Abstract Drying is a complex unit operation widely applied in food processing. There is still an increasing interest to enhance the process, as well as the product quality and properties. In this work, ethanol was used to enhance drying of pumpkin, which has been considered as a structurally representative material of plant foods. The effect of ethanol treatment on microstructure, convective drying kinetics (Page model), rehydration kinetics (Peleg model) and viscoelastic properties (generalized Maxwell model) was evaluated. The pre-treatment was conducted by immersing pumpkin cylinders in ethanol before convective drying. The ethanol treatment accelerated both drying and rehydration processes. Microstructure modifications were observed after the ethanol treatment, drying and rehydration. The rehydrated samples (control and ethanol treated) showed different viscoelastic properties compared with those in natura, which presented low stress decay and more residual elasticity. A possible mechanism was proposed. In conclusion, the ethanol improved both drying and rehydration processes, without negatively impacting on the microstructure and viscoelastic properties of pumpkin cylinders.

中文翻译：

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乙醇预处理改善蔬菜干燥和再水化：动力学、机制和对粘弹性的影响

摘要 干燥是食品加工中广泛应用的复杂单元操作。人们对改进工艺以及产品质量和性能的兴趣越来越大。在这项工作中，乙醇被用来加强南瓜的干燥，南瓜被认为是植物性食物的结构代表材料。评估了乙醇处理对微观结构、对流干燥动力学（Page 模型）、再水化动力学（Peleg 模型）和粘弹性（广义麦克斯韦模型）的影响。预处理是通过在对流干燥之前将南瓜缸浸入乙醇中进行的。乙醇处理加速了干燥和再水化过程。在乙醇处理、干燥和再水化后观察到微结构改变。与天然样品相比，再水化样品（对照和乙醇处理）表现出不同的粘弹性，呈现出较低的应力衰减和更多的残余弹性。提出了一种可能的机制。总之，乙醇改善了干燥和再水化过程，而不会对南瓜圆柱体的微观结构和粘弹性产生负面影响。