Research on the Emulsifying Properties of Diacylglycerol

本文研究了二酰基甘油（DAG）与三酰基甘油（TAG）在分子结构上的不同。基础实验体系：以油相体积分数（φ）为0.5的蛋黄水溶液为实验对象，考察了蛋黄水溶液浓度、pH、NaCl对1:1油相体积分数的影响。pH值对DAG界面张力的影响小于TAG。虽然pH对乳液的平均粒径没有影响，但pH为6时制备的DAG乳液具有较高的粘度。NaCl的加入降低了DAG乳液的界面张力，显著增加了乳液体积。模拟蛋黄酱乳液体系：以1:1蛋黄：3.5%醋酸水溶液为水相，φ为0.7:1，对盐的浓度和种类（NaCl, KCl, CaCl_2, MgCl_2, MgSO_4）的加入，每种盐的加入都降低了乳液的平均粒径，增加了乳液的粘度。特别是在DAG中加入少量的NaCl，大大提高了乳状液的粘度。2)在蛋黄高密度和低密度部分中，高密度部分对DAG的乳化性略有利。低密度部分对DAG无效，而以蛋黄为乳化剂制备的类似蛋黄酱的浓缩乳液有效地发挥了蛋黄的乳化能力，得到的DAG乳液比TAG乳液粒径更小，粘度更高。3)在制备过程中，DAG乳状液的粘度变化，在φ为0.55以上粘度大于TAG，特别是在φ为0.6以上粘度迅速增大。此外，在φ为0.6时，DAG中油滴界面上吸附的蛋白质比TAG中更多。

The present study was conducted to elucidate the emulsion characteristics of diacylglycerol (DAG), which differs in molecular structure from triacylglycerol (TAG), a common lipid.1. Basic experimental system : The effects of aqueous egg yolk concentration, pH, and NaCl addition on 1:1 oil : aqueous egg yolk solutions with an oil phase volume fraction (φ) of 0.5 were tested. The effect of pH on interfacial tension was smaller for DAG than TAG. Although pH had no effect on the mean particle diameter of the emulsions, the DAG emulsion prepared at pH 6 had high viscosity. The addition of NaCl to the DAG emulsion decreased interfacial tension and significantly increased emulsion volume.2. Simulated-Mayonnaise emulsion systems: The following were tested in emulsions with 1 : 1 egg yolk : 3.5% acetic acid solution in aqueous phase with φ of 0.7: 1) For concentration and type of salt (NaCl, KCl, CaCl_2, MgCl_2, MgSO_4), the addition of each salt decreased mean particle diameter and increased viscosity for all emulsions. In particular, addition of small amounts of NaCl to DAG greatly increased the viscosity of the emulsions. 2) Of high-density and low-density fractions of egg yolk, emulsifiability of the high-density fraction was slightly favorable for DAG. While the low-density fraction was found to be ineffective for DAG, a mayonnaise-like concentrated emulsion prepared using egg yolk as the emulsifier effectively demonstrated the emulsifying ability of egg yolk and produced DAG emulsions with smaller particle diameter and higher viscosity than for TAG emulsions. 3) Regarding changes in the viscosity of DAG emulsions during the preparation process, viscosity became greater than that of TAG above φ of 0.55, and in particular, rapidly increased above φ of 0.6. In addition, more protein was adsorbed to the oil droplet interface in DAG than in TAG emulsions at φ of 0.6.