红外—对流滚筒干燥方式下烤烟叶丝质量的变化特征

目的]研究红外—对流干燥方式下烤烟叶丝质量的变化特征,为探索可行的烟草原料干燥新方法和新工艺提供基础理论依据和技术支持.方法]以2015年的重庆C041烤烟为原料,采用自行搭建的远红外滚筒干燥装置,考察红外—对流干燥过程对叶丝水含率、表面温度、弹性、填充值、内孔容积及叶丝结构等的影响,并与传统干燥方式下的结果进行对比分析,探究红外—对流干燥过程中叶丝孔径分布的变化.结果]红外—对流干燥过程中加大红外辐射温度、热风温度均对干燥过程起到强化作用;叶丝填充值随红外辐射温度的升高而增大,随热风温度的升高而减小;热风温度的升高会使叶丝弹性增大,叶丝弹性在红外温度为170℃时最大、145℃时最小;叶丝的内孔容积随红外温度的升高、热风温度的降低而增大,干燥过程中叶丝孔容比例变化较明显为孔径0.50~20.00和0.05~0.50μm;对比两种不同的干燥方式发现:红外—对流复合干燥下的叶丝填充值、内孔容积均大于传统干燥,而弹性相对较小、破碎度相对较高.结论]在一定范围内,提高红外辐射温度、降低热风温度均有利于维持叶丝的填充值,同时叶丝的孔容会呈规律性变化;与传统滚筒干燥相比,红外—对流滚筒干燥方式下的干燥速率相对较快,可在烟草实际干燥加工中推广应用.

Quality variations of cut tobacco cured by infrared-convection cylinder drying

Objective]Quality variations of cut tobacco cured by infrared-convection cylinder drying were investigated to provide basic theoretical basis and technical supports for exploring the new drying methods and techniques for tobacco raw materials.Method]Chongqing C041 cut tobacco in 2015 was used as material.It was dried by self built far infrared-cylinder dryer.The effects of infrared-convection drying process on moisture content,surface temperature,elasticity,fil-ling value,pore volume and structure of cut tobacco were investigated.The results were compared with those in the tradi-tional drying.In addition,variations of pore size distribution of cut tobacco in infrared-convective drying process were ex-plored.Result]Increasing the infrared radiation temperature and hot air temperature during infrared-convection drying could strengthen the effects.The filling value of tobacco rose with the increase of infrared radiation temperature,and de-creased with the increase of hot air temperature. The increase of the hot air increased the elasticity of tobacco.When the infrared temperature was 170℃,the elasticity was the largest,and when the temperature was 145℃the elasticity was the lowest.Pore volume of the tobacco enhanced with the increase of infrared temperature and the decrease of hot air tempera-ture.During the drying process,the proportion of pore volume changes was concentrated in the range of 0.50-20.00 and 0.05-0.50μm.Comparing on two different drying methods,it was found that filling value and pore volume of cut tobacco cured by infrared-convection drying were greater than those cured by traditional drying,and their elasticity was small, and degree of fragmentation was high.Conclusion]Within a certain range,improving infrared radiation temperature,re-ducing hot air temperature are beneficial to maintain filling value of cut tobacco,and pore volume also changes regularly. Compared with traditional drum drying,the drying rate of infrared-convection drying is faster,hence it should be applied in the actual drying process of cut tobacco.