Quality of traditionally produced Istrian sausage and identification of autochthonous lactic acid bacteria strains as potential functional starter cultures

Abstract

Fermented sausages have been manufactured traditionally in the Mediterranean basin. Istrian sausages are one of the many regionally specific products distinguished by the specific traditional recipes and consequentially exceptional sensory characteristics. The aim of this study was to evaluate sensory, physico-chemical and microbiological changes occurring during production and ripening of Istrian sausages made at traditional households, and to compare the results obtained with the identical product produced in industrial conditions. Additional goal was to characterise the autochthonous lactic acid bacteria populations and to obtain the candidate starter strains. Production stages and product ripening parameters could be strictly defined in controlled industrial conditions of the production process, and the results of this study can serve to standardise the production of traditional Istrian sausages. The results from sensory and physico-chemical examination do not show differences in relation to sausages of a similar type investigated in other papers. Lactic acid bacteria were favoured during fermentation at rising salt concentrations, consisting mostly of Lactobacillus strains followed with the abundance of coagulase-negative cocci. Further, we targeted the autochthonous lactic LAB population to select the candidate starter strains for controlled sausage fermentation. Fifty Gram-positive strains with catalase-negative phenotype, rod-shape or cocci morphology, effective acidification kinetics and production of lactic acid identified by sequence analysis of 16S rRNA were considered LAB. The selected LAB strains were able to grow in a range of pH values and high salt concentration important for their metabolic activity during sausage fermentation. According to our results, Lactobacillus sakei, which is a prevalent strain during fermentation of various types of fermented sausages, was frequently detected. Lactobacillus plantarum and Lactobacillus curvatus were also detected in abundance, implying their possible competitiveness among the complex microbial population. Isolated autochthonous strains L. curvatus S30, L. sakei S32 and L. plantarum S50 produced high lactic acid concentrations, tolerated NaCl concentrations present during sausage fermentation, survived at high concentrations of hydrogen ions and inhibited six pathogens associated with contamination of meat products in a strain-specific manner.

Autochthonous Cultures to Improve Safety and Standardize Quality of Traditional Dry Fermented Meats

“…LAB contribute to the safety of dry fermented meats by producing mainly lactic acid from carbohydrates and lowering pH, thus increasing the inhibitory activity of salt and drying towards pathogenic and spoiling microorganisms. L. sakei is the species that predominates in fermented meat products, followed by Lactiplantibacillus plantarum and L. curvatus [ 35 ]. L. sakei is particularly well adapted to the meat ecological niche for its efficient utilization of the substrates available.…”

“…According to the protection rules, for traditional products recipes and manufacturing processes must be followed faithfully, and the possible interventions aimed to ensure safety must be respectful of product sensory characteristics and peculiarities. The role of the LAB and CNS microbiota on overall hygiene is crucial, but safety promotion and technologically relevant characteristics, such as pH lowering capacity, proteolytic activity and pathogen inhibiting capacity, are highly variable among native bacteria [ 35 , 37 ]. Therefore, components of the autochthonous microbiota, adapted to the ecological niches of traditional fermented sausages, must be selected by taking into account both safety assurance and the preservation of sensory distinctness.…”

Autochthonous Cultures to Improve Safety and Stabilize Quality of Traditional Dry Fermented Meats

“…In particular, LAB contribute by lowering pH to the inhibitory activity of salt and drying on the development of pathogenic and spoiling microorganisms [35]. L. sakei is the LAB species most often isolated from fermented meat products and is particularly well adapted to the meat ecological niche because of the capacity to utilize substrates available in the meat matrix.…”

“…According to the protection rules, for traditional products recipes and manufacturing processes must be followed faithfully, and the possible interventions aimed to ensure safety must be respectful of product sensory characteristics and peculiarities. The role of the LAB and CNS microbiota on overall hygiene is crucial but safety promoting and technologically relevant characteristics, such as pH lowering capacity, proteolytic activity, and pathogen inhibiting capacity are highly variable among native bacteria [35,37]. Therefore, components of the autochthonous microbiota, adapted to the ecological niches of traditional fermented sausages, selected according to the above criteria and tested in pilot scale production, could be the best candidates as starters for the stabilization of safety in the respect of product sensory distinctness.…”