This work is focused on the study of freeze-thaw behavior of double (W₁/O/W₂) emulsions by the application of a cooling-heating-cooling cycle by differential scanning calorimetry. Emulsions were prepared with sodium caseinate as hydrophilic emulsifier in outer aqueous (W₂) phase and sunflower oil (SO) and/or interesterified vegetable fat (VF) plus polyglycerol polyricinoleate as lipophilic emulsifier in lipid phase. The effects of sodium chloride concentration in inner aqueous (W₁) phase and solid fat content in lipid phase were analyzed. In all cases, W₁ phase froze at lower temperature than W₂ phase because higher undercooling was required for the crystallization of inner water droplets. In the absence of VF, the system with low salt concentration showed water diffusion from undercooled W₁ phase to frozen W₂ phase at the first cooling stage, due to the lower vapor pressure of ice. However, at the second cooling stage, this phenomenon was not observed and partial recovery of inner water was detected, probably because of an osmotic effect. The increase of salt concentration allowed a higher retention of inner water after freezing of W₂ phase, attributed to the lowered vapor pressure of W₁ phase. The loss of inner water was also restrained or prevented by the presence of VF in lipid phase due to the immobilization of water droplets within a fat crystal network. The crystallization behavior of SO was related to inner water quantity and VF content. This study could be useful for the formulation of W₁/O/W₂ emulsions with enhanced freeze-thaw stability.

这项工作致力于通过差示扫描量热法的冷却-加热-冷却循环的应用来研究双（W ₁ / O / W ₂）乳液的冻融行为。用酪蛋白酸钠作为外水相（W ₂）的亲水性乳化剂和葵花籽油（SO）和/或酯化植物脂肪（VF）加聚甘油聚蓖麻油酸酯作为脂相的亲脂性乳化剂来制备乳液。分析了内部水相（W ₁）中氯化钠浓度和脂质相中固体脂肪含量的影响。在所有情况下，W ₁相的冻结温度均低于W ₂因为内部水滴的结晶需要更高的过冷度。在没有VF的情况下，由于冰的蒸汽压较低，低盐浓度的系统在第一冷却阶段显示水从过冷的W ₁相扩散到冷冻的W ₂相。但是，在第二冷却阶段，未观察到此现象，并且检测到内部水的部分回收，这可能是由于渗透作用。盐浓度的增加允许W ₂相冻结后内部水的保留更高，这归因于W _1的蒸气压降低相。由于水滴在脂肪晶体网络中的固定化，脂质相中存在VF也可以抑制或防止内部水分的流失。SO的结晶行为与内部水量和VF含量有关。该研究对于配制具有增强的冻融稳定性的W ₁ / O / W ₂乳液可能是有用的。