Much of the dark meat from U.S. broilers continues to be exported to other countries because of local consumers’ long-standing and strong preference for white breast meat. In this review we will discuss what causes meat colour differences and how environmental and genetic factors influence the colour of poultry meat. It is well documented that the darker colour of leg/thigh meat is due to the larger amount of myoglobin and haem pigments, as well as a higher pH when compared to breast meat. Slaughtering older birds increases myoglobin content in the meat and selection of breeds for greater breast meat yield may be involved. Using a wheat-based diet tends to lighten the colour of breast meat but has less effect on the thigh meat. Several antimicrobials used in further processing can lead to either bleaching or a reddening of the meat. Changes to colour using chemical or physiological methods are theoretically possible, however may not be great enough to improve consumer acceptability. From a marketing perspective, increased media promotion of dark meat as being equal to white meat in healthiness and superior in flavour may have the greatest effect on increasing sales.

The detection, enumeration, and virulence potential of viable but non-culturable (VBNC) pathogens continues to be a topic of discussion. While there is a lack of definitive evidence that VBNC Listeria monocytogenes (Lm) pose a public health risk, recent studies suggest that Lm in its VBNC state remains virulent. VBNC bacteria cannot be enumerated by traditional plating methods, so the results from routine Lm testing may not demonstrate a sample’s true hazard to public health. We suggest that supplementing routine Lm testing methods with methods designed to enumerate VBNC cells may more accurately represent the true level of risk. This review summarizes five methods for enumerating VNBC Lm: Live/Dead BacLight^TM staining, ethidium monoazide and propidium monoazide-stained real-time polymerase chain reaction (EMA- and PMA-PCR), direct viable count (DVC), 5-cyano-2,3-ditolyl tetrazolium chloride-4′,6-diamidino-2-phenylindole (CTC-DAPI) double staining, and carboxy-fluorescein diacetate (CDFA) staining. Of these five supplementary methods, the Live/Dead BacLight^TM staining and CFDA-DVC staining currently appear to be the most accurate for VBNC Lm enumeration. In addition, the impact of the VBNC state on the virulence of Lm is reviewed. Widespread use of these supplemental methods would provide supporting data to identify the conditions under which Lm can revert from its VBNC state into an actively multiplying state and help identify the environmental triggers that can cause Lm to become virulent. Highlights: Rationale for testing for all viable Listeria (Lm) is presented. Routine environmental sampling and plating methods may miss viable Lm cells. An overview and comparison of available VBNC testing methods is given. There is a need for resuscitation techniques to recover Lm from VBNC. A review of testing results for post VBNC virulence is compared