{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T07:09:40Z","timestamp":1774595380781,"version":"3.50.1"},"reference-count":41,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2020,3,27]],"date-time":"2020-03-27T00:00:00Z","timestamp":1585267200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NORTE 2020 and FEDER","award":["NORTE-01-0145-FEDER-000006"],"award-info":[{"award-number":["NORTE-01-0145-FEDER-000006"]}]},{"name":"PIDDAC","award":["UIDB\/00690\/2020 - CIMO"],"award-info":[{"award-number":["UIDB\/00690\/2020 - CIMO"]}]},{"name":"PIDDAC","award":["UIDB\/50020\/2020 - LSRE-LCM"],"award-info":[{"award-number":["UIDB\/50020\/2020 - LSRE-LCM"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Replacing synthetic surfactants by natural alternatives when formulating nanoemulsions has gained attention as a sustainable approach. In this context, nanoemulsions based on sweet almond oil and stabilized by saponin from Quillaja bark with glycerol as cosurfactant were prepared by the high-pressure homogenization method. The effects of oil\/water (O\/W) ratio, total surfactant amount, and saponin\/glycerol ratio on their stability were analyzed. The formation and stabilization of the oil-in-water nanoemulsions were analyzed through the evaluation of stability over time, pH, zeta potential, and particle size distribution analysis. Moreover, a design of experiments was performed to assess the most suitable composition based on particle size and stability parameters. The prepared nanoemulsions are, in general, highly stable over time, showing zeta potential values lower than \u221240 mV, a slight acid behavior due to the character of the components, and particle size (in volume) in the range of 1.1 to 4.3 \u00b5m. Response surface methodology revealed that formulations using an O\/W ratio of 10\/90 and 1.5 wt% surfactant resulted in lower particle sizes and zeta potential, presenting higher stability. The use of glycerol did not positively affect the formulations, which reinforces the suitability of preparing highly stable nanoemulsions based on natural surfactants such as saponins.<\/jats:p>","DOI":"10.3390\/molecules25071538","type":"journal-article","created":{"date-parts":[[2020,4,3]],"date-time":"2020-04-03T05:55:16Z","timestamp":1585893316000},"page":"1538","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":66,"title":["Formulation and Optimization of Nanoemulsions Using the Natural Surfactant Saponin from Quillaja Bark"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8436-9216","authenticated-orcid":false,"given":"Tatiana B.","family":"Schreiner","sequence":"first","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o de Montanha (CIMO), Instituto Polit\u00e9cnico de Bragan\u00e7a, Campus de Santa Apol\u00f3nia, 5300-253 Bragan\u00e7a, Portugal"},{"name":"Laboratory of Separation and Reaction Engineering \u2013 Laboratory of Catalysis and Materials (LSRE-LCM) Department of Chemical Engineering, Faculty of Engineering University of Porto, Rua Dr. Roberto Frias, S\/N, 4200-465 Porto, Portugal"}]},{"given":"Arantzazu","family":"Santamaria-Echart","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o de Montanha (CIMO), Instituto Polit\u00e9cnico de Bragan\u00e7a, Campus de Santa Apol\u00f3nia, 5300-253 Bragan\u00e7a, Portugal"}]},{"given":"Andreia","family":"Ribeiro","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o de Montanha (CIMO), Instituto Polit\u00e9cnico de Bragan\u00e7a, Campus de Santa Apol\u00f3nia, 5300-253 Bragan\u00e7a, Portugal"},{"name":"Laboratory of Separation and Reaction Engineering \u2013 Laboratory of Catalysis and Materials (LSRE-LCM) Department of Chemical Engineering, Faculty of Engineering University of Porto, Rua Dr. Roberto Frias, S\/N, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6595-9165","authenticated-orcid":false,"given":"Ant\u00f3nio M.","family":"Peres","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o de Montanha (CIMO), Instituto Polit\u00e9cnico de Bragan\u00e7a, Campus de Santa Apol\u00f3nia, 5300-253 Bragan\u00e7a, Portugal"}]},{"given":"Madalena M.","family":"Dias","sequence":"additional","affiliation":[{"name":"Laboratory of Separation and Reaction Engineering \u2013 Laboratory of Catalysis and Materials (LSRE-LCM) Department of Chemical Engineering, Faculty of Engineering University of Porto, Rua Dr. Roberto Frias, S\/N, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9211-857X","authenticated-orcid":false,"given":"Sim\u00e3o P.","family":"Pinho","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o de Montanha (CIMO), Instituto Polit\u00e9cnico de Bragan\u00e7a, Campus de Santa Apol\u00f3nia, 5300-253 Bragan\u00e7a, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6844-333X","authenticated-orcid":false,"given":"Maria Filomena","family":"Barreiro","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o de Montanha (CIMO), Instituto Polit\u00e9cnico de Bragan\u00e7a, Campus de Santa Apol\u00f3nia, 5300-253 Bragan\u00e7a, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2020,3,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/j.jcis.2018.01.105","article-title":"Concentration effect of Quillaja saponin\u2014Co-surfactant mixtures on emulsifying properties","volume":"519","author":"Reichert","year":"2018","journal-title":"J. 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