EFFECT OF THE BINDING OF PALMITIC ACID TO BETA-LACTOGLOBULIN ON ITS GELATION PROPERTIES

The effect of the binding of palmitic acid on gelation properties of 1 0% beta-lactoglobulin in 10 mM phosphate buffer, pH 6.7, was investiga ted by dynamic mechanical spectroscopy. The binding of fatty acids to beta-lactoglobulin has a considerable effect on its gelation propertie s. Fatty acids free beta-lactoglobulin submitted to a linear increase temperature profile had a lower gelation temperature (78 degrees C) th an the protein saturated with palmitic acid (82 degrees C). The storag e modulus (G') after cooling to 20 degrees C was greater for fatty aci ds free beta-lactoglobulin (about 14 kPa) than that obtained with the protein saturated with palmitic acid (about 8 kPa). Isothermal rheolog ical measurements in a temperature range between 70 and 80 degrees C w ere also performed. Results revealed lower gelation time and higher G' values for beta-lactoglobulin without bound fatty acids, differences in both parameters being more pronounced when the temperature was lowe r. Differences in the amount of bound fatty acids could be an importan t source of variability in the gelation behaviour of beta-lactoglobuli n and thus, its control is important if standard gelling properties ne ed to be obtained. (C) 1998 Elsevier Science Ltd. All rights reserved.