Abstract: The effects of different pressuization times (5-120 min) and N-ethlmaleimide (NEM,1-10 mmol·L-1) on physicochemical properties of gels induced from 14% (w/v) β-Lactoglobulin (β-Lg) at pH 7.20 under 800 MPa at 30℃ were investigated. The results showed that the hardness and breaking stress of gels were not influenced by increasing pressurization time. The gel showed network structure like honeycomb. The aperture of structure became larger with increasing pressurization time but not broken.The gels kept a high WHC with increasing pressurization time, suggesting that protein-water interaction in gel was not changed significantly during pressurization. The protein solubilized from gels with Tris-Glycine-Na2EDTA buffer or in the same buffer containing 8 mol·L-1 urea and 0.5% SDS decreased with increasing pressurization time. SDS-PAGE patterns were markedly different depending on the presence of β-mercaptoethanol (β-ME). In the absence of β-ME, the bands of dimer, trimer, tetramer and high molecular aggregates were appreciably detected in addition to monomer. In contrast, in the presence of β-ME, only monomer band was detected. The result suggests that disulfide bonding is the primary driving force for gelation under pressurization. Gels were not induced by adding 10 mmol·L-1 N-ethlmaleimide gelation of β-Lg at 800 MPa and the content of sulfhydryl group decreased. It is, therefore, suggested that the formation of gel from β-Lg under pressurization results from intermolecular cross-linkages via oxidation of thiol groups and sulfhydryl-disulfide interchage reactions at neutral pH.

Key words: Hydrostatic pressure, β-Lactoglobulin, N-ethlmaleimide, Physicochemical properties