竹笋热风薄层干燥特性及动力学分析

Analysis of Hot-air Thin Layer Drying Characteristics and Kinetics Model of Bamboo Shoots

干燥是竹笋加工中最为常见的一种方式,为了解竹笋在热风薄层干燥条件下的干燥特性,本实验以大叶麻竹笋为试验原料,竹笋片干基含水率和干燥速率为试验测试指标,研究了不同干燥温度、风速和笋片厚度等因素对干燥速率的影响,并建立竹笋热风薄层干燥的动力学模型。结果表明:热风薄层干燥温度、风速和笋片厚度均对竹笋的干燥特性影响较大。随着干燥温度和风速的升高,干燥速率增加;随着笋片厚度的增加,干燥速率降低。不同条件下的干燥均可分为加速、恒速和降速干燥3个阶段。竹笋的适宜热风薄层干燥条件为干燥温度80℃、风速2.0 m/s、笋片厚度1.0 cm。竹笋热风薄层干燥的动力学满足Page模型,Page模型适合对竹笋热风薄层干燥过程进行描述和预测。所得研究结果将为竹笋干的热风薄层干燥可控制工业化生产提供参考。

Drying is one of the most common ways in bamboo shoots processing and is the key to affect the quality of dried bamboo shoots. In order to evaluate the drying characteristics of bamboo shoots and determine the most appropriate drying model under the hot-air thin layer drying conditions, the moisture content and drying rate of bamboo shoots studies were carried out during hot-air thin layer drying process. The effects of drying temperature, air speed and slice thickness on the drying characteristics were determined and hot-air thin layer drying kinetics model of bamboo shoots was set up. The results showed that the hot-air thin layer temperature, air speed and slice thickness had greater influences on the drying characteristics of bamboo shoots. The drying rate increased with the increase of drying temperature and air speed, whereas the drying rate gradually decreased with the increase of slice thickness. The whole drying process was divided into three stages with different conditions, including the accelerated drying, constant rate drying and falling rate drying. The most appropriate hot-air thin layer drying conditions were drying temperature 80 ~C, air speed 2.0 m/s, and slice thickness 1.0 cm. The hot-air thin layer drying kinetics met Page model and this model was suitable for describing and predicting the hot-air thin layer drying of bamboo shoots. The research may provide a reference for industrial production of dried bamboo shoots or other dried vegetables.