Microstructural Analysis of Gas Transport Pathways in Red Chili Pepper by X-ray Computed Tomography

https://doi.org/10.22146/agritech.121929

Nurul Khomariyah(1), Nursigit Bintoro(2), Bayu Nugraha(3*)

(1) Department of Agricultural and Biosystem Engineering, Faculty of Agricultural Technology, Universitas Gadjah Mada, Jl. Flora No. 1, Bulaksumur, Yogyakarta 55281
(2) Department of Agricultural and Biosystem Engineering, Faculty of Agricultural Technology, Universitas Gadjah Mada, Jl. Flora No. 1, Bulaksumur, Yogyakarta 55281
(3) Department of Agricultural and Biosystem Engineering, Faculty of Agricultural Technology, Universitas Gadjah Mada, Jl. Flora No. 1, Bulaksumur, Yogyakarta 55281
(*) Corresponding Author

Abstract


Chili pepper (Capsicum frutescens L. cv. Ori 212) is a highly perishable horticultural commodity whose postharvest quality is influenced by internal gas transport processes. The efficiency of gas diffusion within fruit tissues depends on microstructural characteristics such as porosity, pore connectivity, and diffusion pathway tortuosity. This study aimed to characterize the three-dimensional microstructure and potential gas transport pathways in chili pepper 𝑆𝑆𝑑𝑑 π‘₯π‘₯ π‘Šπ‘Šπ‘‘π‘‘ π‘Žπ‘Žπ‘‘π‘‘π‘‘π‘‘π‘“π‘“π‘‘π‘‘π‘‘π‘‘π‘’π‘’π‘‘π‘‘ π‘‘π‘‘π‘‘π‘‘π‘Žπ‘Žπ‘“π‘“π‘’π‘’π‘‘π‘‘π‘‘π‘‘π‘‘π‘‘ (%) = tissues using X-ray Computed Tomography. Five fruits were scanned using a SkyScan 1173 micro-computed tomography system, and three anatomical regions, namely the pedicle, placenta, and pericarp, were analyzed. Three-dimensional image processing was performed to quantify porosity, pore connectivity, pore number, tortuosity, and effective oxygen diffusivity ( 𝑆𝑆 π‘₯π‘₯ π‘Šπ‘Š 𝐷𝐷𝑒𝑒𝑒𝑒𝑒𝑒,𝑂𝑂2 ). Significant differences in microstructural properties were observed among anatomical regions (p < 0.05).Β  The placenta exhibited the highest total porosity (58.58%), highest open porosity (58.54%), lowest tortuosity (1.27), and highest effective oxygen diffusivity (1.75 Γ— 10⁻⁢ mΒ² s⁻¹), indicating the presence of a highly interconnected pore network that favors gas diffusion. In contrast, the pericarp showed the lowest total porosity (14.81%), highest tortuosity (1.55), and lowest effective oxygen diffusivity (0.95 Γ— 10⁻⁢ mΒ² s⁻¹), reflecting a denser microstructure with more restricted gas transport pathways. Pore-size distribution analysis further revealed that the placenta contained fewer but larger interconnected pores, with pore volumes predominantly occurring in the 10 -4 -10 -3 mm 3 range, whereas the pericarp contained numerous smaller pores predominantly in the 10 -7 -10 -6 mm 3 range. These findings demonstrate that gas transport in chili pepper is spatially heterogeneous and associated with differences in pore connectivity, pore-size distribution, and diffusion pathway complexity. The study provides a structural basis for understanding internal oxygen transport and supports the development of improved postharvest storage and controlled-atmosphere management strategies for chili pepper.


Keywords


Chili pepper; microstructure; oxygen diffusivity; porosity; X-ray CT

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DOI: https://doi.org/10.22146/agritech.121929

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