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中国精品科技期刊2020
程新峰,潘玲,李宁,等. 菊芋微波真空干燥过程的水分扩散特性及模型拟合[J]. 食品工业科技,2022,43(6):33−40. doi: 10.13386/j.issn1002-0306.2021070048.
引用本文: 程新峰,潘玲,李宁,等. 菊芋微波真空干燥过程的水分扩散特性及模型拟合[J]. 食品工业科技,2022,43(6):33−40. doi: 10.13386/j.issn1002-0306.2021070048.
CHENG Xinfeng, PAN Ling, LI Ning, et al. Moisture Diffusivity Characteristics and Model Fitting of Jerusalem Artichoke(Helianthus tuberosus L.) during Microwave Vacuum Drying[J]. Science and Technology of Food Industry, 2022, 43(6): 33−40. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2021070048.
Citation: CHENG Xinfeng, PAN Ling, LI Ning, et al. Moisture Diffusivity Characteristics and Model Fitting of Jerusalem Artichoke(Helianthus tuberosus L.) during Microwave Vacuum Drying[J]. Science and Technology of Food Industry, 2022, 43(6): 33−40. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2021070048.

菊芋微波真空干燥过程的水分扩散特性及模型拟合

Moisture Diffusivity Characteristics and Model Fitting of Jerusalem Artichoke(Helianthus tuberosus L.) during Microwave Vacuum Drying

  • 摘要: 为了探究菊芋微波真空干燥过程中水分变化规律,本文考察了不同微波强度对菊芋干燥特性的影响。采用Weibull分布函数和Dincer模型对干燥曲线进行拟合,并结合尺度参数(α)、形状参数(β)、滞后因子(G)、干燥系数(S)等分析了干燥过程的传热、传质机制。结果表明:除1.28 W/g外,菊芋整个干燥过程分为升速、恒速和降速3个阶段,且微波强度越大,最大干燥速率愈高,升速阶段历时越短。β介于1.314~2.175之间,表明干燥过程并非完全由内部扩散主导。G为1.043~1.188,且随微波强度增大而减小。毕渥数(Bi)介于0.179~5.762之间,说明干燥过程物料温度变化由内部导热和边界对流换热共同控制。基于Weibull分布函数、Dincer模型和Fick第二定律得到的水分扩散系数分别为Dcal=5.922×10−8~2.717×10−7 m2/s、Deff=7.570×10−7~1.799×10−5 m2/s、D*eff =2.353×10−9~7.546×10−9 m2/s;同样微波强度下,其大小依次为:Deff>Dcal>D*eff。2.32 W/g下,干燥样品亮度(L*值)最大,为69.05。微波强度愈大,样品色泽参数a*b*值越小。SEM图片显示:适宜的微波强度下,干燥菊芋细胞结构规则,部分区域含有孔洞;1.28 W/g样品的细胞皱缩明显,而高微波强度下(2.70和3.04 W/g)干燥样品部分组织结构坍塌,细胞内物质外泄。

     

    Abstract: To explore the law of moisture variation in Jerusalem artichoke during microwave vacuum drying process, the effects of microwave intensity on the drying characteristics of Jerusalem artichoke were investigated. The Weibull distribution function and Dincer model were used to fit the drying curves, and the heat and mass transfer mechanism during drying process were analyzed by using the model parameters, namely scale parameter (α), shape parameter (β), lag factor (G) and drying coefficient (S). The results showed that there were three stages of rising rate, constant rate and falling rate under all the microwave intensity levels, except for the intensity level of 1.28 W/g. The higher the microwave intensity, the larger the maximum drying rate, and the shorter the duration of rising rate stage. The shape parameter (β) ranged from 1.314 to 2.175, which indicated that the drying process of Jerusalem artichoke was not completely controlled by internal water diffusion. The lag factor (G) ranged from 1.043 to 1.188, and decreased with the microwave intensity increased. The values of Biot number (Bi) located in the range of 0.179 and 5.762, which indicated that the temperature changes of sample in the drying process were controlled by internal thermal conductivity and boundary convective heat transfer. Effective moisture diffusion coefficients calculated by Weibull distribution function, Diner model and Fick’s second law were (Dcal=5.922×10−8~2.717×10−7 m2/s), (Deff =7.570×10−7~1.799×10−5 m2/s), and (D*eff=2.353×10−9~7.546×10−9 m2/s), respectively. Under the same microwave intensity, their values were in order: Deff>Dcal >D*eff. The maximum value of brightness (L*) for dried samples was 69.05 under the microwave intensity level of 2.32 W/g. Both color parameters a* and b* decreased with the increasing of microwave intensities. SEM figures showed that the cell structure in dried Jerusalem artichoke was regular, and exhibited obvious pore characteristics when applying suitable microwave intensity. The tissue structure of dried samples shrank obviously at microwave intensity of 1.28 W/g, while part of the tissue structure collapsed and the intracellular material condensed at higher microwave intensities of 2.70 and 3.04 W/g.

     

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