Science and Engineering Faculty, Queensland University of Technology (QUT), Brisbane, Queensland, Australia; Department of Mechanical Engineering, Dhaka University of Engineering & Technology, Gazipur, Gazipur-1700, Bangladesh.
Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2, Hungary; MTA - PTE Neurobiology of Stress Research Group, H-7624 Pécs, Ifjúság Street 20, Hungary.
Food Res Int. 2018 Mar;105:772-781. doi: 10.1016/j.foodres.2017.12.010. Epub 2017 Dec 5.
The cellular structure of food tissue is complex, and it is difficult to understand the morphological changes during drying. Three different cellular environments, namely intracellular space, intercellular space, and cell wall in food tissue contain a different proportion of water. It is crucial to understand the moisture migration mechanisms from different cellular environments during drying for improving energy efficiency and for ensuring better quality dried foods. Due to the lack of sufficient understanding of transport mechanisms of different types of water, existing mathematical models for food drying have been developed without considering these components separately. Therefore, the main aim of the present work is to investigate the transport mechanisms of cellular water during drying. Experiments were performed using H NMR T relaxometry to investigate the proportion of different types of water at various stages of drying, taking apple as a sample. It was found that intercellular water migrates from intracellular region to the intercellular spaces mainly through rupturing of the cell membranes during drying of apple tissue. The cell membrane ruptures take place at various stages of drying rather than collapsing at one time. Interestingly, the trends of rupturing the cell membranes follow mostly a uniform pattern as rupturing takes places almost at a regular interval. The results were compared with the rupturing mechanism in the low porous material (potato) reported in authors' previous study. It was also observed that most of the cell membranes of potato tissue rupture at middle stages of drying while apple tissues rapture mostly uniformly. The penetration rate of heat energy with the pressure gradient between intracellular and intercellular environments are the predominant factors that cause the rupturing the cell membranes.
食物组织的细胞结构复杂，难以理解干燥过程中的形态变化。食物组织中的三个不同的细胞环境，即细胞内空间、细胞间隙和细胞壁，含有不同比例的水。了解干燥过程中不同细胞环境中水分迁移的机制对于提高能源效率和确保更好质量的干燥食品至关重要。由于对不同类型水分的传输机制缺乏足够的了解，现有的食品干燥数学模型没有分别考虑这些成分。因此，本工作的主要目的是研究干燥过程中细胞水的传输机制。实验采用 H NMR T 弛豫谱法研究了苹果在不同干燥阶段不同类型水分的比例。结果表明，在苹果组织干燥过程中，细胞间水主要通过细胞膜破裂从细胞内区迁移到细胞间隙。细胞膜破裂发生在干燥的各个阶段，而不是一次性崩溃。有趣的是，细胞膜破裂的趋势基本遵循一致的模式，因为破裂几乎在固定的间隔发生。结果与作者之前研究中报道的低多孔材料（土豆）中的破裂机制进行了比较。还观察到，大多数土豆组织的细胞膜在干燥的中期破裂，而苹果组织则均匀破裂。细胞内和细胞间隙环境之间的压力梯度引起的热能和渗透速率是导致细胞膜破裂的主要因素。
