Detection of different microenvironments and Lactobacillus sakei biotypes in Ventricina, a traditional fermented sausage from central Italy

Abstract

The present study evaluated the physico-chemical and microbiological features of Ventricina, considering for the first time the presence of different compartments deriving from the technology of production. In fact meat pieces (pork muscle and fat cut into cubes of about 10-20cm), mixed with other ingredients and then stuffed into pig bladder, are still distinguishable at the end of the ripening. They appear delimited on the outside by the casing and inside by thin layers consisting of spices (mainly red pepper powder), salt and meat juices. Our results showed that the exterior (portion of the product in contact with the casing), the interstice (area between the different cubes of meat or fat) and the heart (the inner portion of meat cubes) had distinctive values of pH and a, and a typical microbial progression, so that they can be considered as different ecological niches, here called microenvironments. The study of lactic acid bacteria population, performed with PCR-DGGE and sequence analysis targeting the V1-V3 region of the 16S rRNA gene (rDNA), highlighted the presence of a few species, including Lactobacillus sakei, Lb. plantarum, Weissella hellenica and Leuconostoc mesenteroides. The RAPD-PCR analysis performed on Lb. sakei, recognised as the predominant species, allowed the differentiation into three biotypes, with that characterised by the highest acidifying and proteolytic activities and the highest ability to grow in the presence of sodium chloride prevailing. This leading biotype, detectable in the interstice during the entire ripening period, was isolated in the microenvironments exterior and heart starting from the 30th d of ripening, and it was the sole biotype present at the end of the ripening. The analysis of microenvironments through the scanning electron microscopy (SEM) evidenced the presence of micro-channels, which could favour the microbial flow from the interstice to the exterior and the heart. Moreover, the SEM analysis allowed the detection of biofilms, recognised as responsible for the correct colonisation of the different meat niches.

Selection of Lactobacillus strains newly isolated from Algerian camel and mare fermented milk for their in vitro probiotic and lipolytic potentials

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Sub-optimal pH Preadaptation Improves the Survival of Lactobacillus plantarum Strains and the Malic Acid Consumption in Wine-Like Medium

“…plantarum as starter in the MLF depends mainly on the strain used, whose metabolic activities are strongly linked to the ability to adapt to the main hurdles of wine (mainly high content of ethanol and low pH). As reported by several Authors (duToit et al, 2011; Tremonte et al, 2017) both ethanol and pH tolerance are strain-dependent features. So, in our study 42 Lb.…”

Pre-cultivation with Selected Prebiotics Enhances the Survival and the Stress Response of Lactobacillus rhamnosus Strains in Simulated Gastrointestinal Transit

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