Department of Agricultural, Environmental and Food Sciences (DiAAA) and Center for Colloid and Surface Science (CSGI), Università degli Studi del Molise, Via De Sanctis, I-86100 Campobasso, Italy.
Department of Agricultural, Environmental and Food Sciences (DiAAA) and Center for Colloid and Surface Science (CSGI), Università degli Studi del Molise, Via De Sanctis, I-86100 Campobasso, Italy.
Colloids Surf B Biointerfaces. 2018 Aug 1;168:163-168. doi: 10.1016/j.colsurfb.2018.02.003. Epub 2018 Feb 5.
In the present investigation the properties of edible nanoemulsions were studied. Sodium caseinate represents a good candidate for food emulsion preparations thanks to its surface-active properties and because it is perceived as a natural product by consumers. Nevertheless, it is very sensitive to acidic pH close to its isoelectric point and, if used as emulsion stabilizer, this aspect can negatively affect the emulsion stability. In order to prevent this drawback, sodium caseinate was used in combination with a non-ionic surfactant (Tween 20) as emulsifier of oil/water nanoemulsions. For these reasons, nanoemulsions stabilized by Tween 20, sodium caseinate and by a blend of the two emulsifiers were studied and compared according to their response to pH variations. Nanoemulsions were characterized for size of the dispersed phase with variation of time and temperature, for their rheological properties, for surface charge as a function of pH and for protein fluorescence. Noticeably, it was ascertained that, at pH close to caseinate isoelectric point, emulsions stabilized with the blend of caseinate and Tween 20 were more stable, compared with emulsions stabilized only with sodium caseinate. Such behavior was explained according to the composition of the emulsifiers at the oil/water interface where, at acidic pH, the presence of Tween 20 ensured the steric stabilization thus improving the role of sodium caseinate as emulsion stabilizer.
在本研究中，研究了可食用纳米乳液的性质。由于其表面活性特性以及被消费者视为天然产品，因此酪蛋白酸钠是食品乳液制备的良好候选物。然而，它对接近等电点的酸性 pH 非常敏感，如果用作乳化剂，这会对乳液稳定性产生负面影响。为了防止这种缺陷，酪蛋白酸钠与非离子表面活性剂（吐温 20）结合使用，作为油/水纳米乳液的乳化剂。由于这些原因，研究并比较了由吐温 20、酪蛋白酸钠以及两者乳化剂的混合物稳定的纳米乳液，根据它们对 pH 值变化的响应进行比较。纳米乳液的特性包括分散相随时间和温度的变化的大小、流变性质、pH 值下的表面电荷以及蛋白质荧光。值得注意的是，在接近酪蛋白等电点的 pH 值下，与仅用酪蛋白酸钠稳定的乳液相比，用酪蛋白酸钠和吐温 20 的混合物稳定的乳液更稳定。这种行为根据油/水界面处乳化剂的组成进行了解释，在酸性 pH 值下，吐温 20 的存在确保了空间稳定作用，从而提高了酪蛋白酸钠作为乳化剂的稳定性。
