Effect of liquid flow on pigment formation of red beet hairy roots

Red beet hairy roots are cultivated in a single column reactor to investiga te the influence of superficial velocity of medium on formation of betanin (a major pigment component in red beet hairy roots). The betanin content in the cells increases with increasing superficial velocity in the range of 1 3 to 40 m/h, In the cultures at superficial velocities of 15 and 40 m/h for 166 h, the betanin content increases with elapsed time of cultures. The gr owth of the hairy roots is responsible for an increase in shear stress on t he root surfaces By means of lowered void fraction of hairy root hed, and t he estimated values of shear stress range from 0.22 to 188 N/m(2) during bo th the cultures. The activity of monophenol monooxygenase in the cells, whi ch is a key enzyme involved in the biosynthesis of betanin, can be correlat ed with the value of shear stress in such a manner as to approach plateaus gradually with increasing shear stress.