Investigation into the Propagation of Baker's Yeast: A Laboratory Experiment in Biochemical Engineering


  • Xuemei Li The University of Auckland
  • Xiao Dong Chen The University of Auckland
  • Matthew T. Hardin The University of Auckland


A laboratory experiment in biochemical engineering was designed to introduce the concepts related to biocatalysts and bioreactors to chemical engineering students who lack any prior exposure to biology.  The production process of baker's yeast involving multistage scale-up was demonstrated. From the propagation of yeast cells in a 3L bioreactor for 4 or 5 hours, students obtained generally good results of typical microorganisms growth curves as well as glucose consumption, pH, and dissolved oxygen curves corresponding to the growth pattern. The oxygen demand by a given amount of yeast was also estimated.

Author Biographies

Xuemei Li, The University of Auckland

Grace X.M. Li is a postdoc research fellow and a part-time tutor at the Chemical and Materials Engineering Department, the University of Auckland. She is a biochemical engineer with expertise in enzymatic reactions, enzyme immobilization technology, and probiotic bacteria deactivation during drying.

Xiao Dong Chen, The University of Auckland

Xiao Dong Chen is a professor and fellow of the Royal Society of New Zealand, Fellow of the Institution of Chemical Engineers, and a member of AIChE. His main teaching areas are heat and mass transfer, food process engineering, and bioprocessing. His main research areas include freeze concentration, drying, fouling, cleaning, and separation.

Matthew T. Hardin, The University of Auckland

Matt Hardin is now a lecturer at the Division of Chemical Engineering, University of Queensland. He teaches undergraduate lab courses as well as bioprocessing. His research interests include ethanol and  carbohydratederived fuels and plastics and value adding of food processing wastes.