Beta-carotene Bleaching Assay Research Articles

Antioxidant Assays for Plant and Food Components

Recently, research on natural antioxidants has become increasingly active in various fields. Accordingly, numerous articles on natural antioxidants, including polyphenols, flavonoids, vitamins, and volatile chemicals, have been published. Assays developed to evaluate the antioxidant activity of plants and food constituents vary. Therefore, to investigate the antioxidant activity of chemical(s), choosing an adequate assay based on the chemical(s) of interest is critical. There are two general types of assays widely used for different antioxidant studies. One is an assay associated with lipid peroxidations, including the thiobarbituric acid assay (TBA), malonaldehyde/high-performance liquid chromatography (MA/HPLC) assay, malonaldehyde/gas chromatography (MA/GC) assay, beta-carotene bleaching assay, and conjugated diene assay. Other assays are associated with electron or radical scavenging, including the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay, ferric reducing/antioxidant power (FRAP) assay, ferrous oxidation-xylenol orange (FOX) assay, ferric thiocyanate (FTC) assay, and aldehyde/carboxylic acid (ACA) assay. In this review, assays used recently were selected for extended discussion, including discussion of the mechanisms underlying each assay and its application to various plants and foods.

Supercritical carbon dioxide fluid extraction of Hibiscus cannabinus L. seed oil: A potential solvent-free and high antioxidative edible oil

The supercritical fluid extraction (SFE) trends and antioxidant activities of Hibiscus cannabinus seed oils were studied. SFE results indicate that extraction pressure is the major factor determining the oil yield. In comparison, classic Soxhlet extraction (SOX/L) yielded higher oil content than SFE ( P < 0.05). However, no significant differences in oil content were observed in SFE at 600 bars/80 °C, rapid Soxhlet extraction (SOX/S) and conventional ultra-sonic assisted solvent extraction (SONIC) ( P > 0.05). Antioxidant activities of H. c annabinus seed oils were compared with 7 types of commercial edible oils. DPPH scavenging activity test indicated that H. cannabinus seed oil extracted by SFE at 200 bars/80 °C possessed the highest antiradical activity whereas beta-carotene bleaching (BCB) assay revealed that all H. cannabinus seed oils (except for SFE at 400 bars/80 °C and 600 bars/80 °C) exhibited higher antioxidant activity than all commercial edible oils ( P < 0.05). Thus, SFE – H. cannabinus seed oil may serve as an excellent source of solvent-free edible oil with high antioxidant properties.

Antioxidant activity of three edible seaweeds from two areas in South East Asia

Total phenolic content (TPC) and antioxidant activity (AOA) of 50% aqueous methanol extracts of the marine algae, Padina antillarum, Caulerpa racemosa and Kappaphycus alvarezzi were studied. TPC was measured using Folin–Ciocalteu method while 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), ferrous ion chelating (FIC) assay and beta carotene bleaching (BCB) assay were used to study their AOA. P. antillarum was found to have the highest TPC, 2430±208 mg gallic acid equivalents (GAE) per 100 g dried sample and ascorbic acid equivalent antioxidant capacity (AEAC), 1140±85 mg AA/100 g. C. racemosa and K. alvarezzi displayed lower TPC and AEAC. C. racemosa had 144±22 mg GAE/100 g dried sample of TPC and 14.3±2.0 mg AA/100 g of AEAC, while K. alvarezzi had 115±35 mg/100 g dried sample of TPC and 37.8±16.8 mg AA/100 g of AEAC. In addition, P. antillarum displayed the highest reducing power, 15.7±2.6 mg GAE/g and highest chelating ability. C. racemosa and K. alvarezzi exhibited lower reducing power, 0.737±0.423 mg GAE/g and 0.561±0.269 mg GAE/g, and lower chelating ability. However, the AOA of these three seaweeds as assessed by BCB assay were equally high.

Antioxidant activities of various extracts of lotus (Nelumbo nuficera Gaertn) rhizome.

Lotus rhizome powder was extracted with solvents of different polarities. Antioxidant activities of the extracts were evaluated by a 2, 2'-diphenylpicrylhydrazyl (DPPH) assay and a beta-carotene bleaching assay, and compared with that of butylated hydroxyanisole (BHA) and ascorbic acid. Methanol showed the highest extract yield among all of solvents. Although acetone extract had the highest total phenolics content, methanol extract had the highest total phenolics recovery from lotus powder (20.1 mg catechin equivalents/100g lotus powder). Extract of either methanol or acetone demonstrated the highest DPPH scavenging activity at both 66.7 mg/L and 133.3 mg/L. All extracts exhibited higher antioxidant activity coefficient (AAC) than that of ascorbic acid, furthermore, dichloromethane and petroleum extracts had comparable AAC with BHA by the beta-carotene bleaching assay. The properties of the extracting solvents significantly affected the yield, total phenolics content and antioxidant activity of lotus rhizome extracts.

Antioxidant activity, anthocyanins, and phenolics of rabbiteye blueberry ( Vaccinium ashei) fluid products as affected by fermentation

Frozen rabbiteye blueberries ( Vaccinium ashei) were processed into juice (BJ), wines made without (BW1) or with (BW2) skin contact fermentation, and vinegars made from BW1 (JV), BW2 (WV) or blueberries (BV). Total phenolics, total anthocyanins, antioxidant activities (beta-carotene bleaching assay and ferric thiocyanate assay), and antiradical activity (DPPH radical-scavenging method) of these fluid products were determined. The differences in total anthocyanin contents of all blueberry products were significant. The BW2 had the highest content of anthocyanins and polyphenols and the highest beta-carotene bleaching activity and antiradical activity. Acetification decreased total anthocyanin content, total polyphenols and antioxidant activities. Correlations indicate that anthocyanins made significant contributions than did phenolics to antioxidant activities of products. The abilities of BJ, BW1 (wine from blueberry juice), and BW2 to inhibit linoleic acid peroxidation were high (∼95%). The abilities of vinegar products to inhibit linoleic acid peroxidation were low. The results indicate that skin-contact fermentation is a better method for obtaining higher antioxidant activity of blueberry products. Also, acetification significantly decreased anthocyanins and antioxidant activities.

Antioxidant Activity of Supramolecular Water-Soluble Fullerenes Evaluated by β-Carotene Bleaching Assay

We investigated the antioxidant activity of supramolecular water-soluble fullerenes, polyvinylpyrrolidone (PVP)-entrapped C(60), and gamma-cyclodextrin (CD)-bi-capped C(60), based on comparable beta-carotene bleaching assay. Antioxidant activity against reactive oxygen species (ROS) generated by three different methods, (i) autoxidation of linoleic acid, (ii) hydrogen peroxide promoter, and (iii) photoirradiation, was evaluated as percent of inhibition relative to a control experiment in view of the bleaching rate constant (k(obs)) as well as the persistent absorbency of beta-carotene. Water-soluble fullerenes exhibit significant inhibitory effects on the oxidative discoloration of beta-carotene in any system.

Composition of the Volatile Fraction of Ocotea bofo Kunth (Lauraceae) Calyces by GC-MS and NMR Fingerprinting and Its Antimicrobial and Antioxidant Activity

The chemical composition of the essential oil obtained by steam distillation of the floral calyces of Ocotea bofo Kunth (Lauraceae) was studied by means of GC, GC-MS, and 1H, 13C, and bidimensional NMR (COSY, HSQC, HMBC). Twenty-five constituents were identified, and estragole (48.7%), alpha-phellandrene (19.6%) and sabinene (10.4%) were found to be the major components. Antimicrobial activity against six aerobic bacteria and five yeasts and antioxidant activity performed by photochemiluminescence (PCL), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and beta-carotene bleaching assays are reported. The oil showed fair inhibiting properties against bacteria and a good inhibition against most yeasts. Its radical scavenging and chain-breaking antioxidant properties were comparable to or better than those provided by synthetic controls. Particular emphasis has been given to the use of NMR as a fast and reliable tool to discriminate O. bofo essential oil from other commercial anethole- and estragole-rich oils, namely, Illicium verum, Foeniculum vulgare, and Artemisia dracunculus.

Antioxidant Activity of Commercial Soft and Hard Wheat (Triticum aestivumL.) as Affected by Gastric pH Conditions

Phenolic compounds from soft and hard wheat and their milling fractions were extracted into distilled deionized water, and their in vitro antioxidant activities were evaluated. Wheat samples were used as such (nontreated) or subjected to pH adjustment (treated) in order to simulate gastrointestinal pH conditions. The total phenolic content (TPC) was determined using Folin-Ciocalteu's procedure. The total antioxidant activity (TAA) was determined using Trolox equivalent antioxidant capacity assay and expressed as Trolox equivalents. The antioxidant activity of wheat extracts was also evaluated using the beta-carotene bleaching assay, scavenging of 2,2-diphenyl-1-picrylhydrazyl radical, and inhibition of oxidation of human low density lipoprotein cholesterol. The TPC, TAA, and antioxidant potential, evaluated using different methods of wheat samples, were significantly increased following gastrointestinal tract-simulated pH changes. Thus, digestion taking place in the gastrointestinal tract in vivo may also enhance the antioxidant properties of the extracts.

Evaluation of extracts from Gevuina avellana hulls as antioxidants.

The antioxidant activity of the extracts from Gevuina avellana hulls was evaluated and compared with that of BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole), using the beta-carotene bleaching assay, the accelerated oxidation of crude soybean oil, and the 2,2-diphenyl-beta-picrylhydrazyl (DPPH) radical scavenging method. Solvents of different polarity were used to obtain the extracts. Both the extraction yield and the antioxidant activity were strongly dependent on the solvent. The ethanol and diethyl ether soluble fractions were the most active with the beta-carotene assay. Ethanol and methanol extracts were the most active in hydrogen radical scavenging activity. Water and methanol inhibited more efficiently the oxidation of soybean oil at 70 and 80 degrees C, respectively. As a general trend, increased antioxidant activity was observed for increased extract concentration. Except the acetone extracts, all were stable after 6 months storage at 4 degrees C. The ethanol solubles from G. avellana hulls present antioxidant activity similar to that of synthetic antioxidants and to other reported residual agroindustrial materials.