Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey; Particle and Interfacial Technology Group, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey.
Food Res Int. 2020 Nov;137:109527. doi: 10.1016/j.foodres.2020.109527. Epub 2020 Jul 15.
Double or multiple emulsions have been under study for several decades, due to the possibility of encapsulation and controlled release of various bioactive compounds. This contribution focuses on the decisive parameters for encapsulation and release in double emulsions by considering different amino acids at different environmental conditions. Laser diffraction analysis showed that the double emulsion average droplet size increased from 50 up to 90 µm after 32 days of storage. The emulsions at 4 °C showed a higher increase compared to 37 °C. Dilution in SDS solution revealed that this droplet size increase was due to aggregation rather than coalescence. The results showed that there was no significant change in the entrapped water volume fraction of the double emulsions during 2 weeks of storage. Amino acids were encapsulated within the internal aqueous phase with an efficiency of at least 80%. Regarding the release of the entrapped amino acids, it was found that both the temperature and the hydrophobicity of the amino acid had a significant effect. Fastest release was found at the highest temperature studied (i.e. 37 °C), which was thought to be due to the higher solubility and faster diffusion rate of the amino acid in the oil phase. As hydrophobicity increased, the released amino acid concentration also increased. The pH, on the other hand, did not have a significant effect on the release within the pH range considered (i.e. 7-10). The constant internal water volume fraction, together with the significant effect of temperature and hydrophobicity, indicated that the main release mechanism of amino acids in double emulsions is by direct diffusion from the internal to the external aqueous phase.
双乳液或多重乳液已经研究了几十年，因为它有可能封装和控制各种生物活性化合物的释放。本研究主要关注不同环境条件下不同氨基酸对双乳液封装和释放的决定性参数。激光衍射分析表明，双乳液的平均液滴尺寸在储存 32 天后从 50 增至 90 µm。在 4°C 下，乳液的增加量高于 37°C。在 SDS 溶液中稀释表明，这种粒径的增加是由于聚集而不是聚结。结果表明，在 2 周的储存期内，双乳液的包封水体积分数没有明显变化。氨基酸以内水相的形式被包裹，效率至少为 80%。关于包封氨基酸的释放，发现温度和氨基酸的疏水性都有显著的影响。在研究的最高温度（即 37°C）下，释放最快，这可能是由于氨基酸在油相中的溶解度更高，扩散速度更快。随着疏水性的增加，释放的氨基酸浓度也增加。另一方面，pH 值在考虑的 pH 值范围内（即 7-10）对释放没有显著影响。恒定的内部水体积分数，加上温度和疏水性的显著影响，表明氨基酸在双乳液中的主要释放机制是通过内部直接扩散到外部水相。
