A simple nonlinear robust regulator is applied to track a singular optimal reference signal derived for a batch beverage fermentation. The regulator design is based on a model of the process that includes the energy balance and the mass balances of the biomass, ethanol and the sugars involved in the fermentation. Numerical simulations are carried out to show that the nonlinear regulator, computed on the basis of the first approximation of the system, guarantees robust regulation in the presence of parameter variations and model uncertainties.