Shu‐Wen Huang

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInterfacial Phenomena in the Evaluation of Antioxidants: Bulk Oils vs EmulsionsEdwin N. Frankel, Shu-Wen Huang, Joseph Kanner, and J. Bruce GermanCite this: J. Agric. Food Chem. 1994, 42, 5, 1054–1059Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue 1 May 1994https://pubs.acs.org/doi/10.1021/jf00041a001https://doi.org/10.1021/jf00041a001research-articleACS PublicationsRequest reuse permissionsArticle Views2440Altmetric-Citations564LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

This study was aimed at evaluating the antioxidant activity of a commercial rosemary extract and the active constituents carnosol, carnosic acid, and rosmarinic acid, in inhibiting the formation and decomposition of hydroperoxides in tocopherol-stripped corn oil and in the corresponding corn oil-in-water emulsions. In bulk corn oil, the rosemary extract, carnosic acid, rosmarinic acid, and α-tocopherol were significantly more active than carnosol. In contrast, in corn oil-in-water emulsion, the rosemary compounds were less active than in bulk oil, and the rosemary extract, carnosic acid, carnosol, and α-tocopherol were more active than rosmarinic acid. Similar results were obtained in corn oil-in-water phosphate buffer emulsion at pH 5, but α-tocopherol was less active. Carnosol and carnosic acid were much more active antioxidants in corn oil-in-water emulsions buffered at pH 4 and 5 than at pH 7. The decreased antioxidant activity of the polar hydrophilic rosemary compounds in the emulsion system may be explained by their interfacial partitioning into the water, thus becoming less protective than in the bulk oil system. The effect of pH may be related to the stability of the rosemary antioxidants. Keywords: Antioxidants; rosemary extracts; corn oil; hydroperoxides; hexanal; bulk oil; emulsion

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAntioxidant activity of .alpha.- and .gamma.-tocopherols in bulk oils and in oil-in-water emulsionsShu-Wen Huang, Edwin N. Frankel, and J. Bruce GermanCite this: J. Agric. Food Chem. 1994, 42, 10, 2108–2114Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October 1994https://pubs.acs.org/doi/10.1021/jf00046a007https://doi.org/10.1021/jf00046a007research-articleACS PublicationsRequest reuse permissionsArticle Views1675Altmetric-Citations225LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Tea catechins showed different trends in relative antioxidant activity in different lipid systems. In corn oil triglycerides oxidized at 50 °C, epigallocatechin (EGC), epigallocatechin gallate (EGCG), and epicatechin gallate (ECG) were better antioxidants than epicatechin (EC) and catechin at 140 μM. Used as reference compounds, gallic acid (GA) was more active than propyl gallate (PG), and both were more effective than EC and catechin. However, in the corresponding corn oil-in-water emulsions, all tea catechins, GA, and PG were prooxidants at 5 and 20 μM by accelerating hydroperoxide and hexanal formation. In contrast, in soy lecithin liposomes oxidized at 50 °C, EGCG and PG were the best antioxidants, followed by EC, EGC, ECG, catechin, and GA at 20 μM. In liposomes oxidized at 37 °C with 10 μM cupric acetate, catechin and EC were better antioxidants than ECG, but EGCG, EGC, PG, and GA promoted lipid oxidation. The improved antioxidant activity observed for tea catechins in liposomes compared to emulsions can be explained by the greater affinity of the polar catechins toward the polar surface of the lecithin bilayers, thus affording better protection. The marked variation in activity among tea catechins may be partly explained by their different reducing potentials, stabilities, and relative partitions between phases in different lipid systems. Keywords: Antioxidants; prooxidants, tea catechins; catechin; epicatechin; epicatechin gallate; epigallocatechin; epigallocatechin gallate; gallic acid; propyl gallate; triglycerides; emulsion; liposome; antioxidant mechanism; interfacial oxidation; hydroperoxides; hexanal