Foodborne illness continues to be a public health concern, especially due to improper washing and sanitization of tableware items in foodservice establishments. This could lead to cross-contamination of ready-to-eat foods and may even lead to biofilm formation if inadequate washing becomes a long-term practice. As a result, cleaning and sanitization of all tableware items should be maximized to minimize this risk. The FDA Food Code (2005) and NSF International standards require a 5-log bacterial reduction and the complete removal of all food soil when testing the efficacy of a chemical sanitization method. However, as a cost savings practice, foodservice establishments usually wash several batches of tableware items in a single lot of cleaning chemicals. As a result, there is a need to determine the maximum number of warewashing cycles that can still achieve the Food Code and NSF standards, when a single lot of detergent/rinse water/sanitizer is used.
The first study of this thesis (Chapter 2) evaluated the efficacies to two traditional (sodium hypochlorite and quaternary ammonium) and two newer (neutral electrolyzed-oxidizing water and PRO-SAN®) sanitizers. This was achieved by investigating the survival of Escherichia coli K12 and Listeria innocua. These bacterial species were inoculated into cream cheese and pasteurized whole milk and subsequently used to soil ceramic plates, plastic serving trays and drinking glasses. These tableware items were washed with mechanical (49°C) and manual (43°C) dishwashers then treated with one of the four sanitizers. After the washing protocol, bacterial counts were determined on the surface of tableware items using the plate counting method, and thus the maximum number of warewashing cycles were determined. Results showed that the newer sanitizers are more efficient than the traditional sanitizers. This study also concluded that mechanical washing is more efficient than manual washing. Lastly, the type of material used to make the tableware plays a role in the washing efficiency, as more glassware items were washed while still achieving a 5-log bacterial reduction when compared with ceramic plates and plastic trays.
The second part of this thesis (Chapter 3) investigated the effect of the various sanitizers on removing various milk-based products (whole, 2% fat, chocolate low fat and skim milk) from underlining glass surfaces. Atomic force microscopy was used to determine the thicknesses of milk-films left after attempts to clean the glass surfaces. These thickness measurements were then analyzed to determine the adhesion potential between the residual milk samples and the glass surfaces. Results showed that PRO-SAN® significantly reduced the amount of residual food soil when compared with the other sanitizers. This was due to the presence of sodium dodecylbenzene sulfonate (surfactant) in the PRO-SAN® formulation. The data also showed that whole and chocolate milk would be more difficult to clean when compared with 2% and skim milks.
These studies are important because these newer sanitizers are less hazardous and have a lower negative impact on the environment. Information obtained from this study could be used by foodservice institutions to minimize the cost of food contact surface cleaning while still meeting FDA mandates.