State Key Laboratory of Food Science and Technology, School of Food Science and Technology, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, People's Republic of China.
School of Food Science and Technology, Shihezi University, Shihezi 832000, Xinjiang, People's Republic of China.
Food Funct. 2019 Sep 1;10(9):5413-5425. doi: 10.1039/c9fo00813f. Epub 2019 Aug 9.
Natural waxes are cost-effective and potential fat crystallization modifiers; however, there is limited information about their implementation in solid triacylglycerol (TAG) oil. Herein, we investigated the effects of two natural waxes, namely, candelilla wax (CLW) and rice bran wax (RW), with different concentrations (2, 4, 6, and 8 wt%) and carbon chains on the crystal growth and structure of palm kernel stearin (PKS85). CLW significantly accelerated the PKS85 crystallization process. Both waxes could induce a new hydrocarbon chain with the lengths of 3.70 and 4.15 Å during the TAG crystallization, respectively. Particularly, X-ray diffraction (XRD) indicated that PKS85 combined with CLW showed a similar lamellar thickness (d) and crystal domain size (ξ) with pure PKS85, whereas that of PKS85 containing RW was 1.7-1.8 and 1.5-1.8 fold higher, respectively. This result corresponded to the carbon chain length of CLW and RW, which was double and quadruple that of PKS85, respectively. Further, these variations were reflected in the crystal microstructures of PKS85 with CLW and RW, where the former showed small homogeneous crystals, while the latter displayed large rod-like layered crystals. In addition, the firmness significantly increased when CLW and RW were added, which is possibly attributed to the fact that the waxes became the backbone of the crystal "fence". Our findings give clear insight into the interaction between TAGs and wax molecules in the crystallization process, which can help guide the utilization of natural waxes in the modification of fats.
天然蜡是一种具有成本效益和潜在脂肪结晶改性作用的物质；然而，关于其在固体三酰基甘油（TAG）油中的应用，相关信息有限。在此，我们研究了两种天然蜡，即小烛树蜡（CLW）和米糠蜡（RW），在不同浓度（2、4、6 和 8wt%）和碳链长度下对棕榈仁硬脂（PKS85）晶体生长和结构的影响。CLW 显著加速了 PKS85 的结晶过程。两种蜡都可以在 TAG 结晶过程中诱导出长度分别为 3.70 和 4.15Å的新碳氢链。特别是，X 射线衍射（XRD）表明，PKS85 与 CLW 结合后表现出与纯 PKS85 相似的层片厚度（d）和晶体畴尺寸（ξ），而与 RW 结合的 PKS85 的层片厚度和晶体畴尺寸分别提高了 1.7-1.8 和 1.5-1.8 倍。这一结果与 CLW 和 RW 的碳链长度相对应，分别是 PKS85 的两倍和四倍。此外，这些变化反映在 PKS85 与 CLW 和 RW 的晶体微观结构中，前者显示出小而均匀的晶体，而后者显示出大的棒状层状晶体。此外，当添加 CLW 和 RW 时，硬度显著增加，这可能是因为蜡成为晶体“栅栏”的骨架。我们的研究结果清楚地揭示了在结晶过程中 TAG 与蜡分子之间的相互作用，这有助于指导天然蜡在脂肪改性中的应用。
