Em. Dumay et al., HIGH-PRESSURE UNFOLDING AND AGGREGATION OF BETA-LACTOGLOBULIN AND THEBAROPROTECTIVE EFFECTS OF SUCROSE, Journal of agricultural and food chemistry, 42(9), 1994, pp. 1861-1868
The effects of processing at 450 MPa and 25 degrees C for 15 min on th
e unfolding and aggregation of an industrial beta-lactoglobulin protei
n isolate (beta LG) have been studied at pH 7.0 (at 0.1 MPa) and two p
rotein concentrations, at 0-5% sucrose. After 2.5 or 5% protein soluti
ons (no sucrose) were pressure processed, beta LG remained soluble, bu
t the residual enthalpy of denaturation (Delta H, as determined by DSC
20-27 h after pressurization) was decreased by 44 or 54%, respectivel
y, indicating significant unfolding. Solubility in 2 M ammonium sulfat
e was similarly decreased, evidencing pressure-induced protein aggrega
tion. Some soluble aggregates (36-10(3) kDa) were observed by gel perm
eation chromatography. Pressure-induced unfolding or aggregation (at 2
.5% protein) was found to be partially reversible with storage time af
ter pressurization (up to 26 or 33%, respectively, of the initial chan
ges, after 7 days at 4 degrees C). The presence of 5% sucrose during p
ressurization at 2.5% protein reduced beta LG unfolding (Delta H was d
ecreased by 27% instead of 44%) and slightly increased the rate of rec
overy of protein solubility in 2 M ammonium sulfate.