Interfacial properties of acidified skim milk
- 作者：Cases ; E. ; Rampini ; C. ; Cayot ; Ph.
- 关键词：Acidified whole milk ; β ; -Casein ; β ; -Lactoglobulin ; Interfacial properties ; Interfacial tension ; Interfacial viscoelastic modulus
- 刊名：Journal of Colloid and Interface Science
- 出版年：2005
- 期刊代码：125_00219797
- 类别：ch
- 出版时间：February 1, 2005
- 卷：282
- 期：1
- 页码：133-141
- 文件大小：273 K
摘要
The purpose of this study is to investigate the tension properties and dilatational viscoelastic modulus of various skim milk proteins (whole milk, EDTA-treated milk, β-casein, and β-lactoglobulin) at an oil/water interface at 20 °C. Measurements are performed using a dynamic drop tensiometer for 15,000 s. The aqueous bulk phase is a skim milk simulated ultrafiltrate containing Formula Not Shown milk protein. At pH 6.7, β-casein appears as the best to decrease the interfacial tension, whereas β-lactoglobulin leads to the highest interfacial viscoelastic modulus value. Whole milk was almost as surface-active as individual β-casein in terms of the final (steady-state) lowering of the interfacial tension, but the rate of tension lowering was smaller. EDTA treatment improved the rate of tension lowering of whole milk. The acidification of milk, from previous measurements, would lead to the enhancement of surface activity. At Formula Not Shown, the order of effectiveness is pH 4.3 > pH 5.3 = pH 5.6 > pH 6.7 whole milk, suggesting that pH 4.3 whole milk is the best surface active. As compared to pH 6.7 whole milk, the use of pH 5.3 and pH 5.6 milk as surface active would result in the use of milk containing more free β-casein born of pH-dissociated casein micelles.