A Sanitation Assessment of Food Contact Surfaces in Child Care Centers using Microbiological Analysis and Rapid Sanitation Assays

Author

Catherine Moore Cosby, University of Tennessee - Knoxville

Date of Award

12-2005

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science and Technology

Major Professor

P. Michael Davidson

Committee Members

W.C. Morris, Carol A. Costello

Abstract

Food contact surfaces are a major concern for food service facilities in controlling the spread of foodborne pathogens. Food service areas within these facilities are considered critical to health, and therefore the microbiological quality of these surfaces within child care center food service areas must be surveyed and assessed. The main objectives of this study were: (1) to gather information as to the environmental microbiological quality of food service surfaces and a non-food contact surface in child care centers, and (2) to evaluate several rapid sanitation assays for determining the sanitation quality of food contact surfaces and to determine if the methods have potential for utilization within child care centers.

A microbiological survey was conducted in six (6) Knoxville, TN area child care centers. The facilities represented three large (> 100 children) and three small (< 50 children) centers. Each child care center was tested twice monthly over the course of an eight (8) month period for a total of 16 sampling periods per center. Four areas, one food service area, one diaper changing area, and two food preparation areas (n=288), within each center was sampled. The food service area and the food preparation areas consisted of three food contact surfaces, two food preparation surfaces (i.e. kitchen counters) and one food service surface (i.e. children’s eating table), while the diaper changing area consisted of one non-food contact surface (i.e. diaper changing surface). All surfaces were tested three times daily, pre-opening, lunch time, and following final clean-up of the day, to monitor the microbiological quality of each surface throughout the day.

For the microbiological analysis, results were expressed as the mean aerobic plate count (APC) and coliforms per 50 cm² area and by prevalence rates of the presence of coliforms and E. coli, i.e., the percentage of total samples in which coliforms or E. coli were detected, per 50 cm² area. Mean log APC counts over the survey period were 3.04, 3.93, 3.08, 4.50, 3.45 and 4.16 log₁₀ CFU/50 cm² for centers 1 through 6, respectively. Mean coliform counts were 1.35, 17.96, 5.59, 87.55, 10.22, and 20.43 CFU/50 cm² for the same respective centers. There was a significant difference between counts for center size based on mean log APC with large centers having lower mean log APC (3.55 log₁₀ CFU/50 cm²) than small centers (3.81 log₁₀ CFU/50 cm²). As for coliform counts, there was no significant difference between coliform counts for center size with large centers having a mean coliform count of 35.62 CFU/50 cm² and small centers 10.72CFU/50 cm². Coliforms were detected on 283 of 1,149 (24.7%) samples with counts ranging from 1 to 2,000 CFU/50 cm² while E. coli was detected on 18 of 1,149 (1.6%) samples with counts ranging from 1 to 35 CFU/50 cm².

For the rapid sanitation assays, microbial data and ATP, protein and glucose results were available on 1,129 samples. Correlations between rapid sanitation assays and microbiological analysis (APC) were determined using Spearman’s rho analysis. Correlations (p < 0.01) were found, using Spearman’s rho analysis between the APC and the ATP (r = 0.26) and protein assays (r = 0.16). Rapid sanitation assays were also compared with APC based upon percent agreement, i.e., the number of times the rapid sanitation assays and APC were in agreement of a “clean” or “dirty” surface or area. Surfaces and areas with < 1,000 CFU/50 cm² and ATP value of < 300 relative light units (RLU) or a negative protein or glucose reaction were defined as “clean.” Surfaces with > 1,000 CFU/50 cm² and > 300 RLU or a positive protein or glucose reaction were considered “dirty”. The overall percent agreement between APC and ATP bioluminescence, protein assay and glucose assay was 24.3%, 68.7% and 81.9%, respectively. Therefore, the protein and glucose assays were in agreement more often with the APC analysis. However, the level of RLU to define a “clean” surface using the ATP assay was based upon manufacturer recommendations used for food processing operations and could be modified for child care facilities. Using the manufacturer recommendations for RLU limits, the ATP bioluminescence assay classified only 16.2% of surfaces tested as “clean,” i.e., RLU < 300. The greatest percentage of samples had RLUs between 1,000 and 5,000 (34.7%).

These findings demonstrate that microbial contamination is present on food contact surfaces of child care centers. Due to the high risk of foodborne illness associated with children, the possibility of cross-contamination from food contact or non-food contact surfaces to foods is an aspect of food safety that requires more attention. The findings of the study indicate that rapid sanitation assays may be useful for monitoring the sanitation of food contact surfaces in child care centers. These tests could assist in improving sanitation and preventing cross-contamination by detecting unsanitary surfaces with food residues remaining on the surfaces.

Recommended Citation

Cosby, Catherine Moore, "A Sanitation Assessment of Food Contact Surfaces in Child Care Centers using Microbiological Analysis and Rapid Sanitation Assays. " Master's Thesis, University of Tennessee, 2005.
https://trace.tennessee.edu/utk_gradthes/1851