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This study evaluated the effect of a ‘formulation of selected dairy starter cultures and commercial probiotics’, associated with ‘specific ripening conditions’ in the production of nitrite and nitrate-free, low-acid, fermented pork sausage, produced in a small-scale plant in Umbria (Italy), and their effect on microbiological, physico-chemical and sensorial properties of the products. The following conditions were investigated throughout the experiment: (i) the use of the ‘formulation of selected dairy starter cultures and commercial probiotics’ vs no starter; (ii) the use of ‘specific ripening conditions’ vs ‘classic ripening conditions’; (iii) the use of nitrate vs nitrite and nitrate-free sausages. Sensory properties were improved and pathogen control was greater in salami to which a ‘formulation of selected dairy starter cultures and commercial probiotics’ had been added, especially under ‘specific ripening conditions’. The proposed formulation, together with the specific ripening conditions, greatly inhibited the growth of undesirable microbiota, reduced the isolation rate of pathogens and preserved the acceptability of the salami.

Several growth curves for selected pathogens and hygiene indicators alone and vs selected dairy starter cultures (LAB) and commercial probiotics have been performed. All strains for LAB and commercial probiotics were inoculated as pure cultures into skim milk to get an initial cocci:bacilli:enterocci ratio of 2:1:1 and a concentration of approximately 107 cfu mL–1 until challenge vs selected pathogens and hygiene indicators. Selected pathogens came from the collection of the Laboratorio di Ispezione degli Alimenti di O.A. or were reference strains (Escherichia coli, CSH26 K12, Staphylococcus aureus 27R, Salmonella Derby 27, Pseudomonas fluorescens ATCC 13525, Listeria innocua ATCC 33090). Each strain was inoculated into skim milk to get an initial concentration of approximately 106 cfu mL–1. Growth curves in skim milk for the following challenges were studied: i) sterility control; ii) association LAB; iii) association of LAB vs each selected pathogen or hygiene indicator; iv) selected pathogen or hygiene indicator alone. The challenges were carried out in BHI broth and in skim milk at 37°C. The highest reduction was observed in milk but in general the association of LAB and the probiotic was able to limit the growth of pathogens and hygiene indicators.