不同预干燥方式对瞬时压差膨化香菇脆品质特性的影响

Effect of Different Pre-drying Methods on the Quality Attributes of Instant Controlled Pressure Drop Puffing Dried Shiitake(Lentinus edodes)Crisps

为探究预干燥方式对瞬时压差膨化(instant controlled pressure drop,DIC)整果香菇脆品质特性影响,开发即食香菇脆休闲食品,本文研究了热风干燥(hot air drying,HAD)、热泵干燥(heat pump drying,HPD)和真空冷冻干燥(vacuum freeze drying,FD)等3种预干燥方式对DIC香菇脆品质的影响。结果表明,香菇脆总干燥时间取决于预干燥方式,由低至高为:HAD-DIC<HPD-DIC<FD-DIC;平均干燥速率则与之相反。总色差由低到高为:FD-DIC<HPD-DIC<HAD-DIC。膨化度高低顺序为:HPD-DIC>HAD-DIC>FD-DIC。复水比高低顺序为:FDDIC>HPD-DIC>HAD-DIC。HAD-DIC香菇脆硬度值最高,脆度值最低;FD-DIC香菇脆硬度和脆度均较低;HPDDIC香菇脆硬度适中且脆度最高。总糖含量高低顺序为:FD-DIC>HPD-DIC>HAD-DIC。低场核磁共振(low field nuclear magnetic resonance,LF-NMR)结果表明,相比于FD和HAD预干燥,HPD后的香菇疏松结合水和不易流动水所占比例较高,紧密结合水比例较低,有利于DIC瞬间泄压时水分闪蒸,为香菇膨化提供充足驱动力。综合考虑,香菇脆最适预干燥方式为HPD。

In order to explore the effect of pre-drying methods on the quality attributes of instant controlled pressure drop puffing(DIC)dried whole shiitake(Lentinus edodes)crisps and develop ready-to-eat L.edodes snack food,this study investigated the influence of three different pre-drying methods,viz.,hot air drying(HAD),heat pump drying(HPD)and vacuum freeze drying(FD)on the quality attributes of L.edodes crisp.The results showed that the total drying time of L.edodes crisps depended on the pre-drying method,following the order of HAD-DIC<HPD-DIC<FD-DIC.Opposite tendency was observed in the average drying rate.The total color difference of L.edodes followed the order of FD-DIC<HPD-DIC<HAD-DIC.The puffing degree of L.edodes crisps followed the order of HPD-DIC>HAD-DIC>FD-DIC.The rehydration ratio of L.edodes crisps followed the order of FD-DIC>HPD-DIC>HAD-DIC.HAD-DIC resulted in the highest hardness and lowest brittleness.FD-DIC resulted in the lower hardness and crispness.HPD-DIC resulted in the highest crispness and optimal hardness.The total sugar content of L.edodes crisps followed the order of FD-DIC>HPD-DIC>HAD-DIC.Low field nuclear magnetic resonance(LF-NMR)revealed that compared with HAD and FD,the proportion of tightly bound water and immobilized water in L.edodes after HPD was higher,and the proportion of tightly bound water was lower,which was conductive to water flash evaporation during DIC processing thus providing sufficient driving force for the puffing of Lentinus edodes.In conclusion,HPD was the best pre-drying method for L.edodes crisps.