基于流变和电特性的豆浆凝固过程动力学解析  

Kinetic Model of Coagulation Process of Soymilk Gel Based on Electrical and Rheological Properties

作　　者：熊秀芳[1] 靳莉珍 李星恕[1,2] 郭康权[1,2] 

机构地区：[1]西北农林科技大学机械与电子工程学院,陕西杨凌712100 [2]陕西省农业装备工程技术研究中心,陕西杨凌712100

出　　处：《农业机械学报》2015年第4期211-218,共8页Transactions of the Chinese Society for Agricultural Machinery

基　　金：公益性行业(农业)科研专项资助项目(201003063-07);中央高校基本科研业务费专项基金资助项目(Z109021106;Z109021303)

摘　　要：凝固工序是豆腐生产的关键工序,直接影响豆腐的品质和得率。凝固温度和凝固时间是影响凝固工序的2个关键因素。为了分析凝固温度和时间对豆浆凝固过程的影响,研究了豆浆在凝固过程中流变特性的在线检测方法,采用电阻抗图谱法和动态流变法检测豆浆在凝固过程中电特性和流变特性的变化,建立了不同凝固温度下电特性和流变特性的关系模型。结果表明,电阻抗图谱法和动态流变法均能分析豆浆的凝固过程,其过程由两段一级反应组成且符合连续一级反应模型;第1段反应速率随着温度的增加而增大,是第2段反应速率的10多倍;根据电阻率、弹性模量和黏性模量计算得到活化能分别为17.82、112.90、53.72 k J/mol,表明豆浆在凝固过程中流变特性的变化受温度的影响更大。电特性测量提供了豆浆在凝固过程中流变特性的在线检测方法。To determine the effect of coagulation time and temperature on coagulation process of soymilk and develop a method to online evaluate soymilk gel＇ s qualities nondestructively, electrical impedance spectroscopy （EIS） and rheological measurement （elastic modulus G＇ and viscous modulus G＂） were employed to analyze the coagulation process. Phase angle of soymilk mixture increased drastically at low frequencies and then gradually reached around zero at high frequencies in each tested time course, and 10 kHz was chosen to evaluate soymilk coagulation process as an optimum frequency. Normalized volume resistivity at 10 kHz initially increased sharply and then gradually approached to an equilibrium state for each temperature course. The similar tendency was observed for rheological properties during soymilk coagulation process. Electrical impedance spectroscopy measurement was useful in determination of the endpoint of soymilk coagulation process. The coagulation process of soymilk was divided into two stages which were considered as two successive first-order reactions. The activation energy values calculated by volume resistivity, elastic modulus and viscous modulus were 17.82, 112.90 and 53.72 kJ/mol, respectively. The theological properties were affected more greatly by coagulation temperature than EIS properties. Good agreements between volume resistivity and theological properties were ascertained by the linearity of plot at all coagulation temperatures. Therefore, electrical impedance spectroscopy measurement can provide a method for determining the endpoint of soymilk coagulation process, which was also a simple, fast and reahime approach for monitoring the rheologieal properties of soymilk gel.

关 键 词：豆浆 凝固过程 流变特性 电阻抗图谱 

分 类 号：TS214.2[轻工技术与工程—粮食、油脂及植物蛋白工程]