Freeze- or spray-dried gluten hydrolysates. 1. Biochemical and emulsifyingproperties as a function of drying process

The biochemical and emulsifying properties of two gluten hydrolysates with an equal degree of hydrolysis (1.4%) produced with the same protease but di ffering in the drying process were studied. The drying processes were freez e-drying for LS2 and spray-drying for PS2. The drying process induced no mo dification of molecular size distribution, hydrophobicity and solubility of gluten hydrolysates. Nevertheless, the emulsifying properties of LS2 dispe rsions were greater than those of PS2 dispersions. Analysis of flocculation -creaming properties and resistance to coalescence of emulsions formed with soluble fractions from these dispersions showed that the difference betwee n the emulsifying properties of LS2 and PS2 could be attributed to the diff ering behaviour of the insoluble fraction as a function of the drying proce ss. Analysis of adsorbed peptides at the oil/water interface confirmed that the interfacial properties of soluble peptides from freeze- and spray-drie d samples were equivalent. (C) 2001 Elsevier Science Ltd. All rights reserv ed.