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首页> 外文学位 >Study of caking in powdered foods using nuclear magnetic resonance (NMR).
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Study of caking in powdered foods using nuclear magnetic resonance (NMR).

机译：使用核磁共振（NMR）研究粉状食品的结块。

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摘要

Twenty-three powdered foods and ingredients and their mixtures were subjected to two treatments: temperature scan from -20 to 110°C within two hours, and storage at 37, 45, 55, and 65°C for 60 days. During temperature scans, the spin-spin relaxation time T2 values of individual samples were determined using a nuclear magnetic resonance (NMR) technique, resulting in a T2-temperature curve for each sample. Four typical T2-temperature curve patterns were identified, and were found to be closely related to the physical changes including partial agglomeration, moisture migration to the surface of particles, and caking that occurred to the samples during temperature scans. Based on the T2-temperature curve patterns, the samples were classified into four groups, each having distinguished caking behavior. The caking behavior of the mixture of two or more ingredients could also be predicted by the T2-temperature curve patterns of individual ingredients. In the storage tests, the samples were removed for tests periodically from the incubators maintained at different temperatures and relative humidities. The storage tests suggest a strong relationship between molecular mobility and caking. Temperature dependence of time until caking was expressed reasonably well by the Arrehnius equation, which can also be used to predict the time until caking. Monitoring changes in T 2 as a function of temperature provides information useful for predicting whether and when caking would occur. Based on the NMR data and the storage tests for single powders and mixtures of several powders, formulation of caking-resistant commercial food products containing more than twenty ingredients would be possible.
机译：对二十三种粉状食品和成分及其混合物进行了两种处理：在两个小时内从-20扫描到110°C的温度，并在37、45、55和65°C的温度下存储60天。在温度扫描期间，使用核磁共振（NMR）技术确定单个样品的自旋-自旋弛豫时间T2值，从而得出每个样品的T2温度曲线。确定了四个典型的T2温度曲线图，发现它们与物理变化密切相关，包括部分团聚，水分迁移到颗粒表面以及温度扫描过程中样品发生结块。基于T2温度曲线图，将样品分为四组，每组具有明显的结块行为。两种或多种成分的混合物的结块行为也可以通过各个成分的T2温度曲线图来预测。在储存测试中，定期从保持在不同温度和相对湿度的培养箱中取出样品进行测试。储藏测试表明分子迁移率和结块之间存在密切关系。 Arrehnius方程可以很好地表示结块之前的时间与温度的关系，该方程还可以用于预测结块之前的时间。监测T 2作为温度的函数的变化提供了有用的信息，可用于预测是否会结块以及何时结块。根据NMR数据和单个粉末以及几种粉末的混合物的储藏测试，可以配制包含超过20种成分的抗结块商业食品。

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  • 作者

    Chung, Myong-Soo.;

  • 作者单位

    University of Minnesota.;

  • 授予单位 University of Minnesota.;
  • 学科 Agriculture Food Science and Technology.; Engineering Agricultural.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 137 p.
  • 总页数 137
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农产品收获、加工及贮藏;农业工程;
  • 关键词

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