Numerous attempts have been made to relate the free radical scavenging capacity of compounds to their antioxidant activity in foods even though antioxidant activity is dependent on both physical and ...chemical properties. The objective of this study was to compare the free radical scavenging activity of various compounds to their ability to inhibit lipid oxidation in foods. The order of free radical scavenging activity of polar compounds was ferulic acid > coumaric acid > propyl gallate > gallic acid > ascorbic acid as determined by a modified oxygen radical absorbance capacity, while the order of nonpolar compounds was rosmarinic acid > butylated hydroxytoluene ≥ tert-butylhydroquinone (TBHQ) > α-tocopherol as determined by the 2,2-diphenyl-1-picrylhydrazyl assay. Of these compounds, only propyl gallate and TBHQ were found to inhibit lipid oxidation in cooked ground beef as determiend by thiobarbituric acid reactive substances, while only propyl gallate, TBHQ, gallic acid, and rosmarinic acid inhibited lipid oxidation in an oil-in-water emulsion as determined by lipid hydroperoxides and headspace hexanal. These data indicate that the free radical scavenging assays tested have limited value in predicting the antioxidant activity in complex foods.
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This study examined partitioning of α-, β-, and γ-tocopherol and six polar antioxidants (Trolox, ferulic acid, caffeic acid, propyl gallate, gallic acid, and catechin) in mayonnaise. Partitioning of ...antioxidants between different phases was determined after separation of mayonnaise by either (a) centrifugation + ultracentrifugation or (b) centrifugation + dialysis. Antioxidants partitioned in accordance with their chemical structure and polarity: Tocopherols were concentrated in the oil phase (93−96%), while the proportion of polar antioxidants in the oil phase ranged from 0% (gallic acid and catechin) to 83% (Trolox). Accordingly, proportions of 6% (Trolox) to 80% (gallic acid and catechin) were found in the aqueous phase. Similar trends were observed after dialysis. After ultracentrifugation, large proportions of polar antioxidants were found in the “emulsion phase” and the “precipitate” (7−34% and 2−7%, respectively). This indicated entrapment of antioxidants at the oil−water interface in mayonnaise. The results signify that antioxidants partitioning into different phases of real food emulsions may vary widely. Keywords: Partitioning; emulsion; mayonnaise; tocopherol; polar antioxidants
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A new electroanalytical method has been developed for the determination of polar antioxidant compounds in extra virgin olive oils. This method is based on the extraction of polar antioxidant ...compounds from extra-virgin olive oils by means of a deep eutectic solvent and their determination by a modified screen-printed electrode platform. The platform sensitivity was increased by modifying the working electrode with MWCNT and TiO2 nanoparticles as modifiers and Nafion as a binder. The platform showed very good sensitivity in detecting polar antioxidant compounds in extra-virgin olive oils in a fairly wide range of concentrations. The measurements were performed by using square wave voltammetry. The extraction was performed without using organic solvents, making the method environmentally friendly. The proposed method has been compared with a common spectrophotometric one, the results appeared in good agreement. The method is sufficiently easy and quick to be used for screening analyses of polar antioxidant compounds in extra-virgin olive oils on the field.
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•Green DES employed to selectively extract polar antioxidants from olive oil•DES after extraction analyzed with nanomaterial modified screen-printed electrode•Extraction procedure possible without need for organic solvents•Platform able to quantify polar antioxidant compounds in olive oil samples•Discrimination possible between olive oil and oils from other seeds
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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