Gelling Properties of Heat-Denatured β-Lactoglobulin Aggregates in a High-Salt Buffer

Thermal denaturation, rheological, and microstructural properties of gels prepared from native β-lactoglobulin (β-LG) and preheated or heat-denatured β-LG (HDLG) aggregates were compared. The HDLG was prepared by heating solutions of 4% β-LG in deionized water, pH 7.0, at 80 °C for 30 min and then diluted to the desired concentration in 0.6 M NaCl and 0.05 M phosphate buffer at pH 6.0, 6.5, and 7.0. When reheated to 71 °C, HDLG formed a gel at a concentration of 2% protein. At pH 7.0, 3% HDLG gelled at 52.5 °C and had a storage modulus (G‘) of 2200 Pa after cooling. β-LG (3%) in 0.6 M NaCl and 0.05 M phosphate buffer, pH 7.0, did not gel when heated to 71 °C. The gel point of 3% HDLG decreased by 10.5 °C and the G‘ did not change when the pH was decreased to 6.0. The HDLG gel microstructure was composed of strands and clumps of small globular aggregates in contrast to β-LG gels, which contained a particulate network of compacted globules. The HDLG formed a gel at a lower concentration and lower temperature than β-LG in the high-salt buffer, suggesting an application in meat systems or other food products prepared with salt and processed at temperatures of ≤71 °C. Keywords: β-Lactoglobulin; gelation; microstructure; rheology; denaturation