Abstract In this study X-ray computed tomography (X-ray CT) was used to determine microstructural properties of ‘Fuji’ apple (Malus domestica Borkh.) tissue affected by internal browning (IB) and unaffected tissue after short-term exposure (3 days) to a storage atmosphere with 0.1 % O2 and 50 % CO2. The incidence of IB disorders were concentrated in the core of the fruit. IB developed in 31 % of fruit at varying degrees of severity, due to differences in microstructural and morphological properties of individual fruit. X-ray CT scanning was able to give pore and cell microstructural information such as porosity, length, sphericity, connectivity, equivalent diameter, and anisotropy. High-resolution scans showed that fruit tissue with IB had a lower total porosity and pore connectivity compared to unaffected fruit tissue, possibly due to membrane damage and flooding of intercellular spaces with cellular fluids. The pores in affected brown tissue were significantly more spherical as compared to the other tissue types. Low-resolution (full fruit) scans showed that the density of fruit tissue affected by IB was not significantly different from that of unaffected fruit tissue. Low porosity in the fruit core region restricts gas transport and predisposes the core region to CO2 induced IB. This work provided a novel and in-depth insight into the effects of short-term high CO2/low O2 stress conditions on the microstructural properties of South African grown ‘Fuji’ apples. Furthermore, this study showed that tissue microstructure influences the susceptibility of different regions within the same fruit to stress-induced IB symptoms.

中文翻译：

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使用 X 射线计算机断层扫描和 3D 图像分析来表征暴露于 CO2 胁迫后“富士”苹果的内部褐变

摘要 在这项研究中，X 射线计算机断层扫描 (X 射线 CT) 用于确定受内部褐变 (IB) 影响的“富士”苹果 (Malusdomestica Borkh.) 组织和短期暴露后未受影响的组织的微观结构特性 (3天）到含有 0.1% O2 和 50% CO2 的储存环境。IB病的发生集中在果实的核心部位。由于单个水果的微观结构和形态特性不同，IB 在 31% 的水果中发生了不同程度的严重程度。X 射线 CT 扫描能够提供孔隙和细胞微观结构信息，例如孔隙率、长度、球形度、连通性、等效直径和各向异性。高分辨率扫描显示，与未受影响的水果组织相比，具有 IB 的水果组织的总孔隙率和孔隙连通性较低，可能是由于细胞膜损伤和细胞间隙充斥细胞液所致。与其他组织类型相比，受影响的棕色组织中的孔明显更呈球形。低分辨率（全果）扫描显示受 IB 影响的水果组织的密度与未受影响的水果组织的密度没有显着差异。果核区域的低孔隙率限制了气体运输，并使核心区域易于受到 CO2 诱导的 IB 的影响。这项工作为短期高 CO2/低 O2 压力条件对南非种植的“富士”苹果的微观结构特性的影响提供了新颖而深入的见解。此外，这项研究表明，组织微观结构会影响同一水果内不同区域对应激诱导的 IB 症状的易感性。