ARTICLE: FOOD PREPARATION & MANUFACTURING - RESEARCH ARTICLE

Microbiological contamination of beverage dispenser tips in university foodservice operations

C. LAKSHMANAN and D. Schaffner. Dept. of Food Science, Rutgers, The State Univ. of New Jersey, 65 Dudley Rd., New Brunswick, NJ 08901-8520

We have previously observed that beverage dispenser tips often contain high microbial counts (Buckalew et al., 1996). These are among the most problematic surfaces found in foodservice establishments. The objective of this research was to determine the cause of these high microbial counts and find a practical solution to the problem. Research was conducted on beverage dispensers in use in university dining halls and on a new juice dispensing machine, identical to the ones used in the dining halls, placed in our laboratory. Con-Tact-It tape was used to transfer the microorganisms from dispenser tip to plate count agar. Orange juice was dispensed through the laboratory machine and the total plate counts on the dispenser tips were measured at appropriate time intervals. The effect of sanitizer was determined by cleaning the machine using different concentrations of sanitizing solution (100, 150 and 200 ppm (parts per million) of chlorine) and observing the microbial counts throughout the next day when the machine was in use. Only 100 ppm was used in the university foodservice machines. Results from beverage dispensers located in dining halls and from the machine located in our lab were similar: microbial counts tended to be highest immediately after dispensing a beverage, and decline gradually over time. Swab tests on the inside of the plastic dispenser tips suggest the possibility of biofilm formation inside the tips. This was supported by observations using fluorescent microscopy. Initial measurements of the microbial contamination were low in the new laboratory-based machine, but increased over time. Sanitizing with 200 ppm chlorine gave a three-fold reduction in the microbial count and sanitizing with 150 ppm chlorine gave a two-fold decrease compared to sanitizing with 100 ppm. These results suggest that using a higher concentration of sanitizer can help reduce microbial counts on the beverage dispenser tips.

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