SLICED, VACUUM-PACKED FRANKFURTER-TYPE SAUSAGE - TECHNOLOGICAL MEASURES TO INHIBIT THE GROWTH OF LISTERIAE

During normal commercial storage for 3 to 4 weeks at 7-degrees-C Listeria monocytogenes grew by up to 7 powers of ten on sterilely sliced and vacuum-packed frankfurter-type sausage. In samples obtained from the trade, however, relatively low listeriae counts were often found at the end of the minimum shelf life. It was noted that at this time about 60 % of samples have a lactic acid bacteria count of more than 10(7) CFU/g at pH values between 5.6 and 5.7 32 % of samples however contained fewer than 100 org./g lactic acid bacteria. A noticeable inhibition of the growth of L. monocytogenes of up to 3 powers of ten could be achieved in sliced, vacuum-packed frankfurter-type sausage where there was contamination by at least 10(5) lactic acid bacteria/g during slicing. Inhibition of growth was increased to a maximum of 4 powers of ten by adding 0.1 % sodium acetate to the complete sausage mixture, given the same conditions. Adequate inhibition of Listeria growth, without contaminating flora impairing the sensory quality, was only achieved however when, where 0.1 % sodium acetate was added and contamination with lactic acid bacteria dispensed with, the storage temperature was lowered to at least 5-degrees-C and the storage time reduced to 3 weeks. To avoid the risk of listeriosis from eating sliced, vacuum-packed frankfurter-type sausage it is recommended that these products should have 0.1 % sodium acetate added to them during manufacture should be sliced under conditions that are as sterile as possible, should be stored at a maximum temperature of 5 degrees-C and for a period limited to 3 weeks. Under these conditions it would be possible to introduce the steps envisaged for these products in the catalogue of measures of the BGA where, without enrichment, more than 100 L monocytogenes orgasm are found in the directly streaked material.