广陈皮含水率动态特性试验研究

Experimental Study on Dynamic Characteristics of Moisture Content of Citrus Reticulata‘Chachi’

针对目前广陈皮仓储过程中含水率实时检测方法不完善和缺少含水率动态模型以及精准控制手段等问题,以空气相对湿度为变量研究不同年份广陈皮含水率双向(干燥/增湿)动态特性。在试验条件下,实时检测样本动态质量,测量确定样本含水率,通过标定获取样本动态含水率,并对含水率变化过程进行建模,分析其动态特性。结果表明:干燥过程中,4.0 h附近出现临界点,临界点之前,老皮含水率变化快;临界点之后,新皮含水率变化快,其动态特性体现出新皮惯性较大的特性。增湿过程中,6.5 h附近出现临界点,临界点之前,新皮含水率变化快;临界点之后,老皮含水率变化快,体现出与干燥试验相反的特性。研究结果为广陈皮仓储条件精准自动控制提供试验依据,为广陈皮按年份分类仓储控制方案提供参考。

Citrus reticulata‘Chachi’needs an aging storage process,and the rapid development of its industrial scale requires large-scale storage and standardization.Moisture content is the most important control target in the process of Citrus reticulata‘Chachi’,which not only affects the aging effect of the peel,but also causes mildew.At present,the relative humidity of air is used as the parameter of closed-loop control in the main automatic warehouses of Citrus reticulata‘Chachi’enterprises,but there is no real-time monitoring method to directly obtain the moisture content of Citrus reticulata‘Chachi’,and the dynamic mathematical model of the moisture content has been a technical blind spot.In view of the above problems,based on the unidirectional influence of temperature and air velocity on the exchange velocity between the water molecules in the orange peel and the outside air,this paper takes air humidity as the input variable to study the bidirectional(drying/humidifying) dynamic characteristics of the moisture content of Citrus reticulata‘Chachi’in different years.Under the experimental conditions,consider the change in the sample mass as a result of the gain or the loss of sample water molecules.The dynamic quality of samples was detected in real time,and a certain number of samples moisture content were measured.The dynamic moisture content of samples was obtained by demarcated,and the change process of the moisture content was modeled to analyze its dynamic characteristics.The results showed that the moisture content of new peel was the highest in the same environment,and the moisture content decreased with the increase of aging year.The moisture content curves of samples change with exponential function.The dynamic water content derivative curve of Citrus reticulata‘Chachi’in different years has a critical point,and the water content derivative curve near the critical point has a regular transcendence.That is to say,a critical point appeared around 4 hours during the drying process.Before the critical point,the moisture content of the old peel changed rapidly;after the critical point,the moisture content of the new peel changed rapidly,and its dynamic characteristics showed that the new peel had a large inertia.During the humidification process,a critical point appeared around 6.5 hours,before the critical point,the moisture content of the peel with less age changed rapidly,after the critical point,the moisture content of the older peel changed rapidly,reflecting the opposite characteristics of the drying test.The following conclusions can be drawn:In the process of the storage control,the moisture content of the new peel is large,and attention should be paid to drying in time to prevent mildew;with the increase of aging time,the dehydration rate is gradually strengthened during drying,and the absorption rate of water in high humidity environment is gradually weekend.From the perspective of storage,the aging year is longer and the peel is easier to preserve.The results provide the experimental basis for the accurate automatic control of the storage conditions of Citrus reticulata‘Chachi’,and provide a reference for the storage control scheme of Citrus reticulata‘Chachi’classified by year.