| Summary: | The aim of this study was to investigate the effect of long-term cold storage of fermented beetroots and fermented beetroot juice on the content of biologically active compounds and microorganisms. Contents of total phenolics, as well as red and yellow betalains were determined. Total phenolics content in fermented grated beetroot was 920 mg/kg after 7 months of cold storage, while in juice it was 810 mg/L within the same time span. At the end of the experiment, after 10 months of storage, these values decreased to 570 mg/kg and 540 mg/L, respectively. Concentration of red betalains after 7 months of storage was determined at 116 mg/kg for grated beetroot and at 69 mg/L for juice. At the same time, the content of yellow betalains was 14 mg/kg and 19 mg/L for grated beetroot and juice, respectively. In the case of fermented beets and juice, about 3-fold decrease of red pigments was observed during storage. Bioactive compounds were identified using LC-MS. Betanidin was shown to be the major compound among grated beetroot pigments at the beginning of the investigation, the beetroot juice was predominated by isobetanidin and betanidin. At the end of the study, the proportion of pigments changed slightly. Lactic acid bacteria predominated among the bacterial microbiota in the products tested. Enterobacteriaceae were not detected in fermented grated beetroots and investigated juices throughout storage time. To conclude, during long-term cold storage, the content of bioactive compounds decreases, however, remains at a high level.
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