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Synthetic Antioxidants (synthetic + antioxidant)
Selected AbstractsKinetic Study of the Quenching Reaction of Singlet Oxygen by Common Synthetic Antioxidants (tert -Butylhydroxyanisol, tert -di-Butylhydroxytoluene, and tert -Butylhydroquinone) as Compared with ,-TocopherolJOURNAL OF FOOD SCIENCE, Issue 5 2009Ji In Kim ABSTRACT:, Effects of synthetic phenolic antioxidants (BHA, BHT, and TBHQ) on the methylene blue (MB) sensitized photooxidation of linoleic acid as compared with that of ,-tocopherol have been studied. Their antioxidative mechanism was studied by both ESR spectroscopy in a 2,2,6,6-tetramethylpiperidone (TMPD)-methylene blue (MB) system and spectroscopic analysis of rubrene oxidation induced by a chemical source of singlet oxygen. Total singlet oxygen quenching rate constants (kox,Q+kq) were determined using a steady state kinetic equation. TBHQ showed the strongest protective activity against the MB sensitized photooxidation of linoleic acid, followed by BHA and BHT. TBHQ (1 × 10,3 M) exhibited 86.5% and 71.4% inhibition of peroxide and conjugated diene formations, respectively, in linoleic acid photooxidation after 60-min light illumination. The protective activity of TBHQ against the photosensitized oxidation of linoleic acid was almost comparable to that of ,-tocopherol. The data obtained from ESR and rubrene oxidation studies clearly showed the strong singlet oxygen quenching ability of TBHQ. The kox,Q+kq of BHA, BHT, and TBHQ were determined to be 3.37 × 107, 4.26 × 106, and 1.67 × 108 M,1 s,1, respectively. The kox,Q+kq of TBHQ was within the same order of magnitude of that of ,-tocopherol, a known efficient singlet oxygen quencher. There was a high negative correlation (r2,=,,0.991) between log (kox,Q+kq) and reported oxidation potentials for the synthetic antioxidants, indicating their charge-transfer mechanism for singlet oxygen quenching. This is the 1st report on the kinetic study on kox,Q+kq of TBHQ in methanol as compared with other commonly used commercial synthetic antioxidants and ,-tocopherol. [source] 3246: Synthetic antioxidants for prevention of cataractACTA OPHTHALMOLOGICA, Issue 2010P KADOR [source] Antioxidant Activity of Degradable Polymer Poly(trolox ester) to Suppress Oxidative Stress Injury in the CellsADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Paritosh P. Wattamwar Abstract Oxidative stress is a pathological condition that has been implicated as a central player in a variety of diseases, including vascular and neurodegenerative diseases. More recently, oxidative stress has also been shown to be involved in the biological incompatibility of many materials, especially at the nanoscale. As such, there is a critical need for new biomaterials that can inhibit this response, improving the compatibility of medical devices. In this work, trolox, a synthetic antioxidant and water-soluble analogue of Vitamin E, is polymerized to form an oxidation active polymer as a new class of biomaterial. Synthesized poly(trolox ester) polymers were formulated into nanoparticles using a single emulsion technique, and their size was controlled by changing the polymer concentration in the organic solvent. Nanoparticle cytotoxicity, protective effects against cellular oxidative stress, and degradation kinetics were all evaluated. Poly(trolox ester) nanoparticles were found to have little to no cytotoxicity and were capable of suppressing cellular oxidative stress induced by cobalt nanoparticles. In vitro degradation studies of poly(trolox ester) nanoparticles indicate that the antioxidant activity of nanoparticles was derived from its enzymatic degradation to release active antioxidants. [source] ANTIOXIDANT ACTIVITY AND TOTAL PHENOLIC CONTENTS IN PEEL AND PULP OF CHINESE JUJUBE (ZIZIPHUS JUJUBA MILL) FRUITSJOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2009ZIPING XUE ABSTRACT Total phenolic contents in peel and pulp of the fruits of three Chinese jujube cultivars (Ziziphus jujuba cv. mayazao, Z. jujuba cv. dongzao and Z. jujuba cv. yuanzao) were determined. The antioxidant activities in peel and pulp of the jujube fruits were measured by different methods, including 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC). The total phenolic content in peel was five to six times higher than that in the pulp of all the three cultivars. The phenolics contents in the jujube were different with cultivars. The EC50 (Concentration of lyophilized samples needed to decrease the initial DPPH radical concentration by 50%), FRAP and TEAC values of the peel and pulp were remarkably correlated to their total phenolic contents (R = ,0.922, R = 0.985 and R = 0.997, respectively). The results indicated that the high capacity of antioxidant of Chinese jujube fruit could be attributed to the high phenolic contents in the fruit. PRACTICAL APPLICATIONS There was an expanding quest surrounding the use of antioxidant because they have the capacity to protect from the damage because of free radicals and reactive oxygen species. However, the safety of synthetic antioxidant was challenged. Much attention has been focused on the use of natural antioxidant. Interest in food phenolics had increased greatly because of their antioxidant and possible promoting-health role in human health. In this study, total phenolic contents and antioxidant capacities in vitro of Chinese jujube (Ziziphus jujuba Mill) peel and pulp were researched. The work would help to explore a natural antioxidant for possible application in food and dietary supplemental products for health promotion. [source] Oxidative stability of palm- and soybean-based medium- and long-chain triacylglycerol (MLCT) oil blendsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2009Soo Peng Koh Abstract BACKGROUND: Medium- and long-chain triacylglyerols (MLCT) enzymatically esterified using Lipozyme RM IM lipase has very low oxidative stability as it does not contain any antioxidants. The aim of this work was to study the ability of various antioxidants to increase the oxidative stability of palm- and soybean-based MLCT blends which assist to bring up the oxidative stability of both MLCT blends. In this study, the effectiveness of rosemary extracts, sage extracts, tert -butylhydroquinone (TBHQ) and mixtures of tert -butyl-4-hydroxyanisole (BHA) and tert -butyl- p -hydroxytoluene (BHT) in protecting against oxidation of various MLCT blends was investigated. RESULTS: Blending of MLCT oil with either palm olein or soybean oil improved its smoke point values and oxidative stability. TBHQ addition to both palm- and soybean-based MLCT blends increased oxidative stability. Combination of BHA and BHT showed no significant improvement (P > 0.05) in ability to protect blends from oxidation compared to natural antioxidants such as sage or rosemary extracts. CONCLUSION: Blended oils with 500 g kg,1 MLCT and 500 g kg,1 palm olein (MP5) were the most suitable for use at high temperature based on the fatty acid composition of the MLCT blends, which subsequently had an effect on thermal oxidative stability. In general, addition of either natural or synthetic antioxidant assisted in improving the antioxidative strength of both MLCT blends. MLCT blends with added TBHQ showed the highest thermal oxidative stability among the antioxidants used. Copyright © 2008 Society of Chemical Industry [source] Characterization of hydroxyaromatic compounds in vegetable oils by capillary electrophoresis with direct injection in an oil-miscible KOH/propanol/methanol mediumELECTROPHORESIS, Issue 17 2005Carla R. B. Mendonça Abstract The separation of hydroxyaromatic compounds in vegetable oils, including synthetic antioxidants (3- tert -butyl-4-hydroxyanisol and 2,6-di- tert -butyl-4-hydroxytoluene), E-vitamers and other natural oil components, by nonaqueous capillary electrophoresis in an oil-miscible background electrolyte (BGE) was investigated. The BGE contained 40,mM KOH in a methanol/1-propanol (PrOH) mixture (15:85 v/v). The oil samples were 1:1 diluted with PrOH and directly injected in the capillary. Under negative polarity (cathode at the injection end), the anionic solutes moved faster than the electroosmotic flow, being well-resolved among them and from the triacylglycerols. Using virgin palm, extra virgin olive, wheat germ, virgin soybean and other oils, the capability of the procedure to quickly yield a characteristic profile of the biophenols present in the sample was demonstrated. The , -, (,,+,,)- (as unresolved pair) and , -tocopherols of a soybean oil sample were quantified. [source] Stabilization of phytosterols in rapeseed oil by natural antioxidants during heatingEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 11 2009Dominik Kmiecik Abstract Antioxidants are substances that can reduce negative changes in fat. Many antioxidants are very effective during storage, but during heating they lose their properties. It is very important to find antioxidants that will be stable at high temperatures and protect fat throughout the entire frying process. The aim of this study was to estimate the effect of natural and synthetic antioxidants on changes in phytosterols of rapeseed oil during heating. Oil with antioxidants was heated at 180,°C for 4,h in a Rancimat® and in an Oxidograph®. Ethanol extract of rosemary, ethanol extract of green tea, and BHT were used in the study. The contents of phytosterols (sitosterol, campesterol, avenasterol, brassicasterol, stigmasterol) and oxyphytosterols (7,- and 7,-hydroxysterol, 5,,6,- and 5,,6,-epoxysterol, 7-ketosterol and triols) were estimated by gas chromatography. In all samples with antioxidants, a lower decrease of phytosterols and a lower increase of total oxyphytosterols were observed in comparison with the control sample (without antioxidant). The antioxidant effect depends on the type of the antioxidant and the heating conditions. The best results were observed in samples with natural antioxidants. BHT was a substance that protected phytosterols as well, but not as effectively as the other antioxidants. [source] Are natural antioxidants better , and safer , than synthetic antioxidants?EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 8 2007Jan Pokorný No abstracts. [source] Potential uses and applications of treated wine waste: a reviewINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2006Ioannis S. Arvanitoyannis Summary Recently, there has been an upsurge in the exploitation of the waste materials generated by the wine industry. Wine waste is characterised by the presence of natural antioxidants much safer than synthetic antioxidants. Wine waste-derived antioxidants have been recently used in the food industry. Moreover, wine waste can be potentially used as soil conditioner, as adsorbent for heavy metals, for fertiliser and for pullulan production. This review aims at presenting the most important and economically viable applications of treated wine waste. [source] EFFECT OF DIRECT APPLICATIONS OF SAGE (SALVIA OFFICINALIS L.) LEAVES ON OXIDATIVE STABILITY OF SUNFLOWER OIL DURING ACCELERATED STORAGEJOURNAL OF FOOD QUALITY, Issue 5 2009EDA ÇALIKO ABSTRACT In this study, various sage applications were examined on oxidative stability of sunflower oil during accelerated storage. There are three applications: (1) direct sage leaves (S); (2) deodorized sage leaves (DeS); and (3) essential oil of sage leaves. The main compounds of essential oil were identified as, -thujone (35.87%),, -thujone (14.41%), 1,8-cineol (10.59%) and camphor (10.09%). Oxidative stability of these three applications was tested by Schall Oven test at 60C applying peroxide value and conjugated dienes, and Rancimat at 110C. Whereas the highest antioxidants activity was found for 2% S followed by 0.5% S and 2% DeS, all sage treatments statistically retarded the oxidation compared with the control sample. The most appealing result was that the residue can be used as a natural antioxidants. That means the reuse of residue may decrease economic losses and health risk in comparison with synthetic antioxidants and extracts because it is completely natural and contains no residual solvent. PRACTICAL APPLICATIONS While almost all of previous studies were concentrated on the use of herb extracts, our study investigates the results of direct application of sage on oxidation. Especially with this study, we have evaluated a possible application area for sage residue leftover after the deodorization process. [source] EFFECTS OF PRETREATMENT WITH ROSEMARY (ROSMARINUS OFFICINALIS L.) IN THE PREVENTION OF LIPID OXIDATION IN SALTED TILAPIA FILLETSJOURNAL OF FOOD QUALITY, Issue 5 2008M. DA SILVA AFONSO ABSTRACT To delay lipid oxidation during meat processing, synthetic antioxidants have been used in the food industry, but the consumers' concern over their toxicity increased interest in research with natural antioxidants. The aim of this work was to analyze the water activity (Aw), thiobarbituric acid reactive substances (TBARS), moisture and trichloroacetic acid-soluble nitrogen (TCASN) in brined tilapia fillets treated or pretreated with natural rosemary extract (Rosmarinus officinalis) and stored for 240 days at ,18C. Higher Aw (0.900 ± 0.010) and moisture (70.13 ± 0.20) values were observed in the pretreated fillets. The TBARS values in the treatment (3.31 ± 0.79) and pretreatment (3.39 ± 0.53) were half the value of the control treatment (6.14 ± 1.21) at 240 days. Statistical differences were observed in TCASN values in 180 (0.112 ± 0.020) and 240 (0.132 ± 0.017) days, with the pretreatment showing a more protective effect in protein oxidation. In this study, rosemary proved to be protective during the frozen storage, especially when its extract was used as pretreatment, before the salting process. PRACTICAL APPLICATIONS Fish consumption is highly elastic, because the annual average consumption of seafood per person in Brazil is only 6.8 kg. The federal government has set a goal to increase it to 12 kg by 2007. Salting is an older food preservation process still used today, and is extremely important because, despite advances in food technology, increased monitoring and improved knowledge, it is emphasized as an easy, cheap and effective process that does not require refrigeration. Tilapia is a highly prolific fish, with a production volume that is increasingly higher each year in Brazil. Therefore, it calls for interesting research to allow an increased shelf life for this species. [source] Kinetic Study of the Quenching Reaction of Singlet Oxygen by Common Synthetic Antioxidants (tert -Butylhydroxyanisol, tert -di-Butylhydroxytoluene, and tert -Butylhydroquinone) as Compared with ,-TocopherolJOURNAL OF FOOD SCIENCE, Issue 5 2009Ji In Kim ABSTRACT:, Effects of synthetic phenolic antioxidants (BHA, BHT, and TBHQ) on the methylene blue (MB) sensitized photooxidation of linoleic acid as compared with that of ,-tocopherol have been studied. Their antioxidative mechanism was studied by both ESR spectroscopy in a 2,2,6,6-tetramethylpiperidone (TMPD)-methylene blue (MB) system and spectroscopic analysis of rubrene oxidation induced by a chemical source of singlet oxygen. Total singlet oxygen quenching rate constants (kox,Q+kq) were determined using a steady state kinetic equation. TBHQ showed the strongest protective activity against the MB sensitized photooxidation of linoleic acid, followed by BHA and BHT. TBHQ (1 × 10,3 M) exhibited 86.5% and 71.4% inhibition of peroxide and conjugated diene formations, respectively, in linoleic acid photooxidation after 60-min light illumination. The protective activity of TBHQ against the photosensitized oxidation of linoleic acid was almost comparable to that of ,-tocopherol. The data obtained from ESR and rubrene oxidation studies clearly showed the strong singlet oxygen quenching ability of TBHQ. The kox,Q+kq of BHA, BHT, and TBHQ were determined to be 3.37 × 107, 4.26 × 106, and 1.67 × 108 M,1 s,1, respectively. The kox,Q+kq of TBHQ was within the same order of magnitude of that of ,-tocopherol, a known efficient singlet oxygen quencher. There was a high negative correlation (r2,=,,0.991) between log (kox,Q+kq) and reported oxidation potentials for the synthetic antioxidants, indicating their charge-transfer mechanism for singlet oxygen quenching. This is the 1st report on the kinetic study on kox,Q+kq of TBHQ in methanol as compared with other commonly used commercial synthetic antioxidants and ,-tocopherol. [source] Antioxidant Activity of Crude Extract, Alkaloid Fraction, and Flavonoid Fraction from Boldo (Peumus boldus Molina) LeavesJOURNAL OF FOOD SCIENCE, Issue 5 2004N. Quezada ABSTRACT: Boldo is an endemic plant from Chile widely used in folk medicine, whose biological (mainly antioxidant) activity has been attributed to the presence of the alkaloid boldine. The aim of this study was to determine the contribution of the flavonoid and other crude fractions from boldo leaves to the antioxidant activity of extracts. The main constituent in the flavonoid fraction was also isolated. The antioxidant activity and reducing power of crude boldo extract and fractions were measured and compared with natural and synthetic antioxidants. The antioxidant activity of boldo leaf extracts came mainly from the flavonoid fraction (44.1%) followed by the alkaloid fraction (15.6%), with catechin and boldine being the main contributors of the antioxidant activity of these 2 fractions (60.9% and 35.6% of the total activity, respectively). On the basis of these results, we propose to use catechin and boldine as markers for the antioxidant activity of boldo leaves. Tailor-made antioxidants to be used in foods can be prepared by enriching these 2 fractions. [source] Antioxidant activity of ginger extract in sunflower oilJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2003Zia-ur-Rehman Abstract The antioxidant activity of dichloromethane extract from ginger was evaluated during 6 months of storage of refined sunflower oil at 25 and 45,°C. Free fatty acid (FFA) content, peroxide value (POV) and iodine value (IV) were used as criteria to assess ginger extract as an antioxidant. After 6 months of storage at 45,°C, sunflower oil containing 1600 and 2400,ppm ginger extract showed lower FFA contents (0.083 and 0.080%) and POVs (24.5 and 24.0,meq,kg,1) than the control sample (FFA contents 0.380%, POV 198.0,meq,kg,1). Sunflower oil containing 200,ppm butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) showed FFA contents of 0.089 and 0.072% and POVs of 26.5 and 24.7,meq,kg,1 respectively after 6 months of storage at 45,°C. Similarly, after 6 months of storage at 45,°C, IVs of sunflower oil containing 1600 and 2400,ppm ginger extract were 80 and 92 respectively, higher than that of the control sample (53). However, IVs of sunflower oil treated with 200,ppm BHA and BHT were 94 and 96 respectively after 6 months of storage at 45,°C. These results illustrate that ginger extract at various concentrations exhibited very strong antioxidant activity, almost equal to that of synthetic antioxidants (BHA and BHT). Ginger extract also showed good thermal stability and exhibited 85.2% inhibition of peroxidation of linoleic acid when heated at 185,°C for 120,min. Therefore the use of ginger extract in foods is recommended as a natural antioxidant to suppress lipid oxidation. © 2003 Society of Chemical Industry [source] | |||||||||||||