engleski

Phenotypic and genotypic characterization of lactic acid bacterial strains for the production of probiotics and functional starter cultures

The aim of this research was isolation and identification of autochthonous lactic acid bacterial strains from Croatian traditional fresh cheeses and characterisation of those strains as probiotics or functional starter cultures that can provide original aroma and texture of autochthonous products. Bacteriocinogenic activity of isolated lactic acid bacteria strains was especially investigated because of its relevance in the inhibition of undesirable microorganisms during the biotechnological production of fermented products and as it is important probiotic property at competition for the nutrients and binding sites in the gastrointestinal tract. Among 15 phenotypically and genotypically characterised lactic acid bacterial strains, two strains with probiotic properties, Enterococcus faecium A7 and Lactobacillus fermentum A8 have been chosen as functional starter cultures for the controlled fresh cheese production from pasteurised milk. For the cheese production, E. faecium A7 and L. fermentum A8 were prepared as dry active cultures by lyophilisation where protective role of cryoprotectors and lyoprotectors (skim milk, glycerol, calcium carbonate, sorbitol, lactose and sucrose) on the strain viability was investigated. The highest viable bacterial cells counts were reached when skim milk was used as lyoprotectant, for the both examined strains. Efficiency of microencapsulation, performed in three different carriers (alginate, κ-carragenan and natrium caseinate), and its impact on the functionality of the selected strains was also investigated. Microencapsulation in alginate has shown the greatest protective role during exposure of the microenacapsulated cells to the simulated gastrointestinal conditions. Fresh cow cheeses, produced by lyophilized microencapsulated cells of E. faecium A7 and L. fermentum A8 have shown sensorial properties similar to traditional one according to flavour, aroma and consistency, with ca 4 x 107 CFU/g of probiotic strains after 10 days of storage.

autochthonous lactic acid bacteria; functional starter culture; identification

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