{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,9]],"date-time":"2026-04-09T01:26:00Z","timestamp":1775697960174,"version":"3.50.1"},"reference-count":44,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2022,11,21]],"date-time":"2022-11-21T00:00:00Z","timestamp":1668988800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Foundation for Science and Technology (FCT)","award":["LA\/P\/0045\/2020"],"award-info":[{"award-number":["LA\/P\/0045\/2020"]}]},{"name":"Foundation for Science and Technology (FCT)","award":["UIDB\/00511\/2020"],"award-info":[{"award-number":["UIDB\/00511\/2020"]}]},{"name":"Foundation for Science and Technology (FCT)","award":["UIDP\/00511\/2020"],"award-info":[{"award-number":["UIDP\/00511\/2020"]}]},{"name":"Foundation for Science and Technology (FCT)","award":["PD\/BD\/114312\/2016"],"award-info":[{"award-number":["PD\/BD\/114312\/2016"]}]},{"name":"oundation for Science and Technology for funding Emanuel Costa\u00b4s","award":["LA\/P\/0045\/2020"],"award-info":[{"award-number":["LA\/P\/0045\/2020"]}]},{"name":"oundation for Science and Technology for funding Emanuel Costa\u00b4s","award":["UIDB\/00511\/2020"],"award-info":[{"award-number":["UIDB\/00511\/2020"]}]},{"name":"oundation for Science and Technology for funding Emanuel Costa\u00b4s","award":["UIDP\/00511\/2020"],"award-info":[{"award-number":["UIDP\/00511\/2020"]}]},{"name":"oundation for Science and Technology for funding Emanuel Costa\u00b4s","award":["PD\/BD\/114312\/2016"],"award-info":[{"award-number":["PD\/BD\/114312\/2016"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Processes"],"abstract":"<jats:p>Rice is one of the most consumed cereals in the world. From rice processing, rice bran is obtained, and only a part of this by-product is effectively used. Rice bran oil can be obtained and used as an alternative feedstock for biodiesel production, although few studies exist to support its exploitation. In addition, pretreatment is required to reduce its acidity and allow for its integration in the conventional industrial process. This work evaluated two pretreatment processes aiming to reduce the free fatty acids (FFAs) content of rice bran oil by employing an acid-catalyzed process and a biocatalyzed process. The results allowed us to assess the efficiency and effectiveness of both pretreatments. For that purpose, acid (45, 55 and 65 \u00b0C, using H2SO4 concentrations of 2 wt.% or 4 wt.% and a methanol:oil molar ratio of 9:1) and enzymatic FFAs conversion (35 \u00b0C using a 6:1 methanol:oil molar ratio and 5 wt.% of Thermomyces lanuginosus) were evaluated using rice bran oil with an acid value around 47 mg KOH.g\u22121, and the reaction kinetics were assessed. Acid esterification enabled a 92% acidity reduction (65 \u00b0C, 4 wt.% of catalyst) after 8 h, with the final product presenting an acid value of 3.7 mg KOH.g\u22121 and a biodiesel purity of 42 wt.%. The enzymatic process allowed an acidity reduction of 82%, resulting in a product with an acid value of 7.0 mg KOH.g\u22121; however, after 24 h, the biodiesel purity was 87 wt.% (almost a two-fold increase compared to that obtained in the homogeneous process), revealing the conversion of both free fatty acids and glycerides. The study of the reaction kinetics of the homogeneous (acid) esterification showed that, for temperatures &gt; 45 \u00b0C, the constant rate increased with temperature. A higher constant rate was obtained for the temperature of 55 \u00b0C using 4 wt.% of catalyst (k\u2032 = 0.13 min\u22121). For the heterogeneous (enzymatic) esterification, the constant rate obtained was lower (k\u2032 = 0.028 min\u22121), as expected. The study revealed the technical viability of the esterification pretreatment of rice bran oil and the important parameters concerning the performance of the pretreatment solutions. Finally, the enzymatic process should be further explored, aiming to develop more ecofriendly processes (water and energy savings) to produce biodiesel from oils with a high acidity (low-cost raw materials).<\/jats:p>","DOI":"10.3390\/pr10112460","type":"journal-article","created":{"date-parts":[[2022,11,21]],"date-time":"2022-11-21T03:09:30Z","timestamp":1669000170000},"page":"2460","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Exploiting the Complementary Potential of Rice Bran Oil as a Low-Cost Raw Material for Bioenergy Production"],"prefix":"10.3390","volume":"10","author":[{"given":"Emanuel","family":"Costa","sequence":"first","affiliation":[{"name":"Department of Metallurgical and Materials Engineering, LEPABE, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"},{"name":"ALiCE-Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9326-7043","authenticated-orcid":false,"given":"Manuel Fonseca","family":"Almeida","sequence":"additional","affiliation":[{"name":"Department of Metallurgical and Materials Engineering, LEPABE, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"},{"name":"ALiCE-Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}]},{"given":"Maria Concei\u00e7\u00e3o","family":"Alvim-Ferraz","sequence":"additional","affiliation":[{"name":"ALiCE-Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"Department of Chemical Engineering, LEPABE, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0966-0537","authenticated-orcid":false,"given":"Joana Maia","family":"Dias","sequence":"additional","affiliation":[{"name":"Department of Metallurgical and Materials Engineering, LEPABE, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"},{"name":"ALiCE-Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.jiec.2020.08.024","article-title":"A review on influence of reactor technologies and kinetic studies for biodiesel application","volume":"91","author":"Raheem","year":"2020","journal-title":"J. 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