TY - JOUR

T1 - Reduction of immunoreactivity of bovine β-lactoglobulin upon combined physical and proteolytic treatment

AU - Bonomi, Francesco

AU - Fiocchi, Alessandro

AU - Frøkiær, Hanne

AU - Gaiaschi, Antonella

AU - Iametti, Stefania

AU - Poiesi, Claudio

AU - Rasmussen, Patrizia

AU - Restani, Patrizia

AU - Rovere, Pierpaolo

PY - 2003/2

Y1 - 2003/2

N2 - Bovine β-lactoglobulin was hydrolyzed with trypsin or chymotrypsin before, during and after treatment at 600 MPa and pH 6.8 for 10 min at 30, 37 and 44°C. The extent of β-lactoglobulin hydrolysis under pressure was noticeably higher than at atmospheric pressure, particularly when chymotrypsin was used. Addition of proteases at ambient pressure to previously pressure-treated β-lactoglobulin gave only a modest increase in proteolysis with respect to the untreated protein. Products of enzyme hydrolysis under pressure were separated by reverse-phase HPLC, and were found to be different from those obtained at atmospheric pressure when chymotrypsin was used. The residual immunochemical reactivity of the products of combined pressure-enzyme treatment was assessed on the unresolved hydrolysates by ELISA tests using polyclonal and monoclonal antibodies, and on individual hydrolytic fractions by Western Blotting using sera of paediatric patients allergic to whey proteins in cow milk. The immunoreactivity of the whole hydrolysates was related to their content of residual intact β-lactoglobulin, and no immunochemical reactivity was found for all the products of chymotrypsin hydrolysis under pressure. The results indicate that chymotrypsin effectively hydrolysed hydrophobic regions of β-lactoglobulin that were transiently exposed during the pressure treatments and that were not accessible in the native protein or in the protein that had been previously pressure treated.

AB - Bovine β-lactoglobulin was hydrolyzed with trypsin or chymotrypsin before, during and after treatment at 600 MPa and pH 6.8 for 10 min at 30, 37 and 44°C. The extent of β-lactoglobulin hydrolysis under pressure was noticeably higher than at atmospheric pressure, particularly when chymotrypsin was used. Addition of proteases at ambient pressure to previously pressure-treated β-lactoglobulin gave only a modest increase in proteolysis with respect to the untreated protein. Products of enzyme hydrolysis under pressure were separated by reverse-phase HPLC, and were found to be different from those obtained at atmospheric pressure when chymotrypsin was used. The residual immunochemical reactivity of the products of combined pressure-enzyme treatment was assessed on the unresolved hydrolysates by ELISA tests using polyclonal and monoclonal antibodies, and on individual hydrolytic fractions by Western Blotting using sera of paediatric patients allergic to whey proteins in cow milk. The immunoreactivity of the whole hydrolysates was related to their content of residual intact β-lactoglobulin, and no immunochemical reactivity was found for all the products of chymotrypsin hydrolysis under pressure. The results indicate that chymotrypsin effectively hydrolysed hydrophobic regions of β-lactoglobulin that were transiently exposed during the pressure treatments and that were not accessible in the native protein or in the protein that had been previously pressure treated.

KW - β-lactoglobulin

KW - High-pressure

KW - Protein immunoreactivity

KW - Proteolytic enzymes

UR - http://www.scopus.com/inward/record.url?scp=0037326966&partnerID=8YFLogxK

U2 - 10.1017/S0022029902005678

DO - 10.1017/S0022029902005678

M3 - Journal article

C2 - 12617393

AN - SCOPUS:0037326966

VL - 70

SP - 51

EP - 59

JO - Journal of Dairy Research

JF - Journal of Dairy Research

SN - 0022-0299

IS - 1

ER -