Rousseau D, Ghosh S, Park H
Dept. of Chemistry and Biology, Ryerson Univ., Toronto, ON, Canada.
J Food Sci. 2009 Jan-Feb;74(1):E1-7. doi: 10.1111/j.1750-3841.2008.00978.x.
Temperature-induced destabilization of the dispersed phase in butter and margarine was compared by following changes in droplet size (d(3,3)), solid fat content (SFC), and fat crystal spatial organization in the 28-34 degrees C range. At 28 degrees C, both butter and margarine were stable, with similar d(3,3) values (approximately 6 microm) and droplet size distributions. As the storage temperature was raised above 30 degrees C, notable droplet coalescence was observed (for example, at 32 degrees C d(3,3) values of approximately 10 microm for butter and approximately 12 microm for margarine were obtained). Dispersed phase coalescence in butter was dominated by coagulation, with the fat crystal network-limiting droplet-droplet contact until a minimum SFC was reached (approximately 2.5%). In margarine, the rate-limiting step for coalescence was the melting of Pickering crystals present around the dispersed aqueous droplets. Unlike butter, there was no sharp change in stability at a particular temperature or critical SFC. With these differences, coalescence in butter could be modeled as a 2nd-order process and as a 1st-order process in margarine. Overall, these results demonstrated that the kinetic stability of the dispersed aqueous phase in butter and margarine depends on SFC and the spatial distribution of fat crystals within the spreads.
通过跟踪28 - 34摄氏度范围内液滴尺寸（d(3,3)）、固体脂肪含量（SFC）和脂肪晶体空间组织的变化，比较了温度诱导的黄油和人造黄油中分散相的失稳情况。在28摄氏度时，黄油和人造黄油均稳定，具有相似的d(3,3)值（约6微米）和液滴尺寸分布。当储存温度升至30摄氏度以上时，观察到明显的液滴聚并现象（例如，在32摄氏度时，黄油的d(3,3)值约为10微米，人造黄油的约为12微米）。黄油中分散相的聚并主要由凝聚主导，脂肪晶体网络限制液滴与液滴的接触，直到达到最低SFC（约2.5%）。在人造黄油中，聚并的限速步骤是分散水相液滴周围存在的Pickering晶体的熔化。与黄油不同，在特定温度或临界SFC时稳定性没有急剧变化。由于这些差异，黄油中的聚并可模拟为二级过程，而人造黄油中的聚并可模拟为一级过程。总体而言，这些结果表明，黄油和人造黄油中分散水相的动力学稳定性取决于SFC以及涂抹酱中脂肪晶体的空间分布。
