Moisture sorption isotherms and isosteric heat of sorption of leaves and stems of lemon balm (Melissa officinalis L.) established by dynamic vapor sorption

详细信息	查看全文 | 推荐本文 |

• 作者：Dimitrios Argyropoulos^a ; ^{dimitrios.argyropoulos@uni-hohenheim.de} ; Rainer Alex^b ; Robert Kohler^b ; Joachim Mü ; ller^a
• 关键词：Melissa officinalis L. ; DVS ; Equilibrium moisture content ; Isosteric heat ; Medicinal plants ; Oswin
• 刊名：Lebensmittel-Wissenschaft und -Technologie
• 出版年：2012
• 期刊代码：121_00236438
• 类别：abs
• 出版时间：July, 2012
• 卷：47
• 期：2
• 页码：324-331
• 文件大小：562 K

摘要

The equilibrium moisture contents (MC) of leaves and stems of lemon balm (Melissa officinalis L.) were determined separately at temperatures of 25, 35 and 45聽掳C over a stepwise increase of relative humidity (RH) ranging from 3 to 90%by an automatic, gravimetric analyzer (DVS system). Equilibrium was achieved within 6聽h for most of the target values of relative humidity. The equilibrium moisture content of leaves was significantly higher than that of stems (p聽<聽0.05). Differences in moisture sorption capacity between the leaves and stems can be attributed to chemical composition and structure of the tissues. Five three-parameter moisture sorption models (modifications of Chung-Pfost, GAB, Halsey, Henderson and Oswin) were tested for their effectiveness to fit the experimental sorption data. The modified Oswin equation was found to be the best model to describe the adsorption isotherms of both leaves and stems of lemon balm. The recommended MC values of leaves and stems for microbial safe storage at 25聽掳C were 0.124 and 0.113 kg water per kg dry solids, respectively. The net isosteric heat of sorption was computed from the predicted sorption data by applying the integrated form of the Clausius-Clapeyron equation.