TIAN Feifan, XU Mingqiang, ZHANG Jian, MIAO Ruiyin, WANG Ruizhu, CHEN Kai
To investigate the effects of plasma treatment time and heat pump drying temperature on the drying characteristics and quality of jujube slices, this study employed atmospheric pressure plasma jet (APPJ) to pretreat jujube slices (0, 2, 5, and 8 s), followed by heat pump drying at different temperatures (40, 50, and 60 ℃).The effects of different plasma treatment times and drying temperatures on the drying characteristics, small-molecule sugar content, total phenols, total flavonoids, texture properties, and color of jujube slices were analyzed.A fuzzy mathematical sensory evaluation model was established to validate their acceptability.The results showed that heat pump drying after plasma treatment required less time.The APPJ5s-60 ℃ group exhibited the greatest reduction in drying time compared to APPJ0s-60 ℃ (20% decrease).Scanning electron microscope observations revealed that plasma treatment etched the surface of jujube slices, creating larger pores and forming new moisture transport channels, which facilitated water loss and directly improved the drying rate.By fitting four commonly used empirical drying models (Page, Logarithmic, Verma model, and Wang and Singh), it was found that the Page model accurately described the moisture change of jujube slices dried at 40 ℃ and 60 ℃, while the Logarithmic model provided a better fit for those dried at 50 ℃.Plasma treatment also influenced the content of small-molecule sugars, total phenols, and total flavonoids in jujube slices.Compared with APPJ0s-50 ℃, the APPJ5s-50 ℃ group showed a 1.73% increase in total small-molecule sugar content, an 11.92% increase in total phenols, and a 4.24% increase in total flavonoids.Additionally, plasma treatment created a complex pore structure in the jujube slices, enhancing their crispness and chewiness, thereby improving their texture properties.Based on the constructed fuzzy sensory mathematical model, the comprehensive evaluation scores of plasma-treated jujube slices increased, with the APPJ5s-50 ℃ group scoring the highest at 91.96.In conclusion, plasma treatment can alter the surface structure of jujube slices, accelerating the drying process and directly reducing thermal reaction time during drying, thereby improving drying efficiency and the retention of nutritional quality.The APPJ5s-50 ℃ group preserved the original quality of jujube slices and achieved the highest fuzzy mathematical sensory evaluation score, making it more acceptable to consumers.
