食品科学 ›› 2020, Vol. 41 ›› Issue (11): 90-96.doi: 10.7506/spkx1002-6630-20190528-337

• 食品工程 • 上一篇    下一篇

不同干燥方式对甘薯叶片水分迁移、微观结构、色泽及复水性能影响的比较

季蕾蕾,木泰华,孙红男   

  1. (中国农业科学院农产品加工研究所,农业农村部农产品加工综合性重点实验室,北京 100193)
  • 出版日期:2020-06-15 发布日期:2020-06-22
  • 基金资助:
    “十三五”国家重点研发计划重点专项(2017YFD0400401)

Comparative Effect of Different Drying Processes on Mass Migration, Microstructure, Color and Rehydration Property of Sweet Potato Leaves

JI Leilei, MU Taihua, SUN Hongnan   

  1. (Key Laboratory of Agro-products Processing, Ministry of Agriculture and Rural Affairs, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193, China)
  • Online:2020-06-15 Published:2020-06-22

摘要: 本实验以新鲜甘薯叶片为原料,采用热风、真空冷冻、微波真空、远红外4 种不同干燥方式分别对其进行干燥,采用低场核磁共振以及干燥曲线揭示干燥过程中甘薯叶片内部的水分状态、分布、含量变化情况,解析干燥过程中甘薯叶片内部传质传热过程,分析干燥后甘薯叶片微观形态、色泽以及复水性能变化综合评价干燥产品的品质。结果表明:甘薯叶片内的水可分为两部分,结合水T21(0.06~13.67 ms)和自由水T22(13.67~580.52 ms),不同干燥方式中微波真空干燥干燥速率最快,0.75 h时水分质量分数即可从鲜叶时的84.42%降为9.97%,且传质和传热方向都是由内至外,干燥后的甘薯叶片表面气孔结构褶皱程度较低,其微观结构未呈现明显变化,亮度最大且色泽最绿,无明显变黄现象,其复水率(6.69±0.29)显著高于远红外干燥(4.92±0.73)(P<0.05),且与真空冷冻干燥、热风干燥得到的甘薯叶片相当。

关键词: 甘薯叶片, 低场核磁共振, 干燥曲线, 微观结构, 复水能力

Abstract: In the present study, fresh sweet potato leaves were by four different drying methods of hot air drying, vacuum freeze drying, microwave vacuum drying and far infrared drying. Low field nuclear magnetic resonance and drying curves were used to evaluate changes in moisture content, state and distribution as well as mass and heat transfer in sweet potato leaves during drying. Besides, comprehensive quality assessment of the dried products was conducted with respect to micromorphology, color and rehydration performance. Results showed that the water in sweet potato leaves was classified into two types: bound water T21 (0.06–13.67 ms) and free water T22 (13.67–580.52 ms). Microwave vacuum drying showed the fastest drying speed, reducing the moisture content from 84.42% to 9.97% in 0.75 h. Both mass and heat transfer occurred from the inside to the outside of sweet potato leaves, and the porous structure in the surface of sweet potato leaves exhibited decreased degree of wrinkling after drying, with no significant change being observed in the microstructure. The microwave vacuum dried product had the highest levels of brightness and green color without obvious yellowing. In addition, its rehydration capacity (6.69 ± 0.29) was equivalent to that of the dried samples obtained by vacuum freezing drying and hot air drying, but significantly higher than that from far infrared drying (4.92 ± 0.73) (P < 0.05).

Key words: sweet potato leaves, low field nuclear magnetic resonance, drying curve, microstructure, rehydration capacity

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