PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

This review paper explores the utilization of supercritical carbon dioxide (SC-CO2) extraction to isolate citronella oil, delving into its multifaceted dimensions, including process optimization, product quality enhancement, and diverse potential applications. Citronella oil, renowned for its myriad bioactive compounds with demonstrated health benefits, is a coveted essential oil in the pharmaceutical, cosmetics, and food industries. The transition from traditional extraction techniques to SC-CO2 extraction presents a paradigm shift due to its manifold advantages, such as heightened yield rates, expedited extraction durations, and elevated product quality. However, the efficacy of SC-CO2 extraction is intricately interwoven with an array of parameters encompassing pressure, temperature, flow rate, particle size, and co-solvent ratios. Accordingly, meticulous process optimization is indispensable in achieving the desired product quality while maximizing yield. Furthermore, the paper explores the extensive spectrum of potential applications for citronella oil, extending its reach into formulations with antimicrobial, insecticidal, and antioxidant properties. These applications underscore the versatility and commercial appeal of citronella oil. The review establishes SC-CO2 extraction of citronella oil as a promising and sustainable alternative to conventional extraction methodologies, offering myriad applications across the pharmaceutical, cosmetics, and food sectors. This scholarly work provides valuable insights into the intricacies of process optimization and product quality. It outlines future perspectives and avenues for further exploration in SC-CO2 extraction of citronella oil.

• Ahmad, T., Masoodi, F., Rather, S. A., Wani, S., & Gull, A. (2019). Supercritical fluid extraction: A review. Journal of Biological and Chemical Chronicles, 5(1), 114-122.

• Akkarawatkhoosith, N., Kaewchada, A., & Jaree, A. (2019). Enhancement of continuous supercritical biodiesel production: influence of co-solvent types. Energy Procedia, 156, 48-52. https://doi.org/10.1016/j.egypro.2018.11.085

• Alesaeidi, S., & Miraj, S. (2016). A systematic review of anti-malarial properties, immunosuppressive properties, anti-inflammatory properties, and anti-cancer properties of Artemisia annua. Electronic Physician, 8(10), Article 3150. https://doi.org/10.19082/3150

• Ali, B., Al-Wabel, N. A., Shams, S., Ahamad, A., Khan, S. A., & Anwar, F. (2015). Essential oils used in aromatherapy: A systemic review. Asian Pacific Journal of Tropical Biomedicine, 5(8), 601-611. https://doi.org/10.1016/j.apjtb.2015.05.007

• Ammar, R. B. (2023). Potential effects of geraniol on cancer and inflammation-related diseases: A review of the recent research findings. Molecules, 28(9), Article 3669. https://doi.org/10.3390/molecules28093669

• Anandakumar, P., Kamaraj, S., & Vanitha, M. K. (2021). D‐limonene: A multifunctional compound with potent therapeutic effects. Journal of Food Biochemistry, 45(1), Article e13566. https://doi.org/10.1111/jfbc.13566

• Aprodu, I., Milea, Ș. A., Enachi, E., Râpeanu, G., Bahrim, G. E., & Stănciuc, N. (2020). Thermal degradation kinetics of anthocyanins extracted from purple maize flour extract and the effect of heating on selected biological functionality. Foods, 9(11), Article 1593. https://doi.org/10.3390/foods9111593

• Argun, M. E., Argun, M. Ş., Arslan, F. N., Nas, B., Ates, H., Tongur, S., & Cakmakcı, O. (2022). Recovery of valuable compounds from orange processing wastes using supercritical carbon dioxide extraction. Journal of Cleaner Production, 375, Article 134169. https://doi.org/10.1016/j.jclepro.2022.134169

• Arsad, N. H., Putra, N. R., Idham, Z., Norodin, N. S. M., Yunus, M. A. C., & Aziz, A. H. A. (2023). Solubilization of eugenol from Piper betle leaves to supercritical carbon dioxide: Experimental and modelling. Results in Engineering, 17, Article 100914. https://doi.org/10.1016/j.rineng.2023.100914

• Arumugham, T., AlYammahi, J., Rambabu, K., Hassan, S. W., & Banat, F. (2022). Supercritical CO2 pretreatment of date fruit biomass for enhanced recovery of fruit sugars. Sustainable Energy Technologies and Assessments, 52, Article 102231. https://doi.org/10.1016/j.seta.2022.102231

• Arumugham, T., K, R., Hasan, S. W., Show, P. L., Rinklebe, J., & Banat, F. (2021). Supercritical carbon dioxide extraction of plant phytochemicals for biological and environmental applications - A review. Chemosphere, 271, Article 129525. https://doi.org/10.1016/j.chemosphere.2020.129525

• Aziz, Z. A. A., Ahmad, A., Setapar, S. H. M., Karakucuk, A., Azim, M. M., Lokhat, D., Rafatullah, M., Ganash, M., Kamal, M. A., & Ashraf, G. M. (2018). Essential oils: Extraction techniques, pharmaceutical and therapeutic potential - A review. Current Drug Metabolism, 19(13), 1100-1110. https://doi.org/10.2174/1389200219666180723144850

• Aziz, A. H. A., Idrus, N. F. M., Putra, N. R., Awang, M. A., Idham, Z., Mamat, H., & Yunus, M. A. C. (2022). Solubility of rosmarinic acid in supercritical carbon dioxide extraction from Orthosiphon stamineus leaves. ChemEngineering, 6(4), Article 59. https://doi.org/10.3390/chemengineering6040059

• Aziz, A. H. A., Putra, N. R., Kong, H., & Yunus, M. A. C. (2020). Supercritical carbon dioxide extraction of sinensetin, isosinensetin, and rosmarinic acid from Orthosiphon stamineus leaves: Optimization and modeling. Arabian Journal for Science and Engineering, 45(9), 7467-7476. https://doi.org/10.1007/s13369-020-04584-6

• Aziz, A. H. A., Putra, N. R., Zaini, A. S., Idham, Z., Ahmad, M. Z., & Yunus, M. A. C. (2021). Solubility of sinensetin and isosinensetin from Cat’s Whiskers (Orthosiphon stamineus) leaves in ethanol-assisted supercritical carbon dioxide extraction: Experimental and modeling. Chemical Papers, 75(12), 6557-6563. https://doi.org/10.1007/s11696-021-01822-5

• Aziz, A. H. A., Rizkiyah, D. N., Qomariyah, L., Irianto, I., Yunus, M. A. C., & Putra, N. R. (2023). Unlocking the full potential of clove (Syzygium aromaticum) spice: An overview of extraction techniques, bioactivity, and future opportunities in the food and beverage industry. Processes, 11(8), Article 2453. https://doi.org/10.3390/pr11082453

• Bakkali, F., Averbeck, S., Averbeck, D., & Idaomar, M. (2008). Biological effects of essential oils - A review. Food and Chemical Toxicology, 46(2), 446-475. https://doi.org/10.1016/j.fct.2007.09.106

• Barbas, L. A. L., Hamoy, M., de Mello, V. J., Barbosa, R. P. M., de Lima, H. S. T., Torres, M. F., do Nascimento, L. A. S., da Silva, J. K. D. R., Andrade, E. H. D. A., & Gomes, M. R. F. (2017). Essential oil of citronella modulates electrophysiological responses in tambaqui Colossoma macropomum: A new anaesthetic for use in fish. Aquaculture, 479, 60-68. https://doi.org/10.1016/j.aquaculture.2017.05.027

• Bell, K. L. (2012). Holistic aromatherapy for animals: A comprehensive guide to the use of essential oils & hydrosols with animals. Simon and Schuster.

• Benelli, P., Riehl, C. A. S., Smânia, A., Smânia, E. F. A., & Ferreira, S. R. S. (2010). Bioactive extracts of orange (Citrus sinensis L. Osbeck) pomace obtained by SFE and low pressure techniques: Mathematical modeling and extract composition. The Journal of Supercritical Fluids, 55(1), 132-141. https://doi.org/10.1016/j.supflu.2010.08.015

• Byun, H. S. (2020). Co-solvent concentration influence of two-and three-component systems on the high pressure cloud-point behavior for the poly (vinyl stearate) under supercritical CO2. Journal of Industrial and Engineering Chemistry, 90, 76-84. https://doi.org/10.1016/j.jiec.2020.06.024

• Capuzzo, A., Maffei, M. E., & Occhipinti, A. (2013). Supercritical fluid extraction of plant flavors and fragrances. Molecules, 18(6), 7194-7238. https://doi.org/10.3390/molecules18067194

• Carvalho, I. T., Estevinho, B. N., & Santos, L. (2016). Application of microencapsulated essential oils in cosmetic and personal healthcare products - A review. International Journal of Cosmetic Science, 38(2), 109-119. https://doi.org/10.1111/ics.12232

• Cassel, E., & Vargas, R. M. (2006). Experiments and modeling of the Cymbopogon winterianus essential oil extraction by steam distillation. Journal of the Mexican Chemical Society, 50(3), 126-129.

• Chai, Y. H., Yusup, S., Kadir, W. N. A., Wong, C. Y., Rosli, S. S., Ruslan, M. S. H., Chin, B. L. F., & Yiin, C. L. (2020). Valorization of tropical biomass waste by supercritical fluid extraction technology. Sustainability, 13(1), Article 233. https://doi.org/10.3390/su13010233

• Chemat, F., Vian, M. A., Fabiano-Tixier, A.-S., Nutrizio, M., Jambrak, A. R., Munekata, P. E. S., Lorenzo, J. M., Barba, F. J., Binello, A., & Cravotto, G. (2020). A review of sustainable and intensified techniques for extraction of food and natural products. Green Chemistry, 22(8), 2325-2353. https://doi.org/10.1039/C9GC03878G

• Chen, W., & Viljoen, A. (2010). Geraniol - A review of a commercially important fragrance material. South African Journal of Botany, 76(4), 643-651. https://doi.org/10.1016/j.sajb.2010.05.008

• Daneshyan, S., & Sodeifian, G. (2022). Synthesis of cyclic polystyrene in supercritical carbon dioxide green solvent. The Journal of Supercritical Fluids, 188, Article 105679. https://doi.org/10.1016/j.supflu.2022.105679

• Daud, N. M., Putra, N. R., Jamaludin, R., Norodin, N. S. M., Sarkawi, N. S., Hamzah, M. H. S., Nasir, H. M., Zaidel, D. N. A., Yunus, M. A. C., & Salleh, L. M. (2022). Valorisation of plant seed as natural bioactive compounds by various extraction methods: A review. Trends in Food Science & Technology, 119, 201-214. https://doi.org/10.1016/j.tifs.2021.12.010

• de Melo, M. M., Carius, B., Simões, M. M., Portugal, I., Saraiva, J., & Silva, C. M. (2020). Supercritical CO2 extraction of V. vinifera leaves: Influence of cosolvents and particle size on removal kinetics and selectivity to target compounds. The Journal of Supercritical Fluids, 165, Article 104959. https://doi.org/10.1016/j.supflu.2020.104959

• de Oliveira, M. S., Silva, S. G., da Cruz, J. N., Ortiz, E., da Costa, W. A., Bezerra, F. W. F., Cunha, V. M. B., Cordeiro, R. M., Neto, A. M. D. J. C., Andrade, E. H. D. A., & Junior, R. N. D. C. (2019). Supercritical CO2 application in essential oil extraction. In R. M. Inamuddin & A. M. Asiri (Eds.), Industrial Applications of Green Solvents (Volume 2: pp. 1-28). Material Research Foundations. https://doi.org/10.21741/97816449000314-1

• del Valle, J. M. (2015). Extraction of natural compounds using supercritical CO2: Going from the laboratory to the industrial application. The Journal of Supercritical Fluids, 96, 180-199. https://doi.org/10.1016/j.supflu.2014.10.001

• Devi, M. A., Sahoo, D., Singh, T. B., & Rajashekar, Y. (2021). Antifungal activity and volatile organic compounds analysis of essential oils from Cymbopogon species using solid-phase microextraction-gas chromatography-mass spectrometry. Journal of Agriculture and Food Research, 3, Article 100110. https://doi.org/10.1016/j.jafr.2021.100110

• Dhakane-Lad, J., & Kar, A. (2021). Supercritical CO2 extraction of lycopene from pink grapefruit (Citrus paradise Macfad) and its degradation studies during storage. Food Chemistry, 361, Article 130113. https://doi.org/10.1016/j.foodchem.2021.130113

• Dhara, O., Rani, K. P., & Chakrabarti, P. P. (2022). Supercritical carbon dioxide extraction of vegetable oils: Retrospective and prospects. European Journal of Lipid Science and Technology, 124(8), Article 2200006. https://doi.org/10.1002/ejlt.202200006

• Dimić, I., Pezo, L., Rakić, D., Teslić, N., Zeković, Z., & Pavlić, B. (2021). Supercritical fluid extraction kinetics of cherry seed oil: kinetics modeling and ANN optimization. Foods, 10(7), Article 1513. https://doi.org/10.3390/foods10071513

• El-Kholany, E. A. (2016). Utilization of essential oils from citronella and geranium as natural preservative in mayonnaise. International Journal of Microbiology and Biotechnology, 1(1), 49-59.

• Ganjewala, D. (2009). Cymbopogon essential oils: Chemical compositions and bioactivities. International Journal of Essential Oil Therapeutics, 3(2-3), 56-65.

• Gavahian, M., Lee, Y. T., & Chu, Y. H. (2018). Ohmic-assisted hydrodistillation of citronella oil from Taiwanese citronella grass: Impacts on the essential oil and extraction medium. Innovative Food Science & Emerging Technologies, 48, 33-41. https://doi.org/10.1016/j.ifset.2018.05.015

• Golmohammadi, M., Borghei, A., Zenouzi, A., Ashrafi, N., & Taherzadeh, M. J. (2018). Optimization of essential oil extraction from orange peels using steam explosion. Heliyon, 4(11), Article e00893. https://doi.org/10.1016/j.heliyon.2018. e00893

• Guedes, A. R., de Souza, A. R. C., Zanoelo, E. F., & Corazza, M. L. (2018). Extraction of citronella grass solutes with supercritical CO2, compressed propane and ethanol as cosolvent: Kinetics modeling and total phenolic assessment. The Journal of Supercritical Fluids, 137, 16-22. https://doi.org/10.1016/j.supflu.2018.03.003

• Hamzah, M. H., Man, H. C., Abidin, Z. Z., & Jamaludin, H. (2014). Comparison of citronella oil extraction methods from cymbopogon nardus grass by ohmic-heated hydro-distillation, hydro-distillation, and steam distillation. BioResources, 9(1), 256-272.

• Hanif, M. A., Nisar, S., Khan, G. S., Mushtaq, Z., & Zubair, M. (2019). Essential oils. In S. Malik (Ed.), Essential Oil Research: Trends in Biosynthesis, Analytics, Industrial Applications and Biotechnological Production (pp. 3-17). Springer. https://doi.org/10.1007/978-3-030-16546-8_1

• Happy, A. A., Jahan, F., & Momen, M. A. (2021). Essential oils: Magical ingredients for skin care. Journal of Plant Sciences, 9(2), Article 54.

• Hayyan, A., Samyudia, A. V., Hashim, M. A., Hizaddin, H. F., Ali, E., Hadj-Kali, M. K., Aldeehani, A. K., Alkandari, K. H., Etigany, H. T., Alajmi, F. D. H., Alhumaydhi, F. A., Aljohari, A. S. M., Zulkifli, M. Y., Halilu, A., & Yeow, A. T. H. (2022). Application of deep eutectic solvent as novel co-solvent for oil extraction from flaxseed using sonoenergy. Industrial Crops and Products, 176, Article 114242. https://doi.org/10.1016/j.indcrop.2021.114242

• Hsu, W. S., Yen, J. H., & Wang, Y. S. (2013). Formulas of components of citronella oil against mosquitoes (Aedes aegypti). Journal of Environmental Science and Health, Part B, 48(11), 1014-1019. https://doi.org/10.1080/03601234.2013.816613

• Idham, Z., Putra, N. R., Nasir, H., Yian, L. N., Idrus, N. F. M., & Yunus, M. A. C. (2021). Extraction and solubility modeling of anthocyanins rich extract from hibiscus sabdariffa l. using supercritical carbon dioxide. Malaysian Journal of Fundamental and Applied Sciences, 17(6), 720-730.

• Isman, M. B., Miresmailli, S., & Machial, C. (2011). Commercial opportunities for pesticides based on plant essential oils in agriculture, industry and consumer products. Phytochemistry Reviews, 10, 197-204. https://doi.org/10.1007/s11101-010-9170-4

• Jha, A. K., & Sit, N. (2022). Extraction of bioactive compounds from plant materials using combination of various novel methods: A review. Trends in Food Science & Technology, 119, 579-591. https://doi.org/10.1016/j.tifs.2021.11.019

• Kaur, H., Bhardwaj, U., Kaur, R., & Kaur, H. (2021). Chemical composition and antifungal potential of citronella (Cymbopogon nardus) leaves essential oil and its major compounds. Journal of Essential Oil Bearing Plants, 24(3), 571-581. https://doi.org/10.1080/0972060X.2021.1942231

• Khan, M. F., & Dwivedi, A. K. (2018). A review on techniques available for the extraction of essential oils from various plants. International Research Journal of Engineering and Technology, 5(5), 5-8.

• Kim, D. S., & Lim, S. B. (2020). Kinetic study of subcritical water extraction of flavonoids from citrus unshiu peel. Separation and Purification Technology, 250, Article 117259. https://doi.org/10.1016/j.seppur.2020.117259

• Klein, E. J., Nathia-Neves, G., Vardanega, R., Meireles, M. A. A., da Silva, E. A., & Vieira, M. G. A. (2019). Supercritical CO2 extraction of α-/β-amyrin from uvaia (Eugenia pyriformis Cambess.): Effects of pressure and co-solvent addition. The Journal of Supercritical Fluids, 153, Article 104595. https://doi.org/10.1016/j.supflu.2019.104595

• Leila, M., Ratiba, D., & Al-Marzouqi, A. H. (2022). Experimental and mathematical modelling data of green process of essential oil extraction: Supercritical CO2 extraction. Materials Today: Proceedings, 49, 1023-1029. https://doi.org/10.1016/j.matpr.2021.08.125

• Li, C., Luo, Y., Zhang, W., Cai, Q., Wu, X., Tan, Z., Chen, R., Chen, Z., Wang, S., & Zhang, L. (2021). A comparative study on chemical compositions and biological activities of four essential oils: Cymbopogon citratus (DC.) Stapf, Cinnamomum cassia (L.) Presl, Salvia japonica Thunb. and Rosa rugosa Thunb. Journal of Ethnopharmacology, 280, Article 114472. https://doi.org/10.1016/j.jep.2021.114472

• Lim, S. F., Hamdan, A., David Chua, S. N., & Lim, B. H. (2021). Comparison and optimization of conventional and ultrasound‐assisted solvent extraction for synthetization of lemongrass (Cymbopogon)‐infused cooking oil. Food Science & Nutrition, 9(5), 2722-2732. https://doi.org/10.1002/fsn3.2234

• Machado, N. D., Mosquera, J. E., Martini, R. E., Goñi, M. L., & Gañán, N. A. (2022). Supercritical CO2-assisted impregnation of cellulose microparticles with R-carvone: Effect of process variables on impregnation yield. The Journal of Supercritical Fluids, 188, Article 105671. https://doi.org/10.1016/j.supflu.2022.105671

• Machmudah, S., Sulaswatty, A., Sasaki, M., Goto, M., & Hirose, T. (2006). Supercritical CO2 extraction of nutmeg oil: Experiments and modeling. The Journal of Supercritical Fluids, 39(1), 30-39. https://doi.org/10.1016/j.supflu.2006.01.007

• Manaf, M. A., Mustapa, A. N., & Mustapa, K. (2013). Supercritical fluid extraction of Citronella oil from Cymbopogon nardus and its optimization. [Paper presentation]. IEEE Business Engineering and Industrial Applications Colloquium (BEIAC), Langkawi, Malaysia. https://doi.org/10.1109/BEIAC.2013.6560229

• Manosroi, J., Dhumtanom, P., & Manosroi, A. (2006). Anti-proliferative activity of essential oil extracted from Thai medicinal plants on KB and P388 cell lines. Cancer Letters, 235(1), 114-120. https://doi.org/10.1016/j.canlet.2005.04.021

• Marcus, Y. (2018). Extraction by subcritical and supercritical water, methanol, ethanol and their mixtures. Separations, 5(1), Article 4. https://doi.org/10.3390/separations5010004

• Moges, A., Barik, C. R., Sahoo, L., & Goud, V. V. (2022). Optimization of polyphenol extraction from Hippophae salicifolia D. Don leaf using supercritical CO2 by response surface methodology. 3 Biotech, 12(11), Article 292. https://doi.org/10.1007/s13205-022-03358-1

• Mohd‐Nasir, H., Putra, N. R., Chuo, S. C., Daud, N. M., Hartati, H., Bakeri, N., Ruslan, M. S. H., Mohd-Setapar, S. H., Ahmad, A., & Salleh, L. M. (2021). Optimization of the supercritical carbon dioxide extraction of Quercus infectoria galls extracts and its bioactivities. Journal of Food Processing and Preservation, 45(2), Article e15156. https://doi.org/10.1111/jfpp.15156

• Muhammad, S., Khalil, H. P. S. A., Hamid, S. A., Danish, M., Marwan, M., Yunardi, Y., Abdullah, C. K., Faisal, M., & Yahya, E. B. (2022). Characterization of bioactive compounds from patchouli extracted via supercritical carbon dioxide (SC-CO2) extraction. Molecules, 27(18), Article 6025. https://doi.org/10.3390/molecules27186025

• Nakahara, K., Alzoreky, N. S., Yoshihashi, T., Nguyen, H. T., & Trakoontivakorn, G. (2013). Chemical composition and antifungal activity of essential oil from Cymbopogon nardus (citronella grass). Japan Agricultural Research Quarterly: JARQ, 37(4), 249-252. https://doi.org/10.6090/jarq.37.249

• Neequaye, K., Adonu, R., & Mensah, D. O. A. (2017). Production of cake using lemon grass as flavouring agent. American Based Research Journal, 6(11), 48-60.

• Nollet, L. M., & Rathore, H. S. (2017). Essential oil mixtures for pest control. In Green Pesticides Handbook (pp. 509-522). CRC Press.

• Odunlami, O. A., Vershima, D. A., Oladimeji, T. E., Nkongho, S., Ogunlade, S. K., & Fakinle, B. S. (2022). Advanced techniques for the capturing and separation of CO2 - A review. Results in Engineering, 15, Article 100512. https://doi.org/10.1016/j.rineng.2022.100512

• Okpo, S. O., & Otaraku, I. J. (2020). Modelling of soxhlet extraction of lemongrass oil. International Journal of Chemical Engineering Research, 7(2), 24-29.

• Ongkasin, K., Sauceau, M., Masmoudi, Y., Fages, J., & Badens, E. (2019). Solubility of cefuroxime axetil in supercritical CO2: Measurement and modeling. The Journal of Supercritical Fluids, 152, Article 104498. https://doi.org/10.1016/j.supflu.2019.03.010

• Park, H. S., Choi, H. K., Lee, S. J., Park, K. W., Choi, S. G., & Kim, K. H. (2007). Effect of mass transfer on the removal of caffeine from green tea by supercritical carbon dioxide. The Journal of Supercritical Fluids, 42(2), 205-211. https://doi.org/10.1016/j.supflu.2007.03.002

• Pavlić, B., Pezo, L., Marić, B., Tukuljac, L. P., Zeković, Z., Solarov, M. B., & Teslić, N. (2020). Supercritical fluid extraction of raspberry seed oil: Experiments and modelling. The Journal of Supercritical Fluids, 157, Article 104687. https://doi.org/10.1016/j.supflu.2019.104687

• Peng, W. L., Mohd-Nasir, H., Setapar, S. H. M., Ahmad, A., & Lokhat, D. (2020). Optimization of process variables using response surface methodology for tocopherol extraction from Roselle seed oil by supercritical carbon dioxide. Industrial Crops and Products, 143, Article 111886. https://doi.org/10.1016/j.indcrop.2019.111886

• Pohlit, A. M., Lopes, N. P., Gama, R. A., Tadei, W. P., & de Andrade Neto, V. F. (2011). Patent literature on mosquito repellent inventions which contain plant essential oils - A review. Planta Medica, 77(06), 598-617. https://doi.org/10.1055/s-0030-1270723

• Putra, N. R., Rizkiyah, D. N., Aziz, A. H. A., Yunus, M. A., Veza, I., Harny, I., & Tirta, A. (2023). Waste to wealth of apple pomace valorization by past and current extraction processes: A review. Sustainability, 15(1), Article 830. https://doi.org/10.3390/su15010830

• Putra, N. R., Rizkiyah, D. N., Aziz, A. H. A., Mamat, H., Jusoh, W. M. S. W., Idham, Z., Yunus, M. A. C., & Irianto, I. (2023). Influence of particle size in supercritical carbon dioxide extraction of roselle (Hibiscus sabdariffa) on bioactive compound recovery, extraction rate, diffusivity, and solubility. Scientific Reports, 13(1), Article 10871. https://doi.org/10.1038/s41598-023-32181-8

• Putra, N. R., Rizkiyah, D. N., Idham, Z., Zaini, M. A. A., Yunus, M. A. C., & Aziz, A. H. A. (2023). Optimization and solubilization of interest compounds from roselle in subcritical ethanol extraction (SEE). Alexandria Engineering Journal, 65, 59-74. https://doi.org/10.1016/j.aej.2022.09.037

• Putra, N. R., Rizkiyah, D. N., Idham, Z., Jumakir, J., Waluyo, W., Faizal, A. N. M., & Yunus, M. A. C. (2022). A new solubility model for competing effects of three solvents: Water, ethanol, and supercritical carbon dioxide. Separation Science and Technology, 57(14), 2269-2275. https://doi.org/10.1080/01496395.2022.2045317

• Putra, N. R., Rizkiyah, D. N., Zaini, A. S., Machmudah, S., & Yunus, M. A. C. (2021). Solubility of catechin and epicatechin from Arachis Hypogea skins wastes by using supercritical carbon dioxide-ethanol and its optimization. Journal of Food Measurement and Characterization, 15(2), 2031-2038. https://doi.org/10.1007/s11694-020-00797-3

• Putra, N. R., Aziz, A. H. A., Idham, Z., Ruslan, M. S. H., & Yunus, M. A. C. (2018). Diffusivity optimization of supercritical carbon dioxide extraction with co-solvent-ethanol from peanut skin. Malaysian Journal of Fundamental and Applied Sciences, 14(1), 9-14.

• Putra, N. R., Rizkiyah, D. N., Zaini, A. S., Yunus, M. A. C., Machmudah, S., Idham, Z. B., & Ruslan, M. S. H. (2018). Effect of particle size on yield extract and antioxidant activity of peanut skin using modified supercritical carbon dioxide and soxhlet extraction. Journal of Food Processing and Preservation, 42(8), Article e13689. https://doi.org/10.1111/jfpp.13689

• Ramezani, N., Raji, F., Rezakazemi, M., & Younas, M. (2020). Juglone extraction from walnut (Juglans regia L.) green husk by supercritical CO2: Process optimization using Taguchi method. Journal of Environmental Chemical Engineering, 8(3), Article 103776. https://doi.org/10.1016/j.jece.2020.103776

• Ribeiro, J., Lopes, H., Queijo, L., & Figueiredo, D. (2017). Optimization of cutting parameters to minimize the surface roughness in the end milling process using the Taguchi method. Periodica Polytechnica Mechanical Engineering, 61(1), 30-35. https://doi.org/10.3311/PPme.9114

• Rizkiyah, D. N., Putra, N. R., Idham, Z., Aziz, A. H. A., Che Yunus, M. A., Veza, I., Irianto, Mamah, S. C., & Qomariyah, L. (2023). Recovery of anthocyanins from hibiscus sabdariffa L. Using a combination of supercritical carbon dioxide extraction and subcritical water extraction. Processes, 11(3), Article 751. https://doi.org/10.3390/pr11030751

• Rizkiyah, D. N., Putra, N. R., Idham, Z., Che Yunus, M. A., Veza, I., Harny, I., Syahlani, N., Aziz, A. H. A. (2022). Optimization of red pigment anthocyanin recovery from hibiscus sabdariffa by subcritical water extraction. Processes, 10(12), Article 2635. https://doi.org/10.3390/pr10122635

• Rosli, N. R., Daud, W. R. W., Md Jahim, J., & Markom, M. (2007). Supercritical fluid extraction of ctronella (Cymbopogon nardus) essential oil: Modelling the effects of varying operating temperature and pressure. Malaysian Journal of Chemical Engineering, 1, 143-152.

• Salaria, D., Rolta, R., Sharma, N., Dev, K., Sourirajan, A., & Kumar, V. (2020). In silico and in vitro evaluation of the anti-inflammatory and antioxidant potential of Cymbopogon citratus from North-western Himalayas. BioRxiv. https://doi.org/10.1101/2020.05.31.124982

• Salea, R., Hiendrawan, S., Subroto, E., Veriansyah, B., & Tjandrawinata, R. R. (2018). Supercritical carbon dioxide extraction of citronella oil from cymbopogon winterianus using taguchi orthogonal array design. International Journal of Applied Pharmaceutics, 10(6), 147-151. https://doi.org/10.22159/ijap.2018v10i6.28880

• Sarah, M., Ardiansyah, D., Misran, E., & Madinah, I. (2023). Extraction of citronella oil from lemongrass (Cymbopogon winterianus) by sequential ultrasonic and microwave-assisted hydro-distillation. Alexandria Engineering Journal, 70, 569-583. https://doi.org/10.1016/j.aej.2023.03.019

• Sathasivam, R., Muthuraman, M. S., & Park, S. U. (2022). Intensification of supercritical fluid in the extraction of flavonoids: A comprehensive review. Physiological and Molecular Plant Pathology, 118, Article 101815. https://doi.org/10.1016/j.pmpp.2022.101815

• Silva, C. F., Moura, F. C., Mendes, M. F., & Pessoa, F. L. P. (2011). Extraction of citronella (Cymbopogon nardus) essential oil using supercritical CO2: Experimental data and mathematical modeling. Brazilian Journal of Chemical Engineering, 28(2), 343-350. https://doi.org/10.1590/S0104-66322011000200019

• Silva, S. G., de Oliveira, M. S., Cruz, J. N., da Costa, W. A., da Silva, S. H. M., Maia, A. A. B., de Sousa, R. L., Junior R. F. C., & de Aguiar Andrade, E. H. (2021). Supercritical CO2 extraction to obtain Lippia thymoides Mart. & Schauer (Verbenaceae) essential oil rich in thymol and evaluation of its antimicrobial activity. The Journal of Supercritical Fluids, 168, Article 105064. https://doi.org/10.1016/j.supflu.2020.105064

• Sinha, S., Biswas, D., & Mukherjee, A. (2011). Antigenotoxic and antioxidant activities of palmarosa and citronella essential oils. Journal of Ethnopharmacology, 137(3), 1521-1527. https://doi.org/10.1016/j.jep.2011.08.046

• Snyder, J., Friedrich, J., & Christianson, D. (1984). Effect of moisture and particle size on the extractability of oils from seeds with supercritical CO2. Journal of the American Oil Chemists’ Society, 61(12), 1851-1856. https://doi.org/10.1007/BF02540816

• Sodeifian, G., Ardestani, N. S., Sajadian, S. A., & Moghadamian, K. (2018). Properties of Portulaca oleracea seed oil via supercritical fluid extraction: Experimental and optimization. The Journal of Supercritical Fluids, 135, 34-44. https://doi.org/10.1016/j.supflu.2017.12.026

• Sodeifian, G., Sajadian, S. A., & Honarvar, B. (2018). Mathematical modelling for extraction of oil from Dracocephalum kotschyi seeds in supercritical carbon dioxide. Natural Product Research, 32(7), 795-803. https://doi.org/10.1080/14786419.2017.1361954

• Sodeifian, G., Ardestani, N. S., Sajadian, S. A., & Ghorbandoost, S. (2016). Application of supercritical carbon dioxide to extract essential oil from Cleome coluteoides Boiss: experimental, response surface and grey wolf optimization methodology. The Journal of Supercritical Fluids, 114, 55-63. https://doi.org/10.1016/j.supflu.2016.04.006

• Sodeifian, G., Sajadian, S. A., & Ardestani, N. S. (2016). Optimization of essential oil extraction from Launaea acanthodes Boiss: Utilization of supercritical carbon dioxide and cosolvent. The Journal of Supercritical Fluids, 116, 46-56. https://doi.org/10.1016/j.supflu.2016.05.015

• Sodeifian, G., Sajadian, S. A., & Saadati Ardestani, N. (2017). Supercritical fluid extraction of omega-3 from Dracocephalum kotschyi seed oil: Process optimization and oil properties. The Journal of Supercritical Fluids, 119, 139-149. https://doi.org/10.1016/j.supflu.2016.08.019

• Sodeifian, G., & Usefi, M. M. B. (2023). Solubility, Extraction, and nanoparticles production in supercritical carbon dioxide: A mini‐review. ChemBioEng Reviews, 10(2), 133-166. https://doi.org/10.1002/cben.202200020

• Soh, S. H., Agarwal, S., Jain, A., Lee, L. Y., Chin, S. K., & Jayaraman, S. (2019). Mathematical modeling of mass transfer in supercritical fluid extraction of patchouli oil. Engineering Reports, 1(4), Article e12051. https://doi.org/10.1002/eng2.12051

• Sreenath, H. L., & Jagadishchandra, K. S. (2012). Cymbopogon spreng (Aromatic Grasses): In vitro culture, regeneration, and the production. In Y. P. S. Bajaj (Ed.), Biotechnolog in Agriculture and Forestry 15: Medicinal and Aromatic Plants III (pp. 211-234). Springer-Verlag.

• Timung, R., Barik, C. R., Purohit, S., & Goud, V. V. (2016). Composition and anti-bacterial activity analysis of citronella oil obtained by hydrodistillation: Process optimization study. Industrial Crops and Products, 94, 178-188. https://doi.org/10.1016/j.indcrop.2016.08.021

• Tyagi, B. K. (2016). Advances in vector mosquito control technologies, with particular reference to herbal products. In V. Veer & R. Gopalakrishnan (Eds.), Herbal Insecticides, Repellents and Biomedicines: Effectiveness and Commercialization (pp. 1-9). Springer. https://doi.org/10.1007/978-81-322-2704-5_1

• Uwineza, P. A., & Waśkiewicz, A. (2020). Recent advances in supercritical fluid extraction of natural bioactive compounds from natural plant materials. Molecules, 25(17), Article 3847. https://doi.org/10.3390/molecules25173847

• Wang, Q., Zhang, X., Cui, D., Bai, J., Wang, Z., Xu, F., & Wang, Z. (2023). Advances in supercritical water gasification of lignocellulosic biomass for hydrogen production. Journal of Analytical and Applied Pyrolysis, 170, Article 105934. https://doi.org/10.1016/j.jaap.2023.105934

• Wany, A., Jha, S., Nigam, V. K., & Pandey, D. M. (2013). Chemical analysis and therapeutic uses of citronella oil from Cymbopogon winterianus: A short review. International Journal of Advanced Research, 1(6), 504-521.

• Weng, D. C. J., Latip, J., Hasbullah, S. A., & Sastrohamidjojo, H. (2015). Optimal extraction and evaluation on the oil content of citronella oil extracted from Cymbopogon nardus. Malaysian Journal of Analytical Sciences, 19(1), 71-76.

• Wijesekera, R. O., Jayewardene, A. L., & Fonseka, B. D. (1973). Varietal differences in the constituents of citronella oil. Phytochemistry, 12(11), 2697-2704. https://doi.org/10.1016/0031-9422(73)85083-6

• Wu, H., Li, J., Jia, Y., Xiao, Z., Li, P., Xie, Y., Zhang, A., Liu, R., Ren, Z., Zhao, M., Zeng, C., & Li, C. (2019). Essential oil extracted from Cymbopogon citronella leaves by supercritical carbon dioxide: Antioxidant and antimicrobial activities. Journal of Analytical Methods in Chemistry, 2019, Article 8192439. https://doi.org/10.1155/2019/8192439

• Yousefi, M., Rahimi-Nasrabadi, M., Pourmortazavi, S. M., Wysokowski, M., Jesionowski, T., Ehrlich, H., & Mirsadeghi, S. (2019). Supercritical fluid extraction of essential oils. TrAC Trends in Analytical Chemistry, 118, 182-193. https://doi.org/10.1016/j.trac.2019.05.038

• Zhou, T., Wang, Y., Zheng, H., Du, B., & Zheng, L. (2022). Sustainable and eco-friendly strategies for polyester-cotton blends dyeing in supercritical CO2. Journal of CO2 Utilization, 55, Article 101816. https://doi.org/10.1016/j.jcou.2021.101816