• Fed-batch fermentations involve controlled feeding of a growth limiting nutrient to a batch culture enabling higher cell densities. Some classic fed-batch strategies employ pH, OUR (oxygen uptake rate), DO (Dissolved oxygen) etc, as control parameters, based on their indirect correlations with growth. This indirect feedback control could lead to an un-optimized process with compromised productivity.
  • FT-NIR spectroscopy is an analytical tool that uses electromagnetic spectrum (~800 – 2500 nm) to cause vibrational energy changes in matter resulting from fluctuations in molecular dipole moment and provides a response that can be used to quantify composition of the material.
  • The FT-NIR probe can penetrate much farther into a medium allowing instant measurements, and little to no sample preparation. However, its meaningful implementation as a standard practice requires vigorous optimization.
  • In this study, we present direct online monitoring of cell density, substrate and product profiles using a single FT-NIR (Fourier Transform Near Infrared) probe during yeast fermentation. This online measurement can then be used to directly control fed batch fermentations, resulting in a precisely optimized process.