The purpose of this study was to determine the efficiency of denitrification process of red beet juice by Paracoccus denitrificans bacteria and culture process influence on sensory properties of juice after fermentation and evaluation of the usefulness of denitrified juice for the production of a natural colouring preparation for foods. The use of P. denitrificans bacteria resulted in complete reduction of nitrates in the juice, at initial nitrate concentration 4 g/l and maximal denitrification rate 0,67 g/l h. In the model investigations the greatest effect on red and yellow pigments loss and their ratio changes as well as changes of colour parameters was demonstrated by oxygen availability and pH value. The microbiological denitrification process influenced on colour and flavour changes. However, concentration by evaporation makes possible to use the juice after denitrification in production of colouring preparation.