Properties and stability of oil-in-water emulsions stabilized by coconut skim milk proteins
Properties and stability of oil-in-water emulsions stabilized by coconut skim milk proteins
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DOI：
10.1021/jf050312r
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发表时间：
2005-07-13
影响因子：
6.1
通讯作者：
McClements, DJ
中科院分区：
文献类型：
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作者：
Onsaard, E;Vittayanont, M;McClements, DJ
从椰子中分离蛋白质级分：椰子脱脂乳蛋白分离物（CSPI）和椰子脱脂乳蛋白浓缩物（CSPC）。将这些蛋白质形成和稳定水包油乳液的能力与乳清蛋白分离物（WPI）的能力进行比较。蛋白质在CSPI、CSPC和WPI中的溶解度在含有0、100和200 mM NaCl（pH 3至8）的水溶液中测定。在不存在盐的情况下，CSPI和CSPC的最小蛋白溶解度发生在pH 4和5之间，WPI的最小蛋白溶解度发生在pH 5左右。在盐（100和200 mM NaCl）的存在下，所有蛋白质具有比在蒸馏水中更高的溶解度。可以使用0.2wt%蛋白质级分生产具有相对小的液滴直径（对于CSPI、CSPC和WPI，d（32）分别类似于0.46、1.0和0.5 μ m）的水包玉米油乳液（10wt%）。用不同的pH值（3-8）、盐浓度（0-500 mM NaCl）和热处理（30-90 ℃，30 min）制备乳液，并测量平均粒径、粒度分布、zeta电位和乳状液分层稳定性。在接近蛋白质的等电点的乳液中发生相当大的液滴絮凝：CSPI，pH类似于4.0; CSPC，pH类似于4.5; WPI，pH类似于4.8。CSPI和WPI在pH 7下可产生具有单峰粒度分布、小的平均液滴直径和良好的乳状液分层稳定性的乳液，而CSPC产生双峰分布。CSPI和WPI乳液在NaCl浓度为100 mg/L时对液滴聚集和乳状液分层保持相对稳定。
Protein fractions were isolated from coconut: coconut skim milk protein isolate (CSPI) and coconut skim milk protein concentrate (CSPC). The ability of these proteins to form and stabilize oil-in-water emulsions was compared with that of whey protein isolate (WPI). The solubility of the proteins in CSPI, CSPC, and WPI was determined in aqueous solutions containing 0, 100, and 200 mM NaCl from pH 3 to 8. In the absence of salt, the minimum protein solubility occurred between pH 4 and 5 for CSPI and CSPC and around pH 5 for WPI. In the presence of salt (100 and 200 mM NaCl), all proteins had a higher solubility than in distilled water. Corn oil-in-water emulsions (10 wt %) with relatively small droplet diameters (d(32) similar to 0.46, 1.0, and 0.5 mu m for CSPI, CSPC, and WPI, respectively) could be produced using 0.2 wt % protein fraction. Emulsions were prepared with different pH values (3-8), salt concentrations (0-500 mM NaCl), and thermal treatments (30-90 degrees C for 30 min), and the mean particle diameter, particle size distribution, zeta-potential, and creaming stability were measured. Considerable droplet flocculation occurred in the emulsions near the isoelectric point of the proteins: CSPI, pH similar to 4.0; CSPC, pH similar to 4.5; WPI, pH similar to 4.8. Emulsions with monomodal particle size distributions, small mean droplet diameters, and good creaming stability could be produced at pH 7 for CSPI and WPI, whereas CSPC produced bimodal distributions. The CSPI and WPI emulsions remained relatively stable to droplet aggregation and creaming at NaCl concentrations of