不同干燥方式对羊肚菌品质特性及复水性能的影响

    Effects of different drying methods on the quality characteristics and rehydration performance of Morchella esculenta

    • 摘要: 为探究羊肚菌在不同干燥方式及复水后的品质变化与成因,以六妹羊肚菌为试材,采用自然干燥(natural drying,ND),恒温干燥(constant temperature drying,CTD),真空冷冻干燥方式(vacuum freeze-drying,VFD)对羊肚菌进行干制,探讨3种干燥方式对微观结构、滋味、营养品质及复水性能的影响,并研究羊肚菌复水前后质地、色泽、风味的差异分析,分析判断不同方式的干燥特性。结果表明:VFD羊肚菌氨基酸、粗多糖与甜味值分别为944 mg/100 g、6.26 g/100 g、19.73,显著(P<0.05)高于其他2种方式,其菌柄与菌盖的明亮度(L*值)显著(P<0.05)提升,菌盖色差(△E)最小,△E值为5.83。电子鼻数据结合主成分分析 (principal component analysis,PCA)发现干燥与复水前后不同羊肚菌样品在气味轮廓上存在差异且对风味进行很好地区分。VFD由于其孔隙均匀分布的疏松状微观结构保持最佳的复水比,低场核磁共振结合核磁共振成像分析结果显示VFD羊肚菌在复水20 min内不易流动水显著增加,复水速率快速上升,复水均匀性最好。VFD复水后菌柄与菌盖色差(△E)分别为12.28和11.47,显著(P<0.05)小于其他2种干燥方式,菌柄和菌盖的脆度分别为35.87 N/mm和10.42 N/mm,与CTD相近。聚类分析与相关性分析结果直观地展示了感官变量与营养变量在不同干燥方式样品中的分布,进一步说明真空冷冻干燥在羊肚菌干燥应用的可行性。该研究结果为羊肚菌干制品加工方式优选提供参考。

       

      Abstract: Morchella esculenta was prone to decay and deterioration after harvesting and they were mainly circulated in the market as dried products. The choice of different drying methods was related to the quality characteristics of dried and rehydration products of Morchella esculenta, mainly including sensory and nutritional characteristics. The color, aroma, taste, type, and qualities of Morchella esculenta were mainly evaluated through five dimensions. In this study, Morchella sextelata (Mel-6) was used to explore the effect of different drying methods and rehydration treatments on its quality changes. Three strategies including natural drying (ND), constant temperature drying (CTD), and vacuum freeze-drying (VFD) were used to study their effects on the microstructure, taste, nutritional qualities, and rehydration performance of Morchella esculenta. The differences in texture, color, and flavor before and after rehydration, and their drying characteristics were analyzed. The results showed that the amino acids, crude polysaccharide, and sweetness of Morchella esculenta under VFD treatment were 944 mg/100 g、6.26 g/100 g、19.73 respectively, significantly higher (P<0.05) than the other two drying methods. The brightness of the stipe and cap of Morchella esculenta under VFD treatment was significantly improved (P<0.05) with less color difference, the value of △E was 5.83. Moreover, the volatile profiles analysis of Morchella esculenta before and after drying and rehydration treatment suggested a clear difference with distinguishable flavor components, according to the principal component analysis (PCA) of electronic nose data. The VFD-treated Morchella esculenta maintained the optimal rehydration ratio due to its porous microstructure with uniform pores distribution. The low-field nuclear magnetic resonance(LF-NMR) combined with magnetic resonance imaging (MRI) showed that the immobilized water of Morchella esculenta during the rehydration process was increased continuously with faster rehydration speed within 20 minutes and the best rehydration uniformity under VFD treatment. The color difference (△E) of the stipe and cap after VFD rehydration were 12.28 and 11.47 respectively, they changed less significantly (P<0.05) compared to the other two drying methods. The brittleness of the stipe and cap of Morchella esculenta after VFD rehydration were 35.87N/mm and 10.42N/mm, they remained similar with CTD. The distribution of sensory and nutritional variables in samples with different drying methods was intuitively demonstrated by the results of cluster and correlation analysis, The high-quality characteristics were maintained with vacuum freeze-drying technology during the drying and rehydration process of Morchella esculenta, further demonstrating the feasibility of vacuum freeze-drying in the drying of Morchella esculenta. These results would provide solid guidelines for the optimal processing method of dried Morchella esculenta products.

       

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