Authors

Abstract

Temperature uniformity (σ) during forced-air precooling of fruits and vegetables plays a critical role in preserving quality and extending shelf life. However, inconsistencies in evaluation criteria for calculating σ remain a significant challenge. In this study, cherries were selected as the model system, and computational fluid dynamics (CFD) simulations were employed to analyze three commonly used temperature uniformity indices, namely σ1, σ2 and σ3. The results show that σ₁ is highly sensitive to variations in average temperature during forced-air precooling and becomes unsuitable when the average temperature approaches 0 °C. Moreover, σ₁ yields relatively large values, often exceeding 1. Both σ₂ and σ₃ primarily reflect variations in the temperature range during precooling. However, since σ₂ incorporates temperature in Kelvin in its denominator, its values are generally below 0.1. In contrast, σ₃ remains stable within the range of 0 to 1 throughout the precooling process. Overall, the results indicate that σ₃ is the most suitable index for evaluating temperature uniformity in fruits and vegetables during forced-air precooling.

Abstract in Chinese

果蔬压差预冷过程中的温度均匀性（σ）对于保持其品质和延长其货架期起着至关重要的作用。然而，目前计算σ的评价标准不一致。本研究以蓝莓为研究对象，利用计算流体动力学（CFD）模拟分析了三种常用的温度均匀性评价方法，即σ1、σ2和σ3。研究结果表明，σ1对强制空气预冷过程中平均温度的波动表现出更高的敏感性，并证明在平均温度低于0℃的条件下无法使用。此外，σ1得出的值相对较大，其最大值通常超过1。σ2和σ3主要反映了压差预冷过程中温度范围的变化。然而，由于σ2的分母中包含了开尔文温度，因此所得值通常低于0.1。相比之下，σ3在整个预冷过程中保持0~1范围内的稳定值。综合分析表明，σ3是评估预冷过程中果蔬温度分布均匀性的最合适指标。