The destruction of enzymes and bacteria during the spray-drying of milk and whey. II. The effect of the drying conditions
Daemen, A.L.H.; Stege, H.J. van der
Netherlands Milk and Dairy Journal 36(3): 211-229
Effects of drying conditions on the destruction of the enzymes and bacteria studied in Part I [DSA 44, 4205] were determined. Outlet air temp. had a marked effect, which was best expressed by a pseudo-z value (the temp. increase needed to obtain a 10-fold increase in destruction). Inlet air temp. had little effect. It was expected that destruction would increase with increases in particle size, but air in the particles masked this effect. Destruction of the bacteria (especially Serratia marcescens) appeared to be due in part to a non-thermal effect; this was confirmed by counting bacteria before and after films of inoculated conc. milk were dried under vacuum at room temp.