Abstract: Casein phosphopeptides(CPPs)are the exclusive biological active peptides that can increase the absorption of calcium.Japan and Garmany governments has recommended CPPs for important functional food additives.The active center of CPPs is －SerP－SerP－SerP－Glu－Glu－,so CPPs are a series of short peptides which contain the cluster of phosphoseryl.It was reported that high performance capillary zone electrophoresis(HPCE)and HPLC were used for the qualitative analysis of CPPs.However,these methods need a great deal of money and not easy to manipulate.These methods could not be widely applied to analyze CPPs.In this experiment,there were three methods:quantifying phosphorus of CPPs directly;SDS－polyacrylamid gel electrophoresis(SDS－PAGE)and isoelectric focusing(IEF).The results showed that the three methods were applicable for different situations.The first method could be suitable to measuring CPPs for product control.The other two could be used for research work and phosphopeptide constitute analysis.The IEF method is more exact than SDS－PAGE.Through PAGE and IEF,the concentration and types of CPPs could be determined.

Key words: Casein phosphopeptides Qualitative measuring method SDS－PAGE IEF