Analysis of biodenitrification conditions of red beet juice using the response surface method

Microbiological denitrification of red beet juice proceeds under conditions that are unfavorable for pigments. In this study the effects of pH, accessible oxygen, and temperature on the stability of red and yellow pigments were examined. All three factors examined affect the content of pigments. The strongest effects were exerted by pH and oxygen access in red beet juice. An interactive effect of these parameters on losses of red pigments was observed. At increased pH of juice, losses of red pigment were very high, reaching 60-80% at pH 8.0, whereas losses of yellow pigments decreased with an increase of pH. An increase of temperature within the range of 25-30 degrees C did not practically increase losses of pigments and did not influence the color of the juice.