AGGREGATION OF BETA-LACTOGLOBULIN AS A FUNCTION OF PH AND TEMPERATURE

Studies were carried out to evaluate the efficiency of removal of beta -lactoglobulin from cheese whey using biospecific subunit exchange aff inity chromatography (BSEAC). The highest percent recovery (78.28%) wa s achieved at a pH of 4.6. Using hydrophobic interaction chromatograph y (HIC) and particle size distribution (PSD), aggregation phenomena, t he basis for the selective extraction of beta-lactoglobulin, was exami ned. While HIC proved to be inconclusive, a general pattern was obtain ed. PSD is a light scattering technique which can be utilized to deter mine average particle size (nm) suspended in a solution. A distinct pr ofile evolved when particle size was plotted against pH for the two ex perimental temperatures. While beta-lactoglobulin has a tendency to te tramize between pH 3.7 and 5.2, it was observed that the highest degre e of aggregation was at the isoelectric point (pH 5.2). At pH 4.6 the aggregates had an average size of 240 nm while at pH 5.2 the average w as 340 nm (4 degrees C). It was proposed that the separation efficienc y of beta-lactoglobulin could be optimized if: 1) aggregate size was m aximized through pH manipulation (pH 5.2, 4 degrees C) and 2) a suppor t matrix that would accomodate complexes in excess of 340 nm was utili zed.