Top Institute Food & Nutrition , P.O.Box 557, 6700AN Wageningen, The Netherlands.
Langmuir. 2012 Apr 24;28(16):6551-60. doi: 10.1021/la300344g. Epub 2012 Apr 15.
Whey protein particles have several applications in modulating food structure and for encapsulation, but there is a lack of methods to prepare particles with a very high internal protein content. In this study whey protein particles with high internal protein content were prepared through emulsification and heat gelation of 25% (w/w) whey protein isolate solution at different pH (6.8 or 5.5) and NaCl concentrations (50, 200, or 400 mM). Particles formed at pH 6.8 were spherical, whereas those formed at pH 5.5 were irregular and had a cauliflower-like appearance. Both particles had an average size of few micrometers, and the particles formed at pH 5.5 had higher protein content (∼39% w/v) than the particles formed at pH 6.8 (∼18% w/v). Similarly, particle morphology and protein density were also affected by initial NaCl concentration: particles formed at 50 mM NaCl (pH 6.8) were spherical, whereas particles formed at either 200 mM NaCl (pH 6.7) or 400 mM NaCl (pH 6.6) were irregular and protein density of the particles increased with increasing initial NaCl concentration. Whey protein particles formed at pH 5.5 showed an excellent heat stability: viscosity of the suspensions containing approximately 30% of protein particles formed at pH 5.5 did not show any change after heating at 90 °C for 30 min while the viscosity of suspensions containing protein particles prepared at other conditions increased after heating. In summary, whey protein particles with varying microstructure, shape, internal protein density, and heat stability can be formed by using heat-induced gelation of whey protein isolate at different gelling conditions.
乳清蛋白颗粒在调节食品结构和封装方面有多种应用，但缺乏制备高内部蛋白质含量颗粒的方法。在这项研究中，通过在不同 pH（6.8 或 5.5）和 NaCl 浓度（50、200 或 400 mM）下对 25%（w/w）乳清蛋白分离物溶液进行乳化和热凝胶化，制备了具有高内部蛋白质含量的乳清蛋白颗粒。在 pH 6.8 下形成的颗粒是球形的，而在 pH 5.5 下形成的颗粒是不规则的，呈菜花状。两种颗粒的平均粒径均为数微米，在 pH 5.5 下形成的颗粒的蛋白质含量（约 39%w/v）高于在 pH 6.8 下形成的颗粒（约 18%w/v）。同样，颗粒形态和蛋白质密度也受到初始 NaCl 浓度的影响：在 50 mM NaCl（pH 6.8）下形成的颗粒是球形的，而在 200 mM NaCl（pH 6.7）或 400 mM NaCl（pH 6.6）下形成的颗粒是不规则的，并且颗粒的蛋白质密度随着初始 NaCl 浓度的增加而增加。在 pH 5.5 下形成的乳清蛋白颗粒具有优异的热稳定性：在 90°C 加热 30 分钟后，含在 pH 5.5 下形成的约 30%蛋白质颗粒的悬浮液的粘度没有任何变化，而在其他条件下制备的含蛋白质颗粒的悬浮液的粘度在加热后增加。总之，通过在不同的凝胶化条件下使用乳清蛋白分离物的热诱导凝胶化，可以形成具有不同微观结构、形状、内部蛋白质密度和热稳定性的乳清蛋白颗粒。
