RESPIRATION QUOTIENT AND YEAST METABOLISM

Authors give an extended explanation and a simple mathematical model o f the change of respiration quotient (RQ) during carbohydrate based ba ker's yeast propagation. On the basis of stoichiometric equations and applying the concept of the equivalents of available electrons, useful and simple expressions were deduced on the relationship of RQ to the overall cell yield. It is a widespread misunderstanding that the highe r the C-incorporation is the lower the RQ will be. On the contrary, th e direction of change and the value of RO depend not only on the C-inc orporation (composition of cells) but on the substrate composition as well. In conclusion, it is shown that RQ is a very informative ferment ation variable but to use it as a control parameter is not as easy as usually thought.