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Mathematical modeling of thermal processes: Effects on food safety and starch.

机译：热过程的数学模型：对食品安全和淀粉的影响。

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摘要

Unavoidable process temperature deviations in retort operations can compromise product safety and quality as well as production efficiency if improperly handled. Two methods, the Fixed Point (FP) and the Worst Case (WC) methods, aimed to automatically correct the adverse effect of those process temperature deviations during thermal processes in the operations of continuous retorts were developed. These methods have the potential to quickly analyze and accurately estimate the effect of process deviations on the thermal lethality of canned foods processed in continuous retorts. The FP algorithm consists of the selection of a point that for convenience is located close to the retort steam chamber exit, whereas the WC algorithm consists of searching for the worst case container, defined as the one requiring the lowest conveyor speed. Simulations showed that the computation time for estimating conveyor speed adjustments using both algorithms was less than 1 second in a personal desktop Pentium IV computer.; Accurate heat transfer calculations are the basis for developing suitable control algorithms. The Apparent Position Numerical Solution (APNS) method, which was used in the control algorithms developed in this study, did not provide a good temperature prediction in the initial stage of the process cooling phase. A mathematical method was developed to fix this problem. Heat transfer calculations using numerical methods rely on accurate heat penetration parameters. For thermal processes of starch based food systems, which exhibit a broken-line heating behavior, the heating parameters are strongly associated to the viscosity changes during the heating stage. Major factors affecting the viscosity of swollen crosslinked corn starch (CCS) suspensions were identified and a mathematical model to estimate changes of viscosity was developed in this study. A method to predict the momentary granule sizes, which are closely related to viscosity of a starch suspension, under non-isothermal conditions was also developed. Accurate evaluation of thermal lethality is essential for thermal process design and control. The Weibull model provides a better estimation of process lethality than conventional first-order kinetics. A numerical method suitable for on-line estimation of thermal lethality under non-isothermal conditions was also developed in this study.
机译：如果操作不当，在蒸煮操作中不可避免的过程温度偏差会损害产品安全性和质量以及生产效率。开发了两种方法，定点（FP）和最坏情况（WC）方法，旨在自动纠正连续脱水缸在热加工过程中过程温度偏差的不利影响。这些方法有可能快速分析和准确估计工艺偏差对连续蒸煮罐头食品热致死性的影响。 FP算法包括选择一个点，为方便起见，该点位于靠近脱水缸的出口处，而WC算法包括搜索最坏情况的容器，该容器定义为需要最低输送速度的容器。仿真表明，在个人台式机奔腾IV计算机上，使用这两种算法估算输送机速度调整的计算时间少于1秒。准确的传热计算是开发合适的控制算法的基础。在本研究开发的控制算法中使用的视在位置数值解法（APNS）方法在过程冷却阶段的初始阶段无法提供良好的温度预测。开发了一种数学方法来解决此问题。使用数值方法进行的传热计算依赖于准确的热渗透参数。对于表现出折线加热行为的基于淀粉的食品系统的热处理，加热参数与加热阶段的粘度变化密切相关。确定了影响溶胀的交联玉米淀粉（CCS）悬浮液粘度的主要因素，并开发了估算粘度变化的数学模型。还开发了一种在非等温条件下预测与淀粉悬浮液粘度密切相关的瞬时粒度的方法。准确评估热杀伤力对于热过程设计和控制至关重要。与传统的一阶动力学相比，Weibull模型可以更好地估计过程致死率。本研究还开发了一种适用于非等温条件下热致死率在线估计的数值方法。

著录项

  • 作者

    Chen, Guibing.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Agriculture Food Science and Technology.; Engineering Agricultural.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 207 p.
  • 总页数 207
  • 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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