Development and testing of a prototype automatic trim sampler
Citation
Badoni, M., Klassen, M.D., Wang, H., Youssef, M.K., Devos, J., Gill, C.O., Yang, X. (2017). Development and testing of a prototype automatic trim sampler. Food Control, [online] 77 82-87. http://dx.doi.org/10.1016/j.foodcont.2017.02.005
Plain language summary
The beef trim for making raw ground beef or beef patty products in a processing plant is generally tested for E. coli O157, a bacterial pathogen capable of causing disease in human small intestine. The N60 method, manually excising 60 pieces of meat from a production lot, is mandated by regulatory agencies in North America. This method has been argued for its intensive resource demand and its inability to fully represent a production lot. This study was aimed at designing and testing a prototype automatic sampler that would reduce cost and be able to obtain a better representation of trim samples. This study first tested the efficacy of a more technically achievable method, swabbing sampling, for detecting total E. coli, which is regarded as an indicator organism for the presence of pathogens like O157. The study detected more E. coli positive samples using manual swab sampling compared to excision sampling, suggesting the relatively higher sensitivity of swab sampling for recovering E. coli from beef trims. We further designed an automatic beef trim sampler based on the swabbing sampling mechanisms. The newly constructed sampler yielded an optimal sampling scheme, resulting in similar bacterial counts to manual swabbing method for indicator organisms including E. coli and two other types of bacteria often present on meat. Our study suggests the automatic sample collection from beef trim for the detection of E. coli is possible. The in-plant validation of this automatic trim sampler for detecting E. coli O157 is anticipated.
Abstract
The N60 method currently mandated by regulatory bodies in North America for routine testing of beef trim for Escherichia coli O157:H7 requires that 60 slices of beef, up to 375 g, be removed from combo bins containing up to 10,000 lb of beef trim. The objective of this study was to design and test a prototype automatic trim sampler that would reduce the resource demands of, and result in more representative sampling than, N60. Ten commercial combo bins were each sampled at five locations of each of four levels, by swabbing an area of 1000 cm2 and by excision of up to five meat pieces with a total area of 100 cm2. The samples were enriched in modified Tryptone Soy Broth supplemented with novobiocin at 20 mg/L, and tested for generic E. coli using real-time PCR. A prototype trim sampler was constructed and tested for recovery of aerobes, coliforms and E. coli and was compared to manual swabbing, using beef trim artificially contaminated with E. coli. Overall, 21.5% of excision samples and 38.0% of swab samples from combo bins were positive for E. coli. Of the 40 levels that were sampled, 50.0% were positive by excision, 70.0% were positive by swabbing. The sampler, designed based on swab sampling, could process trim of ≤1 kg. Of the 12 pairs of manual sampling and automatic sampling compared, ≥ 8 were not significantly different for recovering each of the three groups of indicator organisms (P > 0.05). The findings of this study show that swab sampling can be more sensitive and representative than excision sampling for recovering small numbers of E. coli from beef trim and the prototype sampler can have efficacy comparable to manual swabbing for recovering all three groups of indicator organisms from beef.