ACID TREATMENT AND PASTEURIZATION AFFECT THE SHELF-LIFE AND SPOILAGE ECOLOGY OF VACUUM-PACKAGED VIENNA SAUSAGES

Vacuum-packaged Vienna sausages, treated by a combination of in-packag e pasteurization and surface application of an organic-acid cocktail, were compared with untreated controls and samples that were only paste urized or acid treated. Total aerobic bacteria, lactic acid bacteria, Enterobacteriaceae and yeasts were quantified by replicate plate count ing of duplicate samples stored at 8 degrees C, and 425 predominant co lonies were isolated and characterized. Microbiological shelf life was set at 5x 10(6) cfu g(-1). Acid treatment decreased shelf life 1 . 8- fold while a c. four-fold increase in shelf life was noted for pasteur ized and combined pasteurized and acid-treated samples. Populations of non-lactic acid bacteria consisted predominantly of Bacillus isolates , especially in pasteurized samples. The relative predominance of non- lactic acid bacteria increased to >44% of isolates in pasteurized samp les. Lactic acid bacteria were the predominant group in samples of all treatments and populations consisted predominantly of homofermentativ e lactobacilli in control and acid-treated samples, whereas pediococci and leuconostocs showed increased predominance in pasteurized samples . (C) 1996 Academic Press Limited.