University of Vigo, Chemistry Faculty, Dept. of Physical-Chemistry, 36310 Vigo, Spain.
University of Vigo, Chemistry Faculty, Dept. of Physical-Chemistry, 36310 Vigo, Spain; REQUIMTE-LAQV, University of Porto, Science Faculty, Dept. of Chemistry and Biochemistry, 4169-007 Porto, Portugal.
J Colloid Interface Sci. 2019 Nov 1;555:224-233. doi: 10.1016/j.jcis.2019.07.085. Epub 2019 Jul 29.
The distribution of antioxidants (AOs) in O/W emulsions depends on two partition constants, that between oil-interfacial (P), and that between the aqueous-interfacial (P) regions, that need to be determined in the unbroken emulsion to prevent disruptions of the present equilibria. Prediction of the effects of temperature on AO partitioning is challenging because may change both P and P in a different extent and the control of their interfacial concentrations is crucial to optimize their antioxidant efficiency. Such effects can be analyzed in the intact emulsions with the aid of a pseudophase kinetic model.
Here we estimated the partition constants of the food-grade antioxidants -propyl (PG), octyl (OG) and lauryl (LG) gallates- in intact corn oil-in-water emulsions and their interfacial concentrations by employing a kinetic methods, and carried out a thermodynamic analysis of the transfer parameters controlling their partitioning.
Results show that the Gibbs free energy for the transfer of gallates to the interfacial region is spontaneous and the transfer process is enthalpy driven. An increase in T favors their incorporation into the interfacial region in an extent that depends on AO hydrophobicity. For any of AOs, the effective interfacial concentrations are much higher (15-170 fold) than the stoichiometric concentration. Results are basic to get a deeper knowledge on the driving force that partitions the AOs in lipid-based foods and to select the best AO to minimize the oxidation of lipids.
抗氧化剂 (AO) 在 O/W 乳液中的分布取决于两个分配常数，即油-界面 (P) 之间和水-界面 (P) 之间的分配常数，需要在未破裂的乳液中确定，以防止现有平衡被破坏。预测温度对 AO 分配的影响具有挑战性，因为它可能在不同程度上改变 P 和 P，并且控制它们的界面浓度对于优化其抗氧化效率至关重要。这种影响可以通过伪相动力学模型在完整乳液中进行分析。
在这里，我们通过动力学方法估计了食品级抗氧化剂 - 丙基 (PG)、辛基 (OG) 和月桂基 (LG) 没食子酸酯 - 在完整玉米油/水乳液中的分配常数及其界面浓度，并对控制其分配的传递参数进行了热力学分析。
结果表明，没食子酸酯向界面区域的转移的吉布斯自由能是自发的，转移过程是焓驱动的。T 的增加有利于它们以依赖于 AO 疏水性的程度掺入界面区域。对于任何 AO，有效界面浓度都要高得多（15-170 倍）于化学计量浓度。结果对于深入了解将 AO 分配在基于脂质的食品中的驱动力以及选择最佳 AO 以最小化脂质氧化具有重要意义。
