Kinetic modelling of drying and conversion/degradation of isoflavones during infrared drying of soybean

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• 作者：Chalida Niamnuy^a ; ^b ; ^{fengcdni@ku.ac.th} ; Mali Nachaisin^c ; Nattapol Poomsa-ad^c ; Sakamon Devahastin^d
• 关键词：Effective diffusivity ; First-order reaction ; Gas-fired infrared drying ; Inter-conversion and degradation ; Mathematical modelling
• 刊名：Food Chemistry
• 出版年：2012
• 期刊代码：48_03088146
• 类别：abs
• 出版时间：1 August, 2012
• 卷：133
• 期：3
• 页码：946-952
• 文件大小：440 K

摘要

Soy isoflavones, which are well-known for their health benefits, could be affected by the technique and condition that are used to dry soybean prior to its use. In this study the drying kinetics of soybean as well as the inter-conversion and degradation of soy isoflavones during gas-fired infrared combined with hot air vibrating drying (GFIR-HAVD) at various temperatures (50, 70, 130 and 150 掳C) were investigated. Simple kinetic models for the evolutions of both moisture content and isoflavones were proposed and tested. The temperature dependency of the effective moisture diffusivity of soybean could be well described by the Arrhenius correlation with the activation energy of 13.88 kJ/mol. In terms of the evolutions of isoflavones the contents of 6鈥?O-malonylgenistin (MGI) and 6鈥?O-acetylgenistin (AGI) decreased, while genistin (GI) and genistein increased with an increase in the drying temperature and drying time. First-order kinetic models could be used to describe the changes of isoflavones. At all drying temperatures the conversion of MGI to GI exhibited the highest rate constant; this was followed by the conversion of AGI to GI. In addition, MGI had the highest degradation rate constant; this was followed, in descending order, by AGI, GI and GE. The activation energies of degradation were lower than those of inter-conversion among all forms of isoflavones.