASSESSMENT OF THE MICROBIOLOGICAL QUALITY OF READY-TO-USE VEGETABLES FOR HEALTH-CARE FOOD SERVICES

The microbiological quality of ready-to-use (RTU) vegetables, includin g chopped lettuce, salad mix, carrot sticks, cauliflower florets, slic ed celery, coleslaw mix, broccoli florets, and sliced green peppers wa s determined before and after processing. Microbial profiles were obta ined 24 h after processing and on days 4, 7, and 11 after storage at 4 and 10 degrees C to simulate temperature abuse. In addition, the micr obial profiles of four RTU vegetables, coleslaw mix, salad mix, caulif lower florets, and sliced green peppers were determined 7 days after d istribution to a select group of Ontario hospitals. RTU vegetables, wi th the exception of green peppers, showed up to a 1-log decrease in ae robic colony counts after processing. These counts increased to prepro cessing levels after 4 days of storage at both 4 and 10 degrees C. RTU vegetables stored at temperature abuse conditions (10 degrees C) had significantly higher counts (P < 0.001) on days 4 to 11 as compared to those stored at 4 degrees C. Green peppers had the highest bacterial counts while cauliflower and chopped lettuce had the lowest counts at both storage temperatures (P < 0.05). Increased levels of Listeria mon ocytogenes in RTU vegetables were associated with temperature abuse. L evels of >100 MPN/g for L. monocytogenes were detected in 8 of 120 (6. 7%) samples stored at 10 degrees C but not in 175 samples stored at 4 degrees C after 7 days (P < 0.05). Overall, L. monocytogenes was detec ted in 13 of 120 (10.8%) RTU vegetables stored for up to 11 days at 10 degrees C and 5 of 176 (2.8%) samples stored at 4 degrees C (P < 0.05 ). E. coli was detected in 2 of the 120 (1.7%) processed RTU vegetable s after day 7 of storage at 10 degrees C and 1 of the 65 (1.5%) unproc essed vegetables from the same batches of vegetables used for processi ng. This indicator organism was not detected in RTU vegetable samples stored at 4 degrees C or in any of the RTU vegetable samples obtained from hospital coolers. Other pathogenic bacteria, such as Salmonella s pp., Campylobacter spp., Yersinia enterocolitica (serotype O:3) and ve rocytotoxigenic E. coli (VTEC) were not detected in any of the RTU veg etables tested. Recommendations regarding processing, distribution, an d storage of these products are presented.