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Pol. J. Food Nutr. Sci. 2005;55(Special issue 1s):107–110
Cooked ham is a mild pasteurised meat product originated from hind leg of hog offered sliced and vacuum- or MA-packed for sale. Its shelf life is determined by bacterial flora surviving the cooking process and the contamination during slicing. As such hetero- and homo-fermentative Gram-positive lactic acid bacteria and Brochothrix thermosphacta are the main spoilage microorganisms while the prevailing Gram-negative microflora are Serratia liquifaciens, Hafnia alvei. Nowadays consumers demand high quality and convenient meat products, with natural flavour and taste, and the appearance of fresh processed food. The available strategies for reduction of pathogenic and spoilage bacteria tend to minimise the dosage of traditional preservatives such as sodium or potassium salts of lactic or acetic acid basing on synergistic combinations with other products derived from nature. This research is focused on the bacteriostatic effect of ROBIN® products, a combination of long-chained organic acids of plant origin and traditional preservatives: Na-lactate (SL) and Na-diacetate (SD), against Hafnia alvei, Brochothrix thermosphacta and Listeria innocua. To this end, products of canned cooked ham, after cooking and post-thermal resting (t=24 h, T=1°C), were aseptically sliced, inoculated with known number of particular strain (2 log cfu/g), vacuum-packed and incubated at 4°C for 28 days. First results show satisfactory growth inhibition of all bacteria by ROBIN®. The exception was the first week of incubation in the case of Br. thermosphacta and L. innocua in samples containing product R1, where the difference in growth between the control sample and the mentioned ROBIN® was not clear. The supplementation with SL and SD enhances bactericidal effect, restraining the growth completely. Prolonged shelf life of meat products by extension of bacterial lag phase was also observed in the case of all three groups of micro-organisms. Results of this study show that the dosage of traditional preservatives can be minimised or completely replaced by new products which are natural in origin.