GROWTH SUPPRESSION OF LISTERIA-MONOCYTOGENES IN A MEAT PRODUCT

Bologna-type sausages were manufactured using standard industry proces ses and four different formulations: (a) standard commercial formulati on (control), (b) with 2% sodium lactate, (c) with 2% lactate and 0.25 % glucono-delta-lactone (GDL), (d) with 2% lactate and 0.5% GDL. The s liced sausages were inoculated with a mixture of L. monocytogenes sero type 1 and 4 (approximately 100 cfu/g). The samples were vacuum-packag ed and stored at 5 degrees C and 10 degrees C for 35 days. Rapid growt h of L. monocytogenes was observed in control samples stored at 5 degr ees C and in control samples and lactate treated samples (without GDL) stored at 10 degrees C. In sausages containing GDL (both levels) grow th did not occur within 35 days at either 5 degrees C or 10 degrees C. Thus the presence of GDL at low level seemed sufficient to prevent gr owth of L. monocytogenes, although pH in the product was as high as 6. 3. In samples with 2% lactate and without GDL, growth was suppressed f or 28 days at 5 degrees C. Results indicate that it is possible to sup press growth of L. monocytogenes in chilled cooked meat products by us ing suitable amounts of sodium lactate combined with lowering of pH. H owever, when using GDL as a pH lowering agent, off-flavours may be reg istered by some individuals at high levels of GDL.