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 m(3) 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 degreesC in output air. At these conditions it was obtained 6.86 kg of dried yeast h(-1). with a viability of 1.26 x 10(6) cfu g(-1), and 55.5 cost S kg(-1) of product. Simulation results states optimal conditions at initial product moisture of 0.84 g g(-1), 214degreesC at input air, 202 kg dry air h(-1), and 9.56 kg dry product h(-1). At these conditions the predicts 10 kg dried yeast per hour with a viability of 1.00 x 10(6) cfu g(-1), and 26.7 cost kg(-1) of product. (C) 2004 Elsevier Ltd. All rights reserved.