Volatile compounds associated with microbial growth on normal and high pH beef stored at chill temperatures

Volatile metabolites from some gram-negative bacteria

A survey of volatile organic compounds (VOCs) excreted from various Gram-negative bacteria (Pseudomonas spp., Serratia spp. and Enterobacter spp.) was carried out. Compounds were identified by gas chromatography-mass spectrometry. VOCs identified included dimethyl disulphide, dimethyl trisulphide and isoprene.

Bacterial spoilage of meat and cured meat products

The influence of environmental factors (product composition and storage conditions) on the selection, growth rate and metabolic activity of the bacterial flora is presented for meat (pork and beef) and cooked, cured meat products. The predominant bacteria associated with spoilage of refrigerated beef and pork, are Brochothrix thermosphacta, Carnobacterium spp., Enterobacteriaceae, Lactobacillus spp., Leuconostoc spp., Pseudomonas spp. and Shewanella putrefaciens. The main defects in meat are off-odours and off-flavours, but discolouration and gas production also occur. Bacteria associated with the spoilage of refrigerated meat products, causing defects such as sour off-flavours, discolouration, gas production, slime production and decrease in pH, consist of B. thermosphacta, Carnobacterium spp. Luctobacillus spp. Leuconostoc spp. and Weissella spp. Analysis of spoilage as measured by bacterial and chemical indicators is discussed. It is concluded that a multivariate approach based on spectra of chemical compounds, may be helpful in order to analyse spoilage, at least for spoilage caused by lactic acid bacteria. The consequences of bacteria bacteria interactions should be evaluated more.