Optimization of brewer's yeast spray drying process

A combination of simulation with experimental treatments of spray drying process were developed in order to minimize the energy resources required to obtain a production of spray dried brewer's yeast at given viability and moisture. The drying was optimized by combining a few affected experiments with a 1.2 m3 spray dryer. Cost function, viability, output moisture and production, were related with process variables, both empirically and by simulation with a non-linear space state reported in literature. Both results were represented with response surface models (RSM). The empirical results state that the optimal operation was at 1 g grits (g yeast solids)−1, 319 s−1, spray rotor velocity, and 60 °C in output air. At these conditions it was obtained 6.86 kg of dried yeast h−1, with a viability of 1.26 × 106 cfu g−1, and 55.5 cost $ kg−1 of product. Simulation results states optimal conditions at initial product moisture of 0.84 g g−1, 214 °C at input air, 202 kg dry air h−1, and 9.56 kg dry product h−1. At these conditions the simulator predicts 10 kg dried yeast per hour with a viability of 1.00 × 106 cfu g−1, and 26.7 cost kg−1 of product.