Proteolytic pattern, antigenicity, and serum immunoglobulin E binding of beta-lactoglobulin hydrolysates obtained by pepsin and high-pressure treatments.

This study evaluates the use of high pressure to enhance pepsin hydrolysis of beta-lactoglobulin (beta-LG). The protein was subjected to high pressure before and during the proteolytic process. Analysis of remnant beta-LG, identification of the peptides produced, and evaluation of antigenicity (binding to commercial antibodies) and binding to IgE of allergic patients' sera were conducted in the hydrolysates. The results showed that the application of high pressure before the enzyme treatment slightly improved the proteolytic process but did not reduce the antigenicity or IgE binding of the hydrolysates. The application of high pressure during the enzymatic treatment enhanced the production of large intermediate fragments that were further proteolysed to smaller fragments as proteolysis proceeded for longer periods. At 400 MPa, all the intact protein was removed in minutes, simultaneously decreasing its antigenicity and serum IgE binding properties. However, for considerable reduction of the antigenicity and IgE binding of beta-LG, extending the incubation time with the enzyme was needed to reduce the amount of potentially allergenic intermediate peptides. Changes of beta-LG under pressure at acidic pH are discussed.