1 National Food Institute, Technical University of Denmark2 Division of Industrial Food Research, National Food Institute, Technical University of Denmark3 Department of Chemical and Biochemical Engineering, Technical University of Denmark4 CHEC Research Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark5 Computer Aided Process Engineering Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark6 Novozymes A/S7 University of Calabria8 Centre for oil and gas – DTU, Center, Technical University of Denmark
A biochemically structured model has been developed to describe the continuous fermentation of lactose to ethanol by Kluveromyces marxianus and allowed metabolic coefficients to be determined. Anaerobic lactose-limited chemostat fermentations at different dilution rates (0.02 – 0.35 h-1) were performed. Species specific rates of consumption/formation, as well as yield coefficients were determined. Ethanol yield (0.655 C-mol ethanol*C-mol lactose-1) was as high as 98 % of theoretical. The modeling procedure allowed calculation of maintenance coefficients for lactose consumption and ethanol production of ms = 0.6029 and me= 0.4218 (C-mol)*(C-mol*h)-1, respectively. True yield coefficients for biomass, ethanol and glycerol production were calculated to be Ytrue sx = 0.114, Ytrue ex = 0.192 and Ysg = 2.250 (C-mol)*(C-mol)-1, respectively. Model calculated maintenance and true yield coefficients agreed very closely with those determined by regressions of the experimental data. The model developed provides a solid basis for the rational design of optimised fermentation of cheese whey.