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首页> 外文会议>American Oil Chemists' Society Conference on Crystallization and Solidification Properties of Lipids 2000 Toronto, Canada >Ultrasonic Characterization of Lipid Crystallization
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Ultrasonic Characterization of Lipid Crystallization

机译：脂质结晶的超声表征

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摘要

Food oils are mixtures comprised of a range of structurally similar triacylglycerol molecules with differing fatty acid substituents along with several other types of dissolved molecules (1). Because of the range of mutually soluble materials present in the melt, fats can have a range of solid-to-liquid ratios, depending on the composition, current environment, and history of the sample. The solid fat content is a crucial factor, determining various aspects of quality in many foods. While the details of crystallization are dealt with elsewhere in this volume and in the literature (1), it is important to note that, in many cases, there is no way to adequately predict the solid fat content of an unknown sample. Therefore a range of analytical methods has been developed capable of measuring the solids content of an oil mixture. The earliest developed and frequently most precise technique is dilatometry. In this method the changes in volume on freezing of a fixed amount of oil is used to measure solid fat content. The equipment costs of a dilatometric method are relatively modest, but the experiments are often laborious and messy. Dilatometry remains a recommended method (Cd10-57) of the American Oil Chemists' Society (2) but has been largely replaced by various nuclear magnetic resonance methods (AOCS methods Cd 16-81 and Cdl6b-93). Nuclear magnetic resonance (NMR) exploits the differences in nuclear decay time of hydrogen nuclei in the solid and liquid phases. "Solid" nuclei decay in the order of a few ms while "liquid" remains can be polarized for several 100 ms. By making measurements at different times after the excitation pulse, it is possible to distinguish and quantitate the solid/liquid ratio. NMR is a true measure of solid fat content, whereas dilatometry is a relative method that provides only a related solid fat index. NMR instruments are frequently very expensive, but the experiments are easier than dilatometry and many samples can be rapidly measured on a single machine. Solid fat content can also be measured by differential scanning calorimetry (3), but this is not a standard method of the AOCS.
机译：食用油是由一系列结构相似的，具有不同脂肪酸取代基的三酰基甘油分子以及几种其他类型的溶解分子组成的混合物（1）。由于熔体中存在互溶性物质的范围，因此脂肪的固液比可能会有所不同，这取决于成分，当前环境和样品的历史记录。固体脂肪含量是决定许多食品质量各个方面的关键因素。尽管结晶的细节已在本卷的其他地方和文献中讨论过（1），但重要的是要注意，在许多情况下，无法充分预测未知样品的固体脂肪含量。因此，已经开发了能够测量油混合物的固体含量的一系列分析方法。最早发展且通常最精确的技术是膨胀法。在这种方法中，冻结固定量油的体积变化用于测量固体脂肪含量。膨胀法的设备成本相对适中，但是实验通常很费力且麻烦。膨胀分析法仍然是美国石油化学家协会（2）的推荐方法（Cd10-57），但已被各种核磁共振方法（AOCS方法Cd 16-81和Cdl6b-93）取代。核磁共振（NMR）利用固相和液相中氢核的核衰变时间差异。 “固态”原子核的衰减约为几毫秒，而“液态”残留物可以极化几百毫秒。通过在激发脉冲之后的不同时间进行测量，可以区分和定量固液比。 NMR是对固体脂肪含量的真实测量，而膨胀计是仅提供相关固体脂肪指数的相对方法。 NMR仪器通常非常昂贵，但是实验比膨胀法更容易，并且可以在一台机器上快速测量许多样品。固体脂肪含量也可以通过差示扫描量热法（3）进行测量，但这不是AOCS的标准方法。

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