怀山药恒温及变温红外喷动床干燥动力学、均匀性及品质特性研究

Studies on Drying Kinetics, Uniformity and Quality Characteristics of Chinese YamDried by Infrared-Assisted Spouted Bed at Constant and Variable Temperature

采用恒温干燥(40,50,60,70℃)和阶段变温干燥(阶段升温和阶段降温)工艺对怀山药进行红外喷动床干燥(IRSBD)处理,研究其对干燥动力学、均匀性及品质特性(质构、复水性能、总酚含量、微观结构和皱缩率)的影响。对怀山药红外喷动床干燥曲线的数学模型拟合结果表明,Midilli模型R2最大(0.99989),RMSE和χ2最小(分别为0.00319和1.69872×10-5),最适合描述怀山药IRSBD动力学。对比不同干燥工艺发现,恒温干燥条件下,提高干燥温度有利于缩短干燥时间,降低能耗。阶段升温干燥能耗仅高于70℃恒温干燥,其干燥均匀性最好,样品总酚含量最高为(85.25±7.41)mg GAE/100 g DW,皱缩率及硬度最低,分别为(74.3±3.96)%和(24.95±7.41)N,且有良好的色泽。阶段降温干燥样品具有较高的平衡复水比和脆度,然而在干燥时间、能耗、均匀性及产品硬度、皱缩率和总酚含量方面没有显著优势。结论:阶段升温干燥是怀山药IRSBD更为理想的干燥工艺。研究结果可为IRSBD技术应用于农产品加工提供理论参考。

In this study,infrared-assisted spouted bed drying(IRSBD)of Chinese yam was carried out using constant temperature drying(40,50,60℃and 70℃)and variable temperature drying(staged rising temperature and staged falling temperature)processes to investigate the effects on drying kinetics,uniformity,and quality properties(texture,rehydration,total phenolic content,microstructure,and shrinkage).The mathematical modeling results of the Chinese yam IRSBD drying curve showed that the Midilli model had the best fit,with the maximum R2 value(0.99989)and the minimum RMSE andχ2 values(0.00319 and 1.69872×10-5,respectively),indicating that it was most suitable for describing the IRSBD kinetics of Chinese yam.In the comparative analysis of different drying processes,it was found that increasing the drying temperature under constant-temperature drying conditions was beneficial for shortening the drying time and reducing energy consumption.Staged rising temperature drying had energy consumption only slightly higher than that of constant-temperature drying at 70℃,but it exhibited the best drying uniformity,the highest total phenolic content[(85.25±7.41)mg GAE/100 g DW],and the lowest shrinkage and hardness[(74.3±3.96)%and(24.95±7.41)N],respectively,as well as a desirable color.The staged falling drying process produced samples with higher equilibrium rehydration ratio and crispness,but it did not show significant advantages over the staged rising temperature process in terms of drying time,energy consumption,uniformity,hardness,shrinkage ratio,and total phenolic content.Therefore,it can be concluded that staged rising temperature drying is a more ideal drying process for Chinese yam using IRSBD.This study provides data reference and theoretical support for the application of IRSBD technology in agricultural product processing and industrial production.