THE ANALYSIS OF EGG WASH WATER FOR THE RAPID ASSESSMENT OF MICROBIOLOGICAL QUALITY

A total of 101 egg wash water samples from five different egg grading stations in eastern Ontario were analyzed for a variety of physical an d chemical variables in an attempt to find a correlation with total ba cterial counts. Temperature, pH, total chlorine, and percentage transm ission at 600 nm (%T) were found to be significant variables, and a mu ltiple regression equation was derived that accounted for 65% of the t otal variation. The equation was used to classify wash water samples a s acceptable (less-than-or-equal-to 10(5) cfu/mL) or unacceptable and correctly classified 77.2% of the samples. Classification of a second (validation) data set from 58 wash water samples was correctly predict ed in 72% of the cases. The predictive value of the equation was espec ially good for those wash water samples obtained from stations that ha d used a chlorinated alkaline detergent, 90.4 and 100% for the modelin g and validation data, respectively. Maintenance of wash water at reco mmended levels for temperature and PH (i.e., greater-than-or-equal-to 40 C and pH greater-than-or-equal-to 10) was insufficient to ensure ba cterial numbers would be less-than-or-equal-to 10(5) cfu/mL. Under nor mal operating conditions a minimum total available chlorine concentrat ion of .45 mg/L should be maintained in wash water to ensure that bact erial numbers are kept at an acceptable level. Monitoring of temperatu re, pH, total chlorine, and %T will assist in maintaining wash water q uality and minimize the number of samples returned to laboratories for microbiological analysis.