The structural heterogeneities of fruits and vegetables intensify the complexity to comprehend the interrelated physicochemical changes that occur during drying. Shrinkage of food materials during drying is a common physical phenomenon which affects the textural quality and taste of the dried product. The shrinkage of food material depends on many factors including material characteristics, microstructure, mechanical properties, and process conditions. Understanding the effect of these influencing factors on deformation of fruits and vegetables during drying is crucial to obtain better‐quality product. The majority of the previous studies regarding shrinkage are either experimental or empirical; however, such studies cannot provide a realistic understanding of the physical phenomena behind the material shrinkage. In contrast, theoretical modeling can provide better insights into the shrinkage that accompanies simultaneous heat and mass transfer during drying. However, limited studies have been conducted on the theoretical modeling of shrinkage of fruits and vegetables. Therefore, the main aim of this paper is to critically review the existing theoretical shrinkage models and present a framework for a theoretical model for the shrinkage mechanism. This paper also describes the effect of different drying conditions on material shrinkage. Discussions on how the diverse characteristics of fruits and vegetables affect shrinkage propagation is presented. Moreover, a comprehensive review of formulation techniques of shrinking models and their results are also presented. Finally, the challenges in developing a physics‐based shrinkage model are discussed.

中文翻译：

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干燥过程中食品材料的收缩：现状和挑战

水果和蔬菜的结构异质性加剧了理解在干燥过程中发生的相关物理化学变化的复杂性。干燥过程中食品材料的收缩是一种常见的物理现象，会影响干燥产品的质地质量和味道。食品原料的收缩取决于许多因素，包括原料特性，微观结构，机械性能和加工条件。了解这些影响因素对水果和蔬菜在干燥过程中变形的影响对于获得更高质量的产品至关重要。先前有关收缩的大多数研究都是实验性的或经验性的。但是，这样的研究不能对材料收缩背后的物理现象提供现实的理解。相比之下，理论模型可以更好地了解干燥过程中同时发生的传热和传质收缩率。然而，关于水果和蔬菜收缩的理论模型已经进行了有限的研究。因此，本文的主要目的是严格审查现有的理论收缩模型，并为收缩机理的理论模型提供框架。本文还描述了不同干燥条件对材料收缩的影响。讨论了水果和蔬菜的不同特性如何影响收缩传播。此外，还对收缩模型的制定技术及其结果进行了全面回顾。最后，讨论了开发基于物理的收缩模型的挑战。