Observability and observers for baker's yeast growth with coordinated uptake of glucose and ammonium

Abstract

This paper investigates the observability of a baker's yeast growth model, which considers the coordinated uptake of glucose and ammonium and includes the overflow metabolism specific to yeast cultures. The observability analysis is performed based on the existence of canonical forms, which is the most employed method for bioprocesses and the results are interpreted based on the condition number of the observability matrix. Two state observers are implemented, an Extended Kalman Filter and a High Gain Observer, to reconstruct the full system state from the available measurements. Simulation results are presented for two scenarios: i) biomass, glucose and ethanol concentrations are measured; ii) only biomass concentration is measured. Only for the first scenario uniform observability could be established with the employed method. Nevertheless, in both scenarios, similar estimates of all system states were provided by both observers.