Spray drying of high pressure jet-processed condensed skim milk

Condensed skim milk (CSM)was high pressure jet (HPJ)processed at 100–500 MPa and then spray dried to obtain skim milk powders (SMP-100 to SMP-500). Physical and instant properties of SMP-100 to SMP-400 were similar to those of the control. However, SMP-500 showed a higher apparent particle density (1.25 g cm⁻³)and a lower solubility (93.2%)compared to the control. A marked increase in foam expansion index (FEI)and foam volume stability index (FVSI)was observed for the reconstituted SMP-400 and SMP-500, with the latter showing a FEI > 110% and a FVSI > 85%, 8 h after foaming. Moreover, emulsions prepared with reconstituted SMP-500 showed a higher emulsion stability index (ESI)compared to other SMPs. The observed differences in interfacial properties of reconstituted SMP-400 and SMP-500 are consistent with HPJ-processed skim milk, which showed extensive pressure- and shear-induced casein micelle modifications.