In meat fermented foods, Clostridium spp. growth is kept under control by the addition of nitrite. The growing request of consumers for safer products has led to consider alternative bio-based approaches, the use of protective cultures being one of them. This work is aimed at checking the possibility of using two Lactobacillus spp. strains as protective cultures against Clostridium spp. in pork ground meat for fermented salami preparation. Both Lactobacillus strains displayed anti-clostridia activity in vitro using the spot agar test and after co-culturing them in liquid medium with each Clostridium strain. Only one of them, however, namely L. plantarum PCS20, was capable of effectively surviving in ground meat and of performing anti-microbial activity in carnis in a challenge test where meat was inoculated with the Clostridium strain. Therefore, this work pointed out that protective cultures can be a feasible approach for nitrite reduction in fermented meat products.

In the present work, a combined hurdle approach for fermented meat preservation was investigated. Challenge tests were performed in Chorizo sausage model using the maximum allowed NaNO 2 amount (150mg/kg), a reduced amount (75 mg/kg) and no nitrite, with and without protective cultures inoculation. Cocktail strains of L. monocytogenes and Salmonella spp. were used as indicator strains. In a nitrite reduced sausage model, L. monocytogenes growing trend did not significantly change (p>0.05) when compared with that containing higher nitrite concentration (150 mg/kg NaNO 2). The addition of L. plantarum PSC20 significantly lowered L. monocytogenes growth when compared with control batches without PCS20 (p<0.05), obtaining 3.84 log cfu/g and 2.62 log cfu/g lower counts in the batches with 150mg/kg NaNO 2 and 75mg/kg NaNO 2 respectively. None of the protective cultures demonstrated in situ antagonistic activity against Salmonella spp. This work pointed out that the reduction of nitrites with the combined use of a protective culture could be a feasible approach to control L. monocytogenes growth in fermented meat foods.

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