Quantifying operator effect on recovery of TVC from beef and sheep carcases using the surface sponge sampling method.

Summary

The safety and quality of beef products are commonly assessed by measurement of Total Viable Counts - TVC - using a surface sponge sampling method. 
This test normally involves a single sponging of one to three 100 cm2 areas on the carcase surface by abattoir operators and inspectors. Each sampler potentially introduces variation based on individual sampling methods. 
As such, interpretation of carcase TVC levels depends on understanding the inherent uncertainty due to the sampling procedure, which could lead to improved methods with lower test variability.
This project developed knowledge of operator effect on the recovery of TVC from meat carcase surfaces.
The experimental design quantifies the percent of the TVC recovered from the carcase surface based on the force used by the operator to sponge the surface.
In addition, measurements of recovery efficiency include the percent TVC removed as a function of multiple sponging events, as well as the age of the carcase - ‘cold' versus ‘hot' sampling. The results of this project provide a more accurate interpretation of factors that influence the microbiological quality of meat products.
Two separate portions of beef flank were analysed in the laboratory to determine the level of TVC recovered by five sequential spongings of a single 100 cm2 area. Two 100 cm2 sites were tested per flank. 
An average of 66% of TVC was recovered after five spongings rump, brisket and flank on a single hot boned carcase was similarly tested and showed than an average of 52% of TVC was recovered after five spongings. 
A comparison between operators each sponging a carcase once showed considerable variation between operators.
The distribution of percent recovery for combined carcase sampling sites showed a peak between 30 and 50% recovery, with an average of 37% (sd=23).  This indicates that the standard method does not recover approximately 63% of the detectable TVC count.