不同干燥方法对香菇片品质及微观结构的影响

Effects of different drying methods on the quality and microstructure of shiitake slices

为研究一种合适的干香菇片加工工艺,比较了真空冷冻干燥(freeze-drying,FD)、变功率间歇微波干燥(intermittent microwave drying at different power,IMD)、热风-微波分段联合干燥(hot air followed by microwave drying,HAD+MD)、真空冷冻-微波联合干燥(freeze drying followed by microwave drying,FD+MD)、微波-真空冷冻联合干燥(microwave drying followed by freeze drying,MD+FD)处理对香菇片理化指标、色泽、质构、外观及微观结构的影响,并利用加权灰色关联度分析法计算综合评分。结果显示,FD的ΔE值(10. 76±0. 83)、复重系数[(59. 09±3. 91)%]最高(P <0. 05),粗蛋白、香菇多糖和还原糖的综合保留率高。FD+MD的皱缩率和粉碎度与FD相近(P> 0. 05)。质地测试表明,FD+MD和MD+FD的硬度和弹性与FD相近(P> 0. 05),但咀嚼性和回复性优于FD。IMD和HAD+MD表面形成硬壳,皱缩褐变严重。IMD的甲醛含量[(28. 02±0. 62) mg/kg]最低(P <0. 05)。微观结构显示FD、FD+MD、MD+FD三组呈均匀的蜂窝状结构。综合评价结果为:FD+MD>FD> MD+FD> HAD+MD> IMD。综上,5种方法中,FD+MD最适合加工干香菇片。该研究为香菇干制品加工及品质评价提供了思路。

In order to investigate a suitable processing technology to produce dried shiitake slices,this research evaluated the effects of five drying methods,including freeze-drying( FD),intermittent microwave drying at different power( IMD),hot air followed by microwave drying( HAD + MD),freeze-drying followed by microwave drying( FD + MD),and microwave drying followed by freeze-drying( MD + FD),on shiitake slices quality in terms of their physicochemical properties,color,texture,appearance and microstructure. A comprehensive evaluation was performed using grey correlation analysis based on the coefficient of variation. Results showed that the value of ΔE( 10. 76 ± 0. 83) and rehydration coefficient [( 59. 09 ± 3. 91) %] in FD were significantly better than other groups( P <0. 05). Furthermore,the comprehensive retention of crude protein,lentinan and reducing sugar in FD were great. The shrinkage and fragmentation of FD + MD were similar to FD( P > 0. 05). Texture test showed that the hardness and springness of FD + MD and MD + FD were similar to FD( P > 0. 05),and the chewiness and resilience of them were better than FD. And the surface of IMD and HAD + MD formed hard shell which resulting in severe shrinkage and browning. However,the formaldehyde content of IMD [( 28. 02 ± 0. 62) mg/kg]was the lowest( P < 0. 05). Moreover,a uniform and full honeycomb network microstructure were observed in FD,FD + MD and MD + FD. The comprehensive evaluation result was: FD + MD > FD > MD + FD > HAD + MD > IMD. Therefore,FD + MD was a promising method for processing dried shiitake slices in these five methods. This study provides ideas for processing and quality evaluation of dried shiitake products.