热风干燥对黑木耳品质的影响

Effect of Hot Air-Drying on Quality of Auricularia auricula

为探索黑木耳的热风干燥工艺技术,比较不同热风温度对黑木耳干燥特性的影响,以自然晾晒干燥和冷冻干燥为对照,对热风干燥黑木耳的水分分布、复水性能和抗氧化活性进行分析。结果表明:黑木耳在85℃下的热风干燥速率高于55℃和70℃,干燥过程由升速阶段和降速阶段组成。对干燥动力学模型进行拟合,发现Page模型为最佳干燥动力学模型。低场核磁共振横向弛豫时间曲线显示,热风干燥前黑木耳中的水分以自由水为主;85℃热风干燥黑木耳的复水性能略高于55℃和70℃,显著高于自然晾晒样品(P<0.05)。热风干燥黑木耳的1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力和β-胡萝卜素保护能力均显著高于自然晾晒样品(P<0.05),85℃热风干燥黑木耳的DPPH自由基清除能力和β-胡萝卜素保护能力分别为150.6、138.9μg Trolox/g md。综上所述,85℃热风干燥工艺操作简单,可以较好地保持黑木耳干制品的品质,该研究为黑木耳干燥干燥过程中的品质调控提供了理论依据。

In order to explore the feasibility of suitable hot-air drying technology of Auricularia auricula,the effects of hot air-drying temperature on drying characteristics were investigated.Moisture distribution,rehydration property and antioxidant activity of hot-air dried Auricularia auricula were analyzed compared with those of natural drying and freeze-drying.The results showed that high temperature(85℃)of hot air enhanced the drying rate compared to low temperature(55℃and 70℃).Two distinct drying stages were observed for hot air-drying:an initial heating stage characterized by a rapid increase in the drying rate,followed by a falling drying rate stage.Page model could better describe Auricularia auricula drying behavior among five tested mathematical models.Low-field nuclear magnetic resonance transverse relaxation time(T2)inversion spectrum showed that the water in undried Auricularia auricula was mainly bound water.The rehydration capacity of Auricularia auricula dried at 85℃which was significantly higher than that of natural drying(P<0.05),slightly higer than those of samples at 55℃and 70℃.Hot air-dried Auricularia auricula exhibited higher(1,1-diphenyl-2-picrylhydrazyl)(DPPH)radical scavenging andβ-carotene protection activities compared with that of natural drying(P<0.05).DPPH radical scavenging andβ-carotene protection activity for Auricularia auricula dried at 85℃were 150.6 and 138.9μg Trolox/g dry weight,respectively.Therefore,hot air-drying at 85℃could be suggested for the production of dehydrated Auricularia auricula with better physical qualities.This study provided a theoretical basis for the quality control during the drying process of Auricularia auricula.