Optimisation of the glucose feed rate and feed concentration for the production of a recombinant protein (beta-galactosidase) with respect to two different objective functions is addressed in this work. The performance indices optimised were recombinant protein productivity and overall production cost, respectively. The optimisation was based on a model developed and validated independently. The design of a suboptimal feeding policy which is more practical and easier to implement was confirmed experimentally. Sensitivity analyses of the model parameters allowed the effect of disturbances on recombinant protein productivity to be assessed.