Comparison of glycomacropeptide isolated from raw and pasteurized goat milk

This study was undertaken to compare K-casein glycomacropeptide (GMP) isolated from raw and pasteurized goat milk using chemical analysis and sodium dodecyl sulfate (SDS) gel electrophoresis. Chemical composition of GMP-depleted whey fraction obtained after isolation of GMP from sweet whey was also determined. The quantitative analytical data except for calcium concentration were similar among the purified GMP samples prepared from the raw and pasteurized milk. The calcium concentration was lower in GMP from pasteurized milk compared to that from raw milk. Gel electrophoresis of GMP demonstrated that pasteurization generates GMP aggregates with increased mobility on SDS gels, and that the low temperature long time (63.5degreesC for 30 min) compared to high temperature short time (72degreesC for 15 s) pasteurization is more effective to induce this change. Studies of the GMP-depleted whey fraction suggest that this product with low threonine content is useful as an ingredient for infant formulas.