Application
Feed based on real-time substrate measurements — not a fixed profile
In fed-batch operation the correct feed rate depends on the substrate concentration and the growth rate in real time. Sampling every few hours means steering a process with a multi-hour lag on a variable that moves in twenty minutes — so operators run conservatively and leave yield on the table on every good batch.
What is tracked
Substrate
Glucose, glycerol or whichever carbon source drives the process. The primary control variable.
Product
The titre curve — productivity, and the point at which it stalls.
By-products
Acetate, lactate or ethanol depending on the system. The earliest signal that the metabolic state has shifted.
The water problem, and what makes it tractable
Broth is mostly water, and water absorbs strongly in the mid-infrared. The analyte bands sit on a large, temperature-dependent background, and the broth also contains cells that scatter. Three things make the measurement work: an optical path matched to the concentration range so the background does not saturate the detector, temperature compensation, and a multivariate model trained on real broth rather than on clean standards.
The instrument is the straightforward part. Building a calibration that holds across strains, feedstock lots and the full concentration range is the actual project — see chemometric model development.
Running fed-batch on a clock?
Tell us the organism, the carbon source and the concentration ranges you need to resolve.