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Three-dimensional pore space quantification of apple tissue using X-ray computed microtomography

BIOSYST, MeBioS, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, W. de Croylaan 42, 3001 Leuven, Belgium.
Planta (Impact Factor: 3.38). 08/2007; 226(3):559-70. DOI: 10.1007/s00425-007-0504-4
Source: PubMed

ABSTRACT The microstructure and the connectivity of the pore space are important variables for better understanding of the complex gas transport phenomena that occur in plant tissues. In this study, we present an experimental procedure for image acquisition and image processing to quantitatively characterize in 3D the pore space of apple tissues (Malus domestica Borkh.) for two cultivars (Jonagold and Braeburn) taken from the fleshy part of the cortex using X-ray computer microtomography. Preliminary sensitivity analyses were performed to determine the effect of the resolution and the volume size (REV, representative elementary volume analysis) on the computed porosity of apple samples. For comparison among cultivars, geometrical properties such as porosity, specific surface area, number of disconnected pore volumes and their distribution parameters were extracted and analyzed in triplicate based on the 3D skeletonization of the pore space (medial axis analysis). The results showed that microtomography provides a resolution at the micrometer level to quantitatively analyze and characterize the 3D topology of the pore space in apple tissue. The computed porosity was confirmed to be highly dependent of the resolution used, and the minimum REV of the cortical flesh of apple fruit was estimated to be 1.3 mm(3). Comparisons among the two cultivars using a resolution of 8.5 mum with a minimum REV cube showed that in spite of the complexity and variability of the pore space network observed in Jonagold and Braeburn apples, the extracted parameters from the medial axis were significantly different (P-value < 0.05). Medial axis parameters showed potential to differentiate the microstructure between the two evaluated apple cultivars.

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    • "Biol. (2014), http://dx.doi.org/10.1016/j.jsb.2014.08.003 cated software now available for the tomographic reconstructions and interpretations (Mendoza et al., 2007; Verboven et al., 2012, 2013). "
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    Journal of Structural Biology 10/2014; 188(1). DOI:10.1016/j.jsb.2014.08.003 · 3.23 Impact Factor
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    • "This has been demonstrated for the ripening of climacteric fruits like; tomato (Kelly and Saltveit 1988; Saltveit and Sharaf 1992; McDonald et al. 1996) and apple (Pesis et al. 1994; Pesis 1995). Besides this, levels of volatiles are also found to be associated with storage disorders of apple fruit like; scald (Huelin and Coggiola 1968) and internal browning (Mendoza et al. 2007). The ripening and quality of non-climacteric fruits such as; grapes, orange and strawberries were also influenced by these volatiles (Saltveit and Ballinger 1983; Ke and Kader 1990; Ke et al. 1991). "
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    • "For image processing the following steps were applied (Herremans et al., 2013) using CTAn 1.12.0.0 software (Bruker microCT, Kontich, Belgium): the datasets were cropped on all sample edges (0.8 mm) to remove approximately 4–5 outer cell layers that are potentially damaged by sample preparation. The final tissue volume for analysis measured 55 mm 3 , well above the 1.3 mm 3 limit that has been shown to representatively describe apple tissue microstructure in terms of its porosity (Mendoza et al., 2007). The grey scale images were median-filtered with a kernel of 2 pixels radius in 3D to reduce noise and subsequently binarised by means of Otsu thresholding. "
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