Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia.
School of Chemical Engineering, UNSW Sydney, NSW 2052, Australia.
Food Res Int. 2020 Nov;137:109377. doi: 10.1016/j.foodres.2020.109377. Epub 2020 Jun 4.
The blend of fish oil with a high percentage of long chain poly-unsaturated fatty acids, and milkfat with a high percentage of saturated fatty acids, could potentially demonstrate desirable characteristics from both components, such as increased omega-3 fatty acids and melting point, as well as improved crystallization and oxidative stability. In this study, the effect of various milkfat concentrations on thermal properties and crystalline structure of these blends were analysed to understand parameters determining the overall characteristics of the blend. Blends with different ratios of fish oil: milkfat (9:1, 7:3, 5:5, 3:7, 1:9), as well as pure fish oil and pure milkfat, were investigated at different cooling conditions. The crystallization behaviour in all samples shifted to lower temperature ranges, by increasing the cooling rate from 1 to 32 °C/min. However, the changes in cooling rate did not have significant effect on the melting profile of the samples. Whereas changes in milkfat ratio affect both the crystallization and melting behaviour. New crystallization peaks were observed on DSC spectra between the range of -4 to -13 °C in the blends. Moreover, new melting peaks appeared in two ranges of -1 to -8 °C and 8-9 °C, in the blends. The crystallization and melting behaviour of the blends were similar to those of milkfat when >30% milkfat was used. This was further confirmed via XRD where milkfat demonstrated the dominant polymorphic behaviour. Regarding shape of the crystals, fractal dimension analysis showed a similarity between clusters in blends containing 50% milkfat or higher. Increasing the ratio of milkfat led to an increase in fractal dimension which indicates higher mass-spatial distribution of the crystal networks in the blends. The data showed that adding 30% or more milkfat to pure fish oil resulted in blends demonstrating similar characteristics to milkfat, including thermal, structural, and oxidative stability. This shows the potential of blending a high percentage of docosahexaenoic acid in milk fat to improve their overall stability.
鱼油与长链多不饱和脂肪酸的高比例混合，以及乳脂与高比例饱和脂肪酸的混合，可能会表现出两种成分的理想特性，例如增加 ω-3 脂肪酸和熔点，以及改善结晶和氧化稳定性。在这项研究中，分析了不同乳脂浓度对这些混合物热特性和晶体结构的影响，以了解决定混合物整体特性的参数。研究了不同鱼油：乳脂比例（9:1、7:3、5:5、3:7、1:9）的混合物，以及纯鱼油和纯乳脂在不同冷却条件下的情况。所有样品的结晶行为都向更低的温度范围转移，通过将冷却速率从 1 增加到 32°C/min。然而，冷却速率的变化对样品的熔融曲线没有显著影响。而乳脂比例的变化则同时影响结晶和熔融行为。在 DSC 谱中，在 -4 至 -13°C 的范围内观察到新的结晶峰出现在混合物中。此外，在 -1 至 -8°C 和 8-9°C 的范围内，在混合物中出现了新的熔融峰。当使用 >30%的乳脂时，混合物的结晶和熔融行为与乳脂相似。这通过 XRD 进一步得到证实，其中乳脂表现出主导的多晶型行为。关于晶体的形状，分形维数分析表明，在含有 50%或更高乳脂的混合物中，簇之间存在相似性。随着乳脂比例的增加，分形维数增加，这表明混合物中晶体网络的质量空间分布更高。数据表明，向纯鱼油中添加 30%或更多的乳脂可使混合物表现出与乳脂相似的特性，包括热、结构和氧化稳定性。这表明在乳脂中混入高比例的二十二碳六烯酸以提高其整体稳定性具有潜力。
