| Abstract [eng] |
The aim of the work was to improve the quality of hard cheeses using pure thermophilic Lactobacillus cultures isolated from cheeses made with spontaneous fermentation, together with usual starters and cultures with antifungal activity. The object of the study was lactic acid bacteria strains isolated from the hard cheeses made from raw milk. Cheese samples (Permigiano Reggiano, Grana Padano, Tete de Moine) were purchased at the supermarket for isolation of thermophilic lactic acid bacteria. 27 lactic acid bacteria cultures were isolated from cheese samples. Microbiological, chemical, biochemical and sensory analysis was accomplished to evaluate their properties. Genetic analysis was accomplished to identify lactic acid bacteria species. Study showed that the properties are typical to Lactobacillus helveticus and Lactobacillus casei. Isolated and selected lactic acid bacteria implied species confirmed pyro-sequencing method by regions of sequences of 16S rDNA gene V1, V2 and V3: 23 cultures assigned to Lactobacillus helveticus, 4 – Lactobacillus casei. 7 Lactobacillus helveticus cultures were selected for further work based on genetic analysis, division of carbohydrates and other earlier results. The manner of forming the starter has been selected for hard cheese producing. The use of Lactobacillus helveticus cultures reduces the number of yeasts as compared to the control cheeses. At the first cheese production number of yeasts decreased from 5,1 ∙102 to 1,1∙102, at the second – from 5,4 ∙102 to 1,0 ∙102. Summarizing the results of sensory analysis showed, that cheeses of the second production were characterized by better sensory properties than cheeses of the first production. However, compared to the control cheese, there were technological defects. Semi-industrial conditions could influence some technological defects of experimental cheeses, as it was not possible to follow strict technological regime. |
