麦洼牦牛同中国荷斯坦牛乳的缓冲性能比较

用微量滴定法研究了麦洼牦牛及中国荷斯坦牛脱脂乳的滴定曲线和缓冲容量，两种牛乳的滴定曲线具有类似形状，并且往前和返回滴定的曲线都是不一致的，在ＰＨ：２－１１间总的积分缓冲容量同乳蛋白含量有关，酸化过程中最大缓冲出现在ＰＨ＝４．２－４．８，往回滴定时最大缓冲出现在ＰＨ６．３，但在先碱化后酸化滴定中没有ＰＨ６．３处的缓冲峰，这些差异可能同乳中胶体磷酸钙在滴定中的变化有关。

Compahsons of Buffering Propenies of Milk between Maiwa Yak and Chinese-Holstein

Skim milk of Maiwa yak and Chinese-Holstein were used to detect their buffer capacityby titrating with base or acid.The titration curves uf milk,which were similar in shape in yak andChinese-Holstein,were different determined by titration methods. The total integral buffer capacities ofmilk wIthin the range of pH2.0 to pH11.0 were related to protein concentrations in milk.The highestouffer capacities were at pH4.2 to pH4.8 by addin8 acid first,and at pH6.3 by followed adversetitration. Luwer buffer capacities were observed at pH6.3 when titrating with base first and then withacid.It was suggested that the differences were related to the changes in state of Calcium phosphatate inmilk during titration.