不同功率的超声波预处理对罗非鱼片冻干性能的影响

Vacuum Freeze-Drying of Ultrasonic Dehydrated Tilapia Fillets

为了探讨超声波预处理在维持肉类食品冻干品质和加快冻干过程的综合效果,以罗非鱼为实验材料,进行了不同功率（200 W,250 W,300 W,350 W,400 W,450 W,500 W）的超声波预处理罗非鱼片的真空冷冻干燥实验,获得了不同功率预处理条件下的冻干曲线,水分分布曲线和系列品质指标变化规律曲线。结果表明,经超声波预处理的样品冻干前期升温速度慢,后期升温速度快,且以450 W功率预处理的样品升温和达到平缓状态最快。在相同的冻干参数和冻干时间条件下,不同功率超声波预处理的冻干样品、干基含水率、水分活度、白度值、复水率、质构和水分状态及其分布等都存在着一定的差异,且均优于无预处理的对照样品。以各指标的加权综合评分值为比较标准,不同超声波功率预处理的样品与对照组相比提升幅度在68.55%～273.42%不等,且以450 W超声波预处理的样品品质提升幅度最大,综合性能较优。结论能为超声预处理在冻干肉类产品中的应用提供参考。

We experimentally addressed the vacuum freeze-drying of the ultrasonic dehydratedtilapia fillets. The impact of the ultrasonic power on the vacuum freeze-drying behavior, including the moisture＇ s content, state and distribution, water activity, whiteness, rehydration-rate and texture, was investigated. The results show that the ultrasonic dehydration significantly improved the quality of freeze-dried tilapia fillets. For example, depending on the ultrasonic power, the temperature of the dehydrated sampleincreased slowly in the early stage but much faster in the later stage in freeze-drying, reaching most rapidly to a plateau at 450 W. As the power increased, the moisture con- tent and water activity changed in a decrease-increase mode;in contrast, the rehydration-rateand whiteness varied in an increase-decrease manner. Evaluated of the properties in weighted-score method, the ultrasonic dehydration in- creased the score by 68.55% to 273.42% （at 450 W）. Moreover, the ultrasonic dehydration remarkably bettered the chewiness and taste of the vacuum freeze-dried tilapia fillets.