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首页> 外文学位 >Ohmic heating of foods: Studies on microbicidal effect of electricity, electrical conductivity of foods, and heat transfer in liquid-particle mixtures.
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Ohmic heating of foods: Studies on microbicidal effect of electricity, electrical conductivity of foods, and heat transfer in liquid-particle mixtures.

机译：食物的欧姆加热：研究电，食物的电导率和液体-颗粒混合物中的热传递的杀微生物作用。

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摘要

A device was developed for conventional or ohmic heating of biomaterials, and modified for electrical conductivity measurement of foods during heating.;Death kinetics of yeast cells were compared under conventional and ohmic heating conditions by subjecting cell suspensions in a phosphate buffer solution to identical time-temperature histories. No significant difference was found in the death rates during conventional and ohmic heating. However, electrical pretreatment studies on Escherichia coli indicated increased inactivation under certain combinations of sublethal electrical pretreatment and conventional heating.;Electrical conductivities of various juices, vegetables, and meats were determined during conventional and ohmic heating. Electrical conductivity of juices increased with temperature and decreased with solids content, and that of solid foods increased linearly with temperature at 60 V/cm. For solid foods, the linearity of conductivity curves during ohmic heating gradually changed when decreasing applied voltage, ending in a non-linear curve for conventional heating. Soaking vegetable tissue in water reduced conductivity, whereas salt solutions increased tissue conductivity as manner dependent on the salt concentration.;A mathematical model based on probability distribution and electrical circuit theory was developed to determine the effective electrical conductivity of liquid-particle mixtures. The results of this and previous models were compared with the experimental values for mixtures of potato cubes and sodium phosphate solutions. Differences between experimental and model results (except for the series model) were within the same range. Conductivities predicted by the probability model were in good agreement below 60;Two heat transfer models, based on different electrical circuit assumptions, were developed for ohmic heating of liquid-particle mixtures in a static heater. Simulated temperatures of liquid and particles were compared with the experimental temperatures obtained for potato cubes and sodium phosphate solutions. The model with a parallel liquid element for the length of the heater predicted reasonable temperatures using low convective heat transfer coefficients. The heating rates of liquid and particles depended on their electrical conductivities, and size and volume fraction of particles.
机译：开发了一种用于常规或欧姆加热生物材料的设备，并对其进行了改进，用于加热过程中食品的电导率测量;通过将磷酸盐缓冲液中的细胞悬浮液置于相同时间下，比较了常规和欧姆加热条件下酵母细胞的死亡动力学温度历史。在常规加热和欧姆加热过程中，死亡率没有显着差异。但是，对大肠杆菌的电预处理研究表明，在亚致死性电预处理和常规加热的某些组合下，灭活增加了。在常规和欧姆加热条件下，测定了各种果汁，蔬菜和肉类的电导率。果汁的电导率随温度升高而降低，随固体含量降低，而固体食品的电导率随温度在60 V / cm时线性增加。对于固体食品，当降低施加的电压时，欧姆加热过程中电导率曲线的线性会逐渐改变，最终以常规加热的非线性曲线结束。将植物组织浸泡在水中会降低电导率，而盐溶液则取决于盐浓度而增加组织电导率。;建立了基于概率分布和电路理论的数学模型，以确定液体-颗粒混合物的有效电导率。将该模型和以前的模型的结果与马铃薯块和磷酸钠溶液混合物的实验值进行比较。实验结果与模型结果之间的差异（系列模型除外）在同一范围内。概率模型预测的电导率在60以下时非常吻合；根据不同的电路假设，开发了两种传热模型，用于在静态加热器中对液体颗粒混合物进行欧姆加热。将液体和颗粒的模拟温度与马铃薯块和磷酸钠溶液的实验温度进行了比较。对于加热器的长度，具有平行液体元素的模型使用低对流传热系数预测了合理的温度。液体和颗粒的加热速率取决于它们的电导率，颗粒的大小和体积分数。

著录项

  • 作者

    Palaniappan, Sevugan.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Agriculture Food Science and Technology.;Engineering Agricultural.
  • 学位 Ph.D.
  • 年度 1991
  • 页码 202 p.
  • 总页数 202
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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