Immunisation against Lactic-acid Bacteria as a Technique to Extend the Chilled Storage Life of Vacuum-packed Lamb

Forty lambs were immunised against a cocktail of five 'lactic acid' spoilage bacteria typical of those found on vacuum packaged chilled meat. The animals were slaughtered and their hind legs removed within 20 min. Half of the legs (one from each carcass, were inoculated with viable Lactobacillus delbrueckii cells (one of the organisms used in the vaccine formulation), vacuum packaged and stored at - 1.5 C. Forty non-immunised controls were similarly processed and packaged. The vaccine elicited an immune response as determined by ELISA assay. Over a 16-week storage period, meat derived from immunised animals generally returned lower numbers of bacteria than meat derived from non-immunised animals. Sensory analysis determined that non-immunised product stored for longer than 12 weeks had a higher level of undesirable odours and flavours than immunised product. These findings support the view that immunising lambs against spoilage organisms has the potential to extend the storage life of packaged chilled meat.