Chemical, microbial and sensory changes during the anaerobic cold storage of beef inoculated with a homofermentative Lactobacillus sp. or a Leuconostoc sp.

Abstract

Slices of beef were inoculated with about 3.5 log cfu/cm 2 of Lactobacillus sp. 93 SMRICC 235 (homofermentative) or Leuconostoc sp. 89 SMRICC 189 and stored in 5% CO 2 + 95% N 2 at 4°C. The microbial, chemical (glucose, l-lactate, d-lactate, acetate, formate, ethanol, H 2S) and sensory changes of the beef slices were studied. For beef inoculated with Lactobacillus sp. 93 the flavour score started to decrease when the maximum bacterial count was reached. Leuconostoc sp. 89 caused a rapid decrease in the flavour score before reaching the maximum bacterial count. Concentrations of acetate and d-lactate increased while glactose and l-lactate decreased in beef slices inoculated with Lactobacillus sp. 93. In the presence of Leuconostoc sp. 89 ethanol and d-lactate increased while glucose decreased. Lactobacillus sp. 93 formed the highest level of H 2S, and a sulphurous off-odour was noted only in the presence of this strain. d-Lactate and acetate indicated high numbers of Lactobacillus sp. 93 on the meat surface, while d-lactate and ethanol indicated high numbers of Leuconostoc sp. 89. More studies are needed in order to correlate levels of d-lactate, acetate and ethanol with sensory changes.