Abstract: [Objective]The milk-derived glycomacropeptide（CGMP） was obtained by enzymatic hydrolysis of cow's milk using rennet.Due to the tolerance difference of CGMP to trichloroacetic acid,the separation and purification of CGMP was realized. The β-casein was separated from the casein hydrolyzed by rennet by the characteristic that β-casein was easily freed under low temperature and low acid conditions.[Method]The defatted fresh milk was fully enzymatically hydrolyzed by adding an appropriate amount of rennet at 35 ℃,and centrifuged to obtain the supernatant and precipitate. Trichloroacetic acid was added to the supernatant to remove the impurities of CGMP,and the purity of the obtained precipitated CGMP was measured by high performance liquid chromatography.The precipitation was redissolved in alkaline and the temperature was lowered.Then the pH value was adjusted to 3.5 under the condition of low temperature throughout the whole process.The supernatant was collected by centrifugation at low temperature.After that,the temperature was raised to 35 ℃ to gain β-casein with centrifugation at room temperature.Its purity was determined by high performance liquid chromatography.[Result]3% trichloroacetic acid could better remove impurities after CGMP enzymatic hydrolysis.CGMP was completely precipitated by 10% trichloroacetic acid.The purity of the final CGMP product was 80% to 90% and the β-casein with treatment of low temperature and low acid had a purity of 85% to 90%.

Key words: CGMP, β-casein, HPLC, separate