engleski

The fate of indigenous microbiota during spontaneous fermentation of wild boar (Sus scrofa) and dear (Cervus elaphus) meat sausages produced in Croatia

Three wild boar (WB1, WB2 and WB3) and three dear meat (DS1, DS2, DS3) sausages, produced by five different manufacturers following traditional techniques, were physio-chemically and microbiologically investigated at different time points of their production (0, 4, 7, 10, 20 days and at the end of ripening). The metabolic activity of lactic acid bacteria (LAB), which dominated the fermentation and ripening process, resulted in end products with pH and aw values between 5.04 – 5.53 and 0.83 – 0.87, respectively. Total of 917 isolates were collected from media used for cultivation of LAB (MRS, KAA, MSE and LamVab) and identified to species and strain level by 16S rRNA gene sequencing and rep-PCR. Although commonly used for the isolation of specific groups of LAB, most of the applied media exhibited poor selectivity and supported the growth of diverse genera of LAB or even non LAB species. In total, Leuconostoc mesenteroides was identified as the most frequently isolated species (28.24 %), followed by Lactobacillus sakei (20.72 %) and Enterococcus casseliflavus (11.55 %), however, strong differences were observed in distribution profiles of LAB among investigated sausages. Le. mesenteroides was the predominant species found in WB1, WB2, DS1 and DS2 sausages, while in WB3 and DS3 sausages Lb. sakei was most frequently detected. Cluster analysis revealed strong sausage-specific clustering of strains, indicating meat as a probable source of bacterial strains that established during fermentation, since WB3 and DS1 sausages were produced at the same production unit but rarely shared the strains belonging to the same cluster. The succession of les-acid tolerant, heterofermentative LAB such as Le. mesenteroides with Lactobacillus spp. was observed, most probably as a result of decline in pH values during fermentation. Microbiological anaysis revealed high cell counts of pathogens at the end stage of WB3 and DS2 sausages, making them potentially hazardous for human health. Such results highlight the vast differences between sausage types and indicate the need for exploring the possibilities of product standardization.

spontaneous fermentation: game meat sausages: lactic acid bacteria: rep-PCR: media selectivity

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