辣椒的干燥特性和力学性能试验研究

Experimental Study on Drying Characteristics and Mechanical Properties of Pepper

为了降低辣椒在干燥及运输过程中的破损率,提高辣椒的干燥品质,对辣椒进行热风干燥的同时,进行拉伸和三点弯曲力学性能试验研究,并分析了辣椒的干燥特性和力学特性。试验结果表明:当干燥温度为45、60、75℃时,水分有效扩散系数分别为1.160096×10^(-10)、1.713660×10^(-10)、2.380429×10^(-10),随温度升高而升高。由阿伦尼乌斯公式计算得出辣椒活化能为22.0769kJ/mol,表明干燥过程中从辣椒中出去1mol的水分所需的最低能量是22.0769kJ。在75℃干燥温度下的辣椒拉伸力学性能试验中,随着加热时间的增加,平均最大载荷不断增大,加热300min后平均最大载荷曲线开始下降与前面干燥特性吻合,表明辣椒在前300min快速升温,降水速度快,表面自由水失去多,整体韧性增强导致所需载荷增大,干燥后期辣椒含水率较低,脆性增加,拉伸所需最大载荷降低;45℃干燥温度下,随着加热时间的增加,平均最大载荷变化不大。在不同含水率辣椒的三点弯曲试验中,含水率为14%时最大承受载荷约为3.5N,含水率为10%时最大承受载荷为约2.5N,含水率为6%时最大承受载荷约为1.1N,表明随着含水率的减小辣椒所能承受的最大载荷和压缩位移逐渐减小,辣椒抗压能力下降。研究结果可为提高辣椒干燥品质、降低运输过程中的破损提供理论依据。

In order to reduce the damage rate of pepper in the drying and transportation process and improve the drying quality of pepper,this paper conducted tensile and three-point bending mechanical properties test of hot air drying of pepper,and analyzed the drying characteristics and mechanical properties of pepper.The test results show that:When the drying temperature is 45℃,60℃and 75℃,the effective water diffusion coefficient is 1.160096×10^(-10),1.713660×10^(-10) and 2.380429×10^(-10),respectively.The effective water diffusion coefficient increases with the increase of temperature.According to Arrhenius formula,the activation energy of pepper is 22.0769kJ/mol,indicating that the minimum energy required to remove 1mol of water from pepper during drying is 22.0769kJ.In the tensile mechanical properties test of pepper,the average maximum load increased with the increase of heating time at 75℃ drying temperature,and the average maximum load curve began to decline after heating for 300min,which was consistent with the previous drying characteristics,indicating that the pepper heated up rapidly in the first 300min,the precipitation rate was fast,and the surface free water lost more.The overall toughness increased the required load,the water content of pepper was lower in the late drying period,the brittleness increased,and the maximum load required for tensile reduction.At 45℃,the average maximum load changes little with the increase of heating time.In the three-point bending test of pepper with different water content,when the water content is 14%,the maximum load-bearing load is about 3.5N,when the water content is 10%,the maximum load-bearing load is about 2.5N,and when the water content is 6%,the maximum load-bearing load is about 1.1N,indicating that with the decrease of water content,the maximum load and compression displacement that pepper can bear gradually decrease,and the compression resistance of pepper decreases.This study provides a theoretical basis for improving the drying quality of pepper and reducing the damage during transportation.