Izco J M, Ordóñez A I, Torre P, Barcina Y
Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, Pamplona, Spain.
J Chromatogr A. 1999 Feb 5;832(1-2):239-46. doi: 10.1016/s0021-9673(98)00965-0.
Recent investigations have shown that capillary electrophoresis (CE) can be an alternative to other techniques such as polyacrylamide gel electrophoresis (PAGE) or sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the qualitative analysis and separation of the different casein fractions in cow's and ewe's milk. However, past work has not yet clarified whether that method can achieve good quantifications. The present study has used a commercial whole ovine casein standard and a mixture of the standard and whole casein extracted from ewe's milk cheese to test the reliability of the technique. The results show that CE was able to quantify the ewe's milk caseins. The areas under four of the most representative peaks on the electrophoretogram for two alpha and two beta-caseins (designated alpha-casein1CE, alpha-casein2CE, beta-casein1CE, and beta-casein2CE in order of elution) were used to validate the method. In relation to linearity, coefficient of determination (r2) values greater than 99% were obtained for the regressions of each of the caseins. Moreover, each casein yielded response factors with a relative standard deviation (R.S.D.) of less than or equal to 5. The coefficients obtained in the day-to-day reproducibility analysis were higher than those for the same-day repeatability, but all the values were within acceptable limits. In the study of accuracy, the percentage recovery rates for the alpha-casein fractions were higher than those for the beta-casein fractions, hence quantification of the latter using this technique would appear to be more accurate under the conditions employed.
最近的研究表明，在对牛奶和羊奶中不同酪蛋白组分进行定性分析和分离时，毛细管电泳（CE）可以替代其他技术，如聚丙烯酰胺凝胶电泳（PAGE）或十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）。然而，过去的工作尚未阐明该方法是否能够实现良好的定量分析。本研究使用了市售的全羊酪蛋白标准品以及从羊奶奶酪中提取的标准品与全酪蛋白的混合物，以测试该技术的可靠性。结果表明，CE能够对羊奶酪蛋白进行定量分析。电泳图上四个最具代表性的峰（两种α-酪蛋白和两种β-酪蛋白，按洗脱顺序分别命名为α-酪蛋白1CE、α-酪蛋白2CE、β-酪蛋白1CE和β-酪蛋白2CE）下的面积用于验证该方法。在线性方面，每种酪蛋白的回归分析获得的决定系数（r2）值均大于99%。此外，每种酪蛋白产生的响应因子的相对标准偏差（R.S.D.）小于或等于5。日常重现性分析中获得的系数高于同一天的重复性系数，但所有值均在可接受范围内。在准确性研究中，α-酪蛋白组分的回收率高于β-酪蛋白组分，因此在所用条件下，使用该技术对后者进行定量分析似乎更准确。
