High pressure-induced gel formation of milk and whey concentrates

Gels from milk concentrates [milk and caseinate powder ultrafiltration (UF) and microfiltration (MF)] and whey concentrates (UF) were obtained with high pressure (200 and 400 MPa, 10 and 30 min). The effects of protein concentration (66-114 g kg(-1) for milk and 97-127 g kg(-1): for whey), NaCl addition (0-8 g kg(-1)), sodium citrate addition (0-4 g kg(-1) and pH (5.2-6.6 for milk and 7-9 for whey) were studied with a Box-Behnken design. Milk supplemented with caseinate powder did not lead to gel formation by pressure. For UF or MF mill: concentrates, a pH decrease towards 5.9 and a protein content increase led to firmer pressure-set gels. Gels of whey concentrates were obtained only at pH 9. A pressure increase from 200 to 400 MPa led to firmer gels, while a protein content increase did not. (C) 1998 Elsevier Science Limited. All rights reserved.