Diffusion Coefficient of Liquid Foods in the Drying Process

液态食品在干燥过程中的扩散系数

• 批准号: 60550669
• 负责人: SANO Yuji
• 金额: $ 0.83万
• 依托单位: Yamaguchi University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550669/
• 关键词: Diffusion coefficient; Water activity; Food; Sugars; Spray drying; Drop; 乾燥特性

In the analysis of the spray drying process of liquid foods, the knowledge of the water diffusion coefficient D and the water activity <a_w> is required. The purpose of this study is to establish a method for predicting the drying behavior of liquid foods on the basis of the D and <a_w> data.The diffusion coefficient of water D in many liquid foods decreases sharply with decreasing water concentration by a factor of several orders of magnitude. We first obtained the numerical solution of the diffusion equation in the shrinking coordinate by using various types of concentration dependence of D. Then, the relation among the integral averaged diffusion coefficient, the drying rate and the ratio of average concentration to the center concentration of the drying specimen was established, by which D can be obtained from the measured drying(desorption) rate, as the function of water concentration.We first applied this method to the isothermal drying experiment with sugars of various molecular weights(glucose, sucrose, oligosaccharose and maltodextrins). The <a_w> data were also measured for these sugars. The diffusion coefficient at infinite dilution <D_0> can be correlated to the molecular weight using the Wilke's diffusion factor. The concentration dependence of D of sugars, D/ <D_0> , can be presented by a single equation regardless of the molecular weight. Similarly, the concentration dependence of the activation energy of D for these sugars was not markedly varied and can be expressed by a single equation.The drying behavior of proteins(bovine serum albumin), liquid foods(skimmilk) and model foods (composed of lactose, casein, albumin and sodium chloride) were examined by using the drying experiment of single droplets. It was found that the drying of these samples was accelerated by the non-uniform shrinkage of the drop and can be predicted well by the numerically calculated drying behavior with the D and <a_w> data of sucrose.

在分析液体食品的喷雾干燥过程中，需要了解水分扩散系数D和水分活度<a_w>。本研究的目的是建立一种方法来预测液体食品的干燥行为的基础上的D和<a_w>数据。水的扩散系数D在许多液体食品中急剧下降，由几个数量级的因子的水浓度降低。本文首先利用D的各种浓度依赖性，在收缩坐标系下得到了扩散方程的数值解。建立了干燥试样的积分平均扩散系数与干燥速率、平均浓度与中心浓度之比之间的关系，并由此得到干燥试样的D值本文首次将这种方法应用于不同分子量的糖的等温干燥实验（葡萄糖、蔗糖、低聚糖和麦芽糖糊精）。还<a_w>测量了这些糖的数据。无限稀释时的扩散系数<D_0>可以使用Wilke扩散因子与分子量相关。糖的D的浓度依赖性，D/<D_0>，可以由一个单一的方程，而不管分子量。同样，D对这些糖的活化能的浓度依赖性变化不大，可以用一个单一的方程来表示。通过单液滴干燥实验，考察了蛋白质（牛血清白蛋白）、液体食品（脱脂乳）和模型食品（由乳糖、酪蛋白、白蛋白和氯化钠组成）的干燥行为。结果发现，这些样品的干燥被加速的不均匀收缩的下降，可以很好地预测的数值计算的干燥行为与D和<a_w>数据的蔗糖。

项目成果

Shuichi YAMAMOTO: Proceeding of World Congress【II】L of Chemical Engineering(Tokyo)MYU Research. Vol.【II】. 564-567 (1986)

Shuichi YAMAMOTO：化学工程世界大会论文集（东京）MYU 研究卷 564-567（1986 年）。

Yuji SANO and Shuichi Yamamoto: "Calculation method of concentration dependent mutual diffusion coefficient based on the assumption of similar concentration distribution" "Drying '86", ed. by A.S.Mujumdar, Hemisphere. I. 85-93 (1986)

Yuji SANO 和 Shuichi Yamamoto：“基于相似浓度分布假设的浓度相关互扩散系数的计算方法”“Drying 86”，编辑。

Shuichi YAMAMOTO and Yuji SANO: "Drying behavior of liquid foods containing various sugars" Proceeding of World Congress III of Chemical Engineering(Tokyo). II. 564-567 (1986)

Shuichi YAMAMOTO 和 Yuji SANO：“含有各种糖的液体食品的干燥行为”第三届世界化学工程大会论文集（东京）。

Yuji SANO,ed.by A.S.Mujumdar,Hemisphere: "Drying'86". 【I】. 85-93 (1986)

Yuji SANO，A.S. 编辑，《半球》：“Drying86”（1986 年）。

山本修一: 粉体工学会誌.

Shuichi Yamamoto：《粉末工程学会杂志》。