| 不同预处理对铁皮石斛热风干燥特性及品质的影响 |
| |
| 引用本文： | 魏明,张倩,钱森和,赵世光,王晖,杨梦婷.不同预处理对铁皮石斛热风干燥特性及品质的影响[J].农业工程学报,2022,38(8):281-287. |
| |
| 作者姓名： | 魏明 张倩 钱森和 赵世光 王晖 杨梦婷 |
| |
| 作者单位： | 1. 安徽工程大学生物与食品工程学院，芜湖 241000;2. 安徽师范大学生命科学学院，芜湖 241000 |
| |
| 基金项目： | 安徽省高校自然科学研究项目（KJ2019A0143）； 安徽省协同创新项目(GXXT-2019-043)；安徽省科技重大专项（202203a06020029） |
| |
| 摘 要： | 为了优化铁皮石斛干燥工艺，降低其品质劣变风险，对热风干燥前的铁皮石斛鲜条进行直接剪切、烫漂和冻融预处理。研究不同预处理条件的铁皮石斛干燥特性和品质变化；利用低场核磁共振技术分析预处理对铁皮石斛干燥过程中水分迁移的影响。结果表明，预处理是影响铁皮石斛热风干燥过程的重要因素。与直接剪切相比，烫漂和冻融预处理提高了水分有效扩散系数，缩短了干燥时间，降低了能耗，尤以冻融预处理最为显著，干燥时间缩短了44.4%，能耗降低了42.76%（P<0.05）。微观结构观察表明，烫漂和冻融预处理使铁皮石斛组织间隙变大，细胞壁受到破坏，减弱了铁皮石斛组织对水分的束缚并增强了水分流动性，引起水分的重新分布，有利于水分迁移。低场核磁共振技术分析显示，干燥过程中去除的主要是自由水，烫漂和冻融预处理均降低了自由水的脱除时间，冻融预处理去除自由水的时间最少，为120 min。与直接剪切相比，冻融预处理提高了铁皮石斛干品中多糖和多酚的含量，分别提高了10.66%和12.32%，而烫漂预处理降低了铁皮石斛多糖和多酚的含量，分别降低了11.73%和14.73%，3种预处理铁皮石斛生物碱含量差异不显著（P>0.05）。总之，冻融预处理方法可以降低铁皮石斛干燥品质劣变风险，研究结果为石斛加工规范化生产提供参考。
|
| 关 键 词： | 干燥 品质控制 铁皮石斛 预处理 干燥特性 低场核磁共振 |
| 收稿时间： | 2021/10/20 0:00:00 |
| 修稿时间： | 2022/3/30 0:00:00 |
Effects of different pretreatment methods on the hot-air drying characteristics and quality of Dendrobium officinale stems |
| |
| Wei Ming,Zhang Qian,Qian Senhe,Zhao Shiguang,Wang Hui,Yang Mengting.Effects of different pretreatment methods on the hot-air drying characteristics and quality of Dendrobium officinale stems[J].Transactions of the Chinese Society of Agricultural Engineering,2022,38(8):281-287. |
| |
| Authors: | Wei Ming Zhang Qian Qian Senhe Zhao Shiguang Wang Hui Yang Mengting |
| |
| Institution: | 1. College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu 241000, China;;2. College of Life Sciences, Anhui Normal University, Wuhu 241000, China |
| |
| Abstract: | Abstract: Dendrobium officinale has been one of the most precious medicinal plants in China. The functions of antioxidant, antitumor, and immune can be attributed to the biologically active components in the plant, including polysaccharides, polyphenols, and dendrobine. The quality of Dendrobium officinale is prone to deteriorate during storage, due mainly to the stems rich in the water content. Therefore, the dried Dendrobium officinale stems can often inhibit the reproduction of spoilage microorganisms and chemical degradation. The present study aims to optimize the drying process for the high quality of dried Dendrobium officinale stems. A systematic investigation was also implemented to clarify the effect of directly cutting, blanching, and freeze-thaw cycles on the drying characteristics and quality of dried Dendrobium officinale stems. The water mobility and distribution were characterized using 1H Low-Field Nuclear Magnetic Resonance (LF-NMR) and Magnetic Resonance Imaging (MRI) techniques. The results indicated that the pretreatments played an important role in the drying process of Dendrobium officinale stems. Compared with the directly shearing, the blanching and freeze-thaw cycle treatments were beneficial to enhance the effective water diffusion coefficient for the less consumption of energy, and thereby speeding up the drying process. Especially, the freeze-thaw cycle treatment was more effective to improve the drying rate, where the drying time and energy consumption were reduced by 44.4% and 42.76% (P<0.05), respectively. The LF-NMR results showed that there were still three states of water in the stems of Dendrobium officinale. Free water accounted for the largest proportion, followed by the non-flowing water, and the bound water was the least. The MRI images indicated that the moisture on the surface of Dendrobium officinale stems was first removed in the drying process, and then the internal moisture migrated to the surface for evaporation. Scanning Electron Microscopy (SEM) images showed that the intercellular space of dehydrated Dendrobium officinale slices increased, and the cell wall was damaged after blanching and freeze-thaw pretreatments, leading to the changes in water fluidity and distribution for the accelerated migration and removal of water during drying. In the drying characteristics, the free water was removed first in the drying process. Both blanching and freeze-thaw cycle pretreatments were used to reduce the removal time of free water. The freeze-thaw cycle pretreatment took the shortest time (120 min) to remove the free water. It showed that the freeze-thaw cycle greatly contributed to weakening the binding of tissue structure to water for the better fluidity of water. The MRI found that the brightness area of Dendrobium officinale slices decreased with the extension of drying time, whereas, the red gradually decreased, indicating the decrease in water during drying. The freeze-thaw cycle pretreatment was led to the higher retention of polysaccharides and polyphenols in Dendrobium officinale stems, which increased by 10.66% and 12.32%, respectively, whereas, the blanching pretreatment was led to the lower retention of polysaccharides and polyphenols in Dendrobium officinale stems, which was reduced by 11.73% and 14.73%, respectively, compared with the directly shearing during drying. The three pretreatments had no significant effect on the content of dendrobine, which were 1.03, 1.01, and 1.02 mg/g, respectively (P>0.05). In a word, the freeze-thaw cycle pretreatment performed better to speed up the drying process for the high quality of dried Dendrobium officinale stems. The finding can provide the experimental reference to optimize the drying process of Dendrobium officinale stems, further reducing the risk of quality deterioration for the standardization of primary processing of Dendrobium officinale. |
| |
| Keywords: | drying quality control Dendrobium officinale pretreatments drying characteristics low field nuclear magnetic resonance |
|
| 点击此处可从《农业工程学报》浏览原始摘要信息 |
| 点击此处可从《农业工程学报》下载免费的PDF全文 |
|
