School of Food Science and Engineering, Henan University of Technology.
J Oleo Sci. 2022 Sep 30;71(10):1427-1438. doi: 10.5650/jos.ess22017. Epub 2022 Sep 9.
Blend oils composed by leaf lard (LL) and cottonseed oil stearin (COS) were prepared and the thermal property, microstructure and crystallization of these blends were investigated in the present study. Solid fat content (SFC), thermal behaviors, triacylglycerols composition, crystal structure and morphology of the LL and COS blends were determined by pulsed nuclear magnetic resonance (pNMR), differential scanning calorimetry (DSC), high-performance liquid chromatography (HPLC), X-ray diffractometer (XRD) and polarized light microscope (PLM), respectively. SFC profiles and iso-solid diagrams indicated that SFCs of all blends were almost close to the weighted averages of the fat components at temperatures beyond 20°C; however, below 20°C, SFCs of blends exhibited higher than those of the weighted averages of the fat components. With the content of COS increasing, palmitic acid and linoleic acid in the blends increased, while stearic acid and oleic acid decreased; monounsaturated-disaturated (USS) and triunsaturated (UUU) glycerides in the blends enhanced, while monosaturated-diunsaturated (UUS) glycerides declined. The melting temperature of the blends decreased with the increase of COS content. The crystal forms in LL were β' and β, and the packing pattern was double and triple chain length (2L and 3L). With COS in blends increasing, β' form crystals and 3L pattern reduced. Polarized light micrographs showed that the number of crystal particles in the blends raised with the increase of COS content, meanwhile, the grainsize of the sample gradually decreased. Visual appearances of the blends indicated that blending LL with COS could efficiently reduce the graininess of LL. The addition of COS had a significant effect on the crystallization behavior of LL. LL presented one-step crystallization at 10°C and 20°C, while COS showed two-step crystallization at 10°C and one-step crystallization at 20°C. However, the blends exhibited obvious two-step crystallization at 10°C, one-step or slight two-step crystallization at 20°C.
制备了由猪脂（LL）和棉籽油硬脂（COS）组成的混合油，并研究了这些混合物的热性能、微观结构和结晶性。通过脉冲核磁共振（pNMR）、差示扫描量热法（DSC）、高效液相色谱法（HPLC）、X 射线衍射仪（XRD）和偏光显微镜（PLM）分别测定了猪脂和棉籽油硬脂混合物的固体脂肪含量（SFC）、热行为、三酰基甘油组成、晶体结构和形态。SFC 曲线和等固线图表明，在 20°C 以上温度下，所有混合物的 SFC 几乎接近脂肪成分的加权平均值；然而，在 20°C 以下，混合物的 SFC 高于脂肪成分的加权平均值。随着 COS 含量的增加，混合物中的棕榈酸和亚油酸增加，而硬脂酸和油酸减少；混合物中的单不饱和-双不饱和（USS）和三不饱和（UUU）甘油三酯增加，而单不饱和-双不饱和（UUS）甘油三酯减少。混合物的熔融温度随着 COS 含量的增加而降低。猪脂的晶体形式为β'和β，堆积方式为双链和三链长度（2L 和 3L）。随着混合物中 COS 含量的增加，β'形式的晶体和 3L 模式减少。偏光显微镜照片显示，随着 COS 含量的增加，混合物中晶体颗粒的数量增加，同时样品的晶粒尺寸逐渐减小。混合物的外观表明，将猪脂与 COS 混合可以有效地减小猪脂的颗粒度。COS 的添加对猪脂的结晶行为有显著影响。猪脂在 10°C 和 20°C 下呈现一步结晶，而 COS 在 10°C 下呈现两步结晶，在 20°C 下呈现一步结晶。然而，混合物在 10°C 下表现出明显的两步结晶，在 20°C 下表现出一步或轻微的两步结晶。
