莴苣红外杀青-热风、真空脉动干燥技术研究

Study of Lettuce Dry-blanching and Dehydration Using Sequential Infrared Radiation Heating,Hot Air Drying and Pulsed Vacuum Drying

杀青和干燥是提高脱水蔬菜加工品质的关键步骤,寻求蔬菜杀青和干燥的最优组合至关重要。以新鲜莴苣为原料,首先研究了催化式红外干法杀青和传统的热水漂烫杀青,然后对热风干燥和真空脉动干燥进行研究。通过对产品POD、VC以及颜色等质量指标进行测定,建立一种催化式红外杀青联合真空脉动干燥技术方法。试验证明,在红外辐射距离15 cm,杀青时间7 min,并采用60℃真空脉动干燥技术,脉动比设定15︰5,干燥时间99 min条件下,效果最佳。此时,POD相对活性降至20.17%,VC保留率为70%,色差值为ΔE为2.54,复水率为4.87。研究结果为后续的脱水莴苣工业化生产提供了依据。

Blanching and drying are the key steps to improve the processing quality of the dehydrated vegetables. It is very important to seek the best combination of blanching and drying. The infrared radiation and hot water were used to blanch fresh lettuces. Hot air drying and pulsed vacuum drying were used in drying process. The values of POD, VC and color indicators were established. The best processing method was infrared radiation distance of 15 cm, fixing time of 7 min for blanching, and 60 ℃ pulsed vacuum drying, pulsation ratio of 15 ： 5, drying time 99 min for drying. In this case, POD relative activity fell to 20.17%; VC preservation rate was 70%; The color difference AE value was 2.54 and the rehydration was 4.87. The results provide reference for the subsequent dehydration lettuce industrial production.