Comparative Evaluation of Cold Plasma‐Assisted Infrared and Hot Air Drying of Yam: Drying Kinetics, Energy Consumption, and Quality Attributes
Chen Shen, Wenqing Chen, Ce Yang, Tariq Aziz, Nawal H. Siddig, Nawal Al‐Hoshani, Fahad Al‐Asmari, Haiying Cui, Lin LinABSTRACT
Conventional hot air drying (HAD) of yam is associated with prolonged processing time, high energy consumption, and quality deterioration caused by extended thermal exposure and nonuniform moisture removal. Infrared drying (IRD) can accelerate energy transfer, but rapid energy input does not necessarily eliminate limitations associated with internal moisture migration in high‐moisture plant tissues. In this study, cold plasma (CP) pretreatment was combined with IRD to improve the drying performance of yam, and its effects were systematically compared with HAD, IRD, and CP‐assisted HAD (HAD + CP). Drying temperature evolution, drying kinetics, energy consumption, drying uniformity, structural and microstructural characteristics, and selected quality attributes were evaluated. Compared with HAD, IRD increased the drying rate by 37.5% and reduced energy consumption from 8847.23 to 6524.625 kJ/mol. CP pretreatment further accelerated moisture removal and improved drying uniformity, with the final moisture‐content relative standard deviation decreasing from 25.23% for HAD to 13.10% for IRD + CP. Microstructural observations indicated that CP‐assisted drying reduced excessive tissue collapse and maintained a relatively more intact cellular morphology. Consequently, IRD + CP achieved the highest rehydration ratio of 2.76, and improved retention of total flavonoids compared with conventional HAD. FTIR analysis showed that the major functional groups of yam were generally preserved, although CP induced changes in hydroxyl‐ and water‐associated molecular environments. Overall, the results suggest that CP pretreatment can complement the rapid energy input of IRD by modifying the tissue response to dehydration and facilitating moisture migration. The combined process therefore shows potential for energy‐efficient and quality‐oriented yam drying. Further pilot‐scale studies are required to optimize CP treatment, infrared energy input, loading conditions, and overall process energy efficiency before industrial implementation.