Bacterial mediated off-flavours in retail-ready beef after storage in controlled atmospheres

The effects of anoxic storage under CO2 at 2 degrees C for up to 10 weeks followed by 28 h aerobic display in a retail case on flavour attributes and bacteriology of beef were examined. Pseudomonads reached 2.5 log cfu/cm(2) in one replication only and their numbers decreased with increasing storage time. Enterobacteriaceae and Brochothrix thermosphacta were not above levels of 1.0 and 2.0 log cfu/cm(2), respectively. Presumptive lactic acid bacteria increased to maximum numbers of 5.5 log cfu/cm(2) after 8 weeks. A subpopulation of lactic acid bacteria, able to grow in the presence of 12 g/l acetate, developed later in storage reaching a maximum population of 4.3 log cfu/cm(2). Flavour amplitude dropped to an inappropriate level after 6 weeks. Between 6 and 8 weeks, the numbers of lactic acid bacteria able to grow in the presence of 12 g/l acetate increased in the absence of an increase in presumptive lactic acid bacteria. This time coincided with the development of "off barny" aromatic, "off barny" aftertaste and unidentified "off" aromatic and a reduction in flavour amplitude suggesting a relationship between the growth of these organisms and changes in organoleptic properties. (C) 2000 Elsevier Science Ltd. All rights reserved.