Optimized drying of Thai Jinda chili peppers using a direct-heating air tray system: Enhancing efficiency and product quality
DOI:
https://doi.org/10.15282/ijame.23.2.2026.5.1024Keywords:
Thai Jinda chili pepper, Quality characteristic, Moisture diffusivity, Activation energy , Direct-heating air trays, Drying kineticAbstract
Since foods have naturally high amounts of water content, they are prone to microorganism growth and chemical decomposition. This research aims to explore the drying process of Thai Jinda chilies pepper (TJCPs) in the form of hot-air convection drying by means of a direct-heating perforated air tray (1.5×0.6×1.0 m3). The effects of different temperatures (55, 60, 65, 70, and 75 °C) and Reynolds numbers (20000, 30000, 40000, and 50000) were studied. As the results indicated, the increase in drying temperature and Reynolds number significantly accelerated the drying process of the samples. The optimal drying conditions were achieved by performing tests at 75 °C and Re = 50000; this led to the minimum drying time of about 6-7 hours without deteriorating the physical properties of TJCPs. The effective moisture diffusivity increased between 0.374×10-10 and 5.176×10-10 m²/s while the activation energy decreased in correlation with the airflow intensity. This can be explained by the enhancement of heat and mass transfer due to an intense airflow circulation, thinning of the thermal boundary layer, and efficient convective transport inside the drying chamber. It is concluded that the perforated air tray method is an effective way to enhance thermo-fluid drying of TJCPs.
References
[1] E. J. Rifna, M. Dwivedi, O. Chauhan, “Role of water activity in food preservation,” in Advances in Food Chemistry, 2022, pp. 39–64. https://doi.org/10.1007/978-981-19-4796-4_2
[2] O. Benedicta Adewoyin, “Pre-harvest and postharvest factors affecting quality and shelf life of harvested produce,” in New Advances in Postharvest Technology, İ. Kahramanoğlu Ed. London: IntechOpen, 2023. https://doi.org/10.5772/intechopen.111649
[3] S. Tepthanee, J. Taweekun, P. Vessakosol, “Application of passive technique to cocoa beans batch dryer and assessment of thin layer models,” International Journal of Automotive and Mechanical Engineering, vol. 21, no. 2, pp. 11398–11414, 2024. https://doi.org/10.15282/ijame.21.2.2024.17.0880
[4] M. S. Rana, A. N. M. A. Rahman, R. Ahmed, et al., “Design, fabrication, and performance evaluation of a food solar dryer,” AgriEngineering, vol. 6, no. 4, pp. 4506–4523, 2024. https://doi.org/10.3390/agriengineering6040257
[5] M. K. Rizalman, E. G. Moung, J. A. Dargham, Z. Jamain, N. M. Yaakub, S. Omatu, “Internet-of-things for smart dryers: Enablers, state of the arts, challenges, and solutions,” in 2022 IEEE International Conference on Artificial Intelligence in Engineering and Technology (IICAIET), 13–15 Sept 2022, pp. 1–6. https://doi.org/10.1109/IICAIET55139.2022.9936770
[6] A.-H. Mohammed, C. A. Komolafe, A. Simons, “Advances in solar drying technologies: A comprehensive review of designs, applications, and sustainability perspectives,” Solar Compass, vol. 17, 2026. https://doi.org/10.1016/j.solcom.2025.100153
[7] V. Shrivastava, P. Singh, N. Shrivastava, “A decade of progress in indirect solar drying: A review of systems for fruits, vegetables, and medicinal herbs (2015–2025),” Renewable and Sustainable Energy Reviews, vol. 226, 2026. https://doi.org/10.1016/j.rser.2025.116388
[8] L. Rajapaksha, D. M. C. C. Gunathilake, S. M. Pathirana, T. N. Fernando, “Reducing post-harvest losses in fruits and vegetables for ensuring food security – Case of Sri Lanka,” MOJ Food Processing & Technology, vol. 9, no. 1, pp. 7–16, 2021. https://doi.org/10.15406/mojfpt.2021.09.00255
[9] K. O. Obondo, L. M. Waswa, “The level of adoption of vegetable sun-drying technology in Teso South Sub County, Kenya,” Journal of the Kenya National Commission for UNESCO, vol. 5, no. 2, 2025. https://doi.org/10.62049/jkncu.v5i2.317
[10] J. F. Hinojosa, S. F. Moreno, V. M. Maytorena, “Low-temperature applications of phase change materials for energy storage: A descriptive review,” Energies, vol. 16, no. 7, 2023. https://doi.org/10.3390/en16073078
[11] D. P. García-Moreira, I. Moreno, E. C. López-Vidaña, “Controlled solar drying as a sustainable strategy to preserve color and minimize food waste,” AgriEngineering, vol. 7, no. 11, 2025. https://doi.org/10.3390/agriengineering7110392
[12] S. A. Siddiqui, İ. l. Ucak, S. Jain, et al., “Impact of drying on techno-functional and nutritional properties of food proteins and carbohydrates - A comprehensive review,” Drying Technology, vol. 42, no. 4, pp. 592–611, 2024. https://doi.org/10.1080/07373937.2024.2303580
[13] S. Lal, M. K. Mahatma, S. N. Saxena, et al., “Influence of drying methods on preservation of colour and quality attributes in celery (Apium graveolens L.) and dill (Anethum graveolens L.) leaves,” Applied Food Research, vol. 6, no. 1, 2026. https://doi.org/10.1016/j.afres.2026.101694
[14] T. Saengsuwan, N. Sujinda, “Integrated performance assessment of vacuum heat pump drying: a multi-criteria framework for energy-quality optimization in banana slice drying,” Sustainable Food Technology, vol. 4, no. 1, pp. 894–915, 2026. https://doi.org/10.1039/D5FB00546A
[15] O. Nnamchi, C. Tom, G. Akpan, et al., “Solar dryers: A review of mechanism, methods and critical analysis of transport models applicable in solar drying of product,” Green Energy and Resources, vol. 3, no. 2, 2025. https://doi.org/10.1016/j.gerr.2025.100118
[16] H. M. Elmatsani, S. J. Munarso, B. Benyamin, et al., “Global perspective on red chili drying: insights from two decades of research (2004–2023),” Frontiers in Sustainable Food Systems, vol. 8, 2024. https://doi.org/10.3389/fsufs.2024.1456938
[17] E. S. P. Yap, A. Uthairatanakij, N. Laohakunjit, P. Jitareerat, “Influence of hot air drying on capsaicinoids, phenolics, flavonoids and antioxidant activities of 'Super Hot' chilies,” PeerJ, vol. 10, p. e13423, 2022. https://doi.org/10.7717/peerj.13423
[18] A. Krzykowski, S. Rudy, R. Polak, et al., “Drying of Red Chili Pepper (Capsicum annuum L.): Process kinetics, color changes, carotenoid content and phenolic profile,” Molecules, vol. 29, no. 21, Oct 31 2024. https://doi.org/10.3390/molecules29215164
[19] F. Ajuebor, O. A. Aworanti, O. O. Agbede, S. E. Agarry, T. J. Afolabi, O. O. Ogunleye, “Drying process optimization and modelling the drying kinetics and quality attributes of dried chili pepper (Capsicum frutescens L.),” Trends in Sciences, vol. 19, no. 17, 2022. https://doi.org/10.48048/tis.2022.5752
[20] J. O. Ojediran, C. E. Okonkwo, A. F. Olaniran, et al., “Hot air convective drying of hog plum fruit (Spondias mombin): effects of physical and edible-oil-aided chemical pretreatments on drying and quality characteristics,” Heliyon, vol. 7, no. 11, p. e08312, Nov 2021. https://doi.org/10.1016/j.heliyon.2021.e08312
[21] L. A. Espinoza-Espinoza, C. E. Juárez-Ojeda, L. A. Ruiz-Flores, L. A. Moreno-Quispe, M. S. Anaya-Palacios, H. Cárdenas-Quintana, “Influence of convection drying with hot air on the physicochemical and phytochemical properties of green banana flour (Musa cavendish),” Frontiers in Sustainable Food Systems, vol. 7, 2023. https://doi.org/10.3389/fsufs.2023.1204349
[22] R. Bai, J. Sun, X. Qiao, Z. Zheng, M. Li, B. Zhang, “Hot air convective drying of ginger slices: drying behaviour, quality characteristics, optimisation of parameters, and volatile fingerprints analysis,” Foods, vol. 12, no. 6, 2023. https://doi.org/10.3390/foods12061283
[23] Z. Zheng, S. Wang, C. Zhang, et al., “Hot air impingement drying enhanced drying characteristics and quality attributes of Ophiopogonis Radix,” Foods, vol. 12, no. 7, 2023. https://doi.org/10.3390/foods12071441
[24] E. M. Goncalves, N. Pereira, M. Silva, et al., “Influence of air-drying conditions on quality, bioactive composition and sensorial attributes of sweet potato chips,” Foods, vol. 12, no. 6, 2023. https://doi.org/10.3390/foods12061198
[25] S. Kaleemullah, R. Kailappan, “Geometric and morphometric properties of chillies,” International Journal of Food Properties, vol. 6, no. 3, pp. 481–498, 2007. https://doi.org/10.1081/JFP-120021454
[26] Y. Keawsuntia, “Experimental investigation of active solar dryer for drying of chili,” Advanced Materials Research, vol. 953-954, pp. 16–19, 2014. https://doi.org/10.4028/www.scientific.net/AMR.953-954.16
[27] M. Wae-hayee, K. Yeranee, W. Suksuwan, A. Alimalbari, S. Sae-ung, C. Nuntadusit, “Heat transfer enhancement in rotary drum dryer by incorporating jet impingement to accelerate drying rate,” Drying Technology, vol. 39, no. 10, pp. 1314–1324, 2020.
[28] Ministry of Agriculture and Cooperatives, “Thai Agricultural Standard: Dried Chilli (TAS 3001-2010),” National Bureau of Agricultural Commodity and Food Standards, 2010 (in Thai). https://doi.org/10.1080/07373937.2020.1742150
[29] Association of Official Analytical Chemists Inc., “AOAC: Official Methods of Analysis (Volume 1),” 1990.
[30] İ. Doymaz, F. Kocayigit, “Effect of pre-treatments on drying, rehydration, and color characteristics of red pepper (‘Charliston’ variety),” Food Science and Biotechnology, vol. 21, no. 4, pp. 1013–1022, 2012. https://doi.org/10.1007/s10068-012-0132-z
[31] L. Xie, A. S. Mujumdar, X.-M. Fang, et al., “Far-infrared radiation heating assisted pulsed vacuum drying (FIR-PVD) of wolfberry ( Lycium barbarum L.): Effects on drying kinetics and quality attributes,” Food and Bioproducts Processing, vol. 102, pp. 320–331, 2017. https://doi.org/10.1016/j.fbp.2017.01.012
[32] M. Aghbashlo, M. H. kianmehr, H. Samimi-Akhijahani, “Influence of drying conditions on the effective moisture diffusivity, energy of activation and energy consumption during the thin-layer drying of berberis fruit (Berberidaceae),” Energy Conversion and Management, vol. 49, no. 10, pp. 2865–2871, 2008. https://doi.org/10.1016/j.enconman.2008.03.009
[33] R. J. Moffat, “Describing the uncertainties in experimental results,” Experimental Thermal and Fluid Science, vol. 1, no. 1, pp. 3–17, 1988. https://doi.org/10.1016/0894-1777(88)90043-X
[34] A. K. Bhardwaj, R. Kumar, R. Chauhan, S. Kumar, “Experimental investigation and performance evaluation of a novel solar dryer integrated with a combination of SHS and PCM for drying chilli in the Himalayan region,” Thermal Science and Engineering Progress, vol. 20, 2020. https://doi.org/10.1016/j.tsep.2020.100713
[35] L.-Z. Deng, X.-H. Yang, A. S. Mujumdar, et al., “Red pepper (Capsicum annuum L.) drying: Effects of different drying methods on drying kinetics, physicochemical properties, antioxidant capacity, and microstructure,” Drying Technology, vol. 36, no. 8, pp. 893–907, 2017. https://doi.org/10.1080/07373937.2017.1361439
[36] K. Di Scala, G. Crapiste, “Drying kinetics and quality changes during drying of red pepper,” LWT - Food Science and Technology, vol. 41, no. 5, pp. 789–795, 2008. https://doi.org/10.1016/j.lwt.2007.06.007
[37] S. Kaleemullah, R. Kailappan, “Modelling of thin-layer drying kinetics of red chillies,” Journal of Food Engineering, vol. 76, no. 4, pp. 531–537, 2006. https://doi.org/10.1016/j.jfoodeng.2005.05.049
[38] H.-Y. Ju, C.-L. Law, X.-M. Fang, H.-W. Xiao, Y.-H. Liu, Z.-J. Gao, “Drying kinetics and evolution of the sample's core temperature and moisture distribution of yam slices (Dioscorea alataL.) during convective hot-air drying,” Drying Technology, vol. 34, no. 11, pp. 1297–1306, 2015. https://doi.org/10.1080/07373937.2015.1105814
[39] H.-W. Xiao, C.-L. Pang, L.-H. Wang, J.-W. Bai, W.-X. Yang, Z.-J. Gao, “Drying kinetics and quality of Monukka seedless grapes dried in an air-impingement jet dryer,” Biosystems Engineering, vol. 105, no. 2, pp. 233–240, 2010. https://doi.org/10.1016/j.biosystemseng.2009.11.001
[40] J.-W. Dai, J.-Q. Rao, D. Wang, et al., “Process-based drying temperature and humidity integration control enhances drying kinetics of apricot halves,” Drying Technology, vol. 33, no. 3, pp. 365–376, 2015. https://doi.org/10.1080/07373937.2014.954667
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