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The reducing capacity of humic acids (HA) was evaluated by the spectrophotometric method using Fe(III) complexes with organic and inorganic ligands as oxidizing agents, depending on the medium pH and reagent concentration. The maximum sensitivity of the method was observed at pH = 5 for Fe(III) complexes with α,α′-bipyridyl and o-phenanthroline, as well as at pH = 9 for potassium hexacyanoferrate(III). The obtained results were supported by computational modeling of the complexation and dissociation processes. The number of available surface functional groups was found to decrease with an increase in the HA concentration due to the molecular aggregation, thus resulting in a lower reducing capacity. The formal redox potential of HA, measured by redox titration, ranged from 530–to 535 mV.

Sorbus subfusca (ledeb. ex. nordm.) boiss. (Sorbus subfusca) belongs to the Rosacese family. It is commonly referred to as highland rowan. It is an endemic species found only in the eastern Black Sea Region of Turkey and in a few countries on the Asian Continent. Both water (WESS) and ethyl alcohol (EESS) lyophilized forms were used as extracts. Different reducing capacity methods and radical scavenging activity methods were used to study the antioxidant activities of the extracts. Total phenolic compounds were calculated as 43.5 (WESS) and 43.0 (EESS) μg GAE/mg extract. This value is an indication that it can take place in plants with high phenolic content. Peroxidation inhibition percentages of linoleic acid emulsion at 20 µg mL-1 concentration for WESS and EESS; WESS was calculated as 70.93% and EESS as 82.63%. The high antioxidant capacity of Sorbus subfusca, an endemic species, brings up the preference of natural products as antioxidants. It is thought that these studies will draw a new path to the literature, especially alternative medicine and pharmacological studies. [ABSTRACT FROM AUTHOR]

In the present study, two spectrophotometric procedures were applied to quantify the reducing capacity (RC) of ten phenolic derivatives compounds (PC). The procedures are based on the reduction of Fe(III) by a PC with the formation of Fe(II) giving rise to water-soluble complexes with 1,10-phenanthroline (phen) or 2,2ʹ-bipyridine (bipy) ligands with absorption maximum values at 511 and 521 nm, respectively. The 4-Methoxyphenol was the most suitable phenolic compound to express these RC values. For comparison purposes, the RC values of the same PC were obtained with the reagent Folin Ciocalteu (FCR), recognised for oxidising phenols in alkaline solution. This comparative study enabled us to evaluate how the molecular structure of each PC affects the RC values, since that the number and position of functional groups are also responsible for the RC of the PCs. The RC values of six synthetic mixtures containing cresols or methoxyphenols were determined with the three procedures described above (Fe(phen)32+ and Fe(bipy)32+ complexes and FCR). Regardless of the procedure used, the absorbance values measured in these synthetic mixtures were often lower than the theoretical ones, which suggest that there may have been some chemical interaction among the components of such mixtures. As phenols were not expected in the analysed natural water samples, 3-methoxyphenol, the less reactive non-nitro PC of those evaluated in this study, was added to quantify the reducing capacity of water samples using the Fe(phen)32+and Fe(bipy)32+complexes and FCR. The results obtained showed that Fe(bipy)32+ and FCR are more suitable for this purpose. [ABSTRACT FROM AUTHOR]

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study evaluates the chemical compositions and antioxidant and antipathogenic properties of commercial orange (Citrus sinensis (L.) Osbeck) essential oils obtained using the cold-press method (EOP) and the cold-press method followed by steam distillation (EOPD). The chemical compositions of the volatilizable fractions, determined by gas chromatography-mass spectrometry, were similar in both samples. A relatively large amount of γ-terpinene was found in the EOPD (1.75%) as compared to the EOP (0.84%). Monoterpene hydrocarbons with limonene (90.4–89.8%) followed by myrcene (3.2–3.1%) as the main compounds comprised the principal phytochemical group. The non-volatile phenolics were eight times higher in the EOP than in the EOPD. Several assays with different specificity levels were used to study the antioxidant activity. Although both essential oils presented similar reducing capacities, the radical elimination ability was higher for the EOP. Regarding the antipathogenic properties, the EOs inhibited the biomass and cell viability of Staphylococcus aureus and Pseudomonas aeruginosa biofilms. Furthermore, both EOs similarly attenuated the production of elastase, pyocyanin, and quorum-sensing autoinducers as assessed using Gram-negative bacteria. The EOP and EOPD showed important antioxidant and antipathogenic properties, so they could represent natural alternatives to extend the shelf life of food products by preventing oxidation and contamination caused by microbial spoilage. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare total phenolic and flavonoid content, antioxidant and reducing activity, as well as vitamin C and E content in beebread and honey. The antioxidant activity of samples was determined by photochemiluminescence (PCL) assay, while reducing potential was measured using FRAP and ORAC assays. Vitamin C was analysed by HPLC-MS-TripleTOF method and vitamin E by HPLC-DAD. Beebread was characterised by the higher level of the total phenolic (~90%), flavonoid (~97%), vitamin C (~99%) and E (~98%) as compared to the honey. The data showed that beebread had also higher values of antioxidant activity and reducing potential by ~99% and ~41-98%, respectively, than honey. Our findings indicate that beebread is valuable source of bioactive substances, with the high beneficial properties.

The present study evaluates the chemical compositions and antioxidant and antipathogenic properties of commercial orange (Citrus sinensis (L.) Osbeck) essential oils obtained using the cold-press method (EOP) and the cold-press method followed by steam distillation (EOPD). The chemical compositions of the volatilizable fractions, determined by gas chromatography-mass spectrometry, were similar in both samples. A relatively large amount of γ-terpinene was found in the EOPD (1.75%) as compared to the EOP (0.84%). Monoterpene hydrocarbons with limonene (90.4–89.8%) followed by myrcene (3.2–3.1%) as the main compounds comprised the principal phytochemical group. The non-volatile phenolics were eight times higher in the EOP than in the EOPD. Several assays with different specificity levels were used to study the antioxidant activity. Although both essential oils presented similar reducing capacities, the radical elimination ability was higher for the EOP. Regarding the antipathogenic properties, the EOs inhibited the biomass and cell viability of Staphylococcus aureus and Pseudomonas aeruginosa biofilms. Furthermore, both EOs similarly attenuated the production of elastase, pyocyanin, and quorum-sensing autoinducers as assessed using Gram-negative bacteria. The EOP and EOPD showed important antioxidant and antipathogenic properties, so they could represent natural alternatives to extend the shelf life of food products by preventing oxidation and contamination caused by microbial spoilage.

The extraction of bioactive compounds from fruits of green coffee (Coffea canephora) was performed using solid-liquid percolation process and hydroethanolic solvent, by way of a 22 central composite rotatable design (CCRD) and response surface methodology (RSM). Bioactive contents and yield of process were the dependent variables assessed. The process yield was 25 ± 1.2%, 5-CQA, caffeine and trigonelline contents were 9751 ± 274, 6822 ± 127, 2664 ± 118 mg/100 g, respectively. The bioactive contents and reducing capacity in GCFE remained stable for 180 days at 40°C, which suggests its potential application in the pharmaceutical and food industries as an ingredient. [ABSTRACT FROM AUTHOR]

• Parkia roxburghii ; lesser known, multipurpose leguminous tree species. • Antioxidant and Free radical-scavenging potential of different parts of the plant. • Specific phenolic composition using HPLC and MS/MS. • Promotion and augmentation of scientific information of such traditional food plants for nutritional security and disease prevention and management through diets. Total phenolics in extracts of different parts of Parkia roxburghii varied from 80.1 (flowers) to 311.6 mg/ g GAE (Pods) with moderate amounts of flavonoids and high antioxidant activity (50.1–92.4%). The pods of Parkia roxburghii were found to be potent DPPH radical scavengers followed by leaves, seeds and then flowers as evident by their low IC 50 , EC 50 values and reasonably high ARP values (34.5–230.4). The pod and seed extracts exhibited good reducing power expressed as ascorbic acid equivalents (ASE/ ml) and significant protection against DNA damage caused by free radicals too. The extracts of Tree bean studied showed appreciable free radical scavenging activities through inhibition of lipid per oxidation (LPO) measured by ammonium thiocyanate assay, inhibition of hydroxyl radical observed in non-site specific and site specific assays, metal chelating capacity and superoxide radical scavenging activity. In most of the assays, the pod extracts showed higher potency in scavenging of free radicals than quercetin which was used as a standard. The specific phenolic composition of Parkia roxburghii extracts performed through HPLC and LC-MS/MS showed presence of gallic acid, caffeic acid, chlorogenic acid, ellagic acid ferulic acid. Low amounts of flavonoids like kaempferol, quercetin, diadzein and genestein were also observed in some parts of the plant. Such scientific evidences in the present investigation on the functional attributes of Parkia roxburghii , a traditional food plant would hold significant importance in genetic diversity studies and also for disease prevention and management through diets. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare total phenolic and flavonoid content, antioxidant and reducing activity, as well as vitamin C and E content in beebread and honey. The antioxidant activity of samples was determined by photochemiluminescence (PCL) assay, while reducing potential was measured using FRAP and ORAC assays. Vitamin C was analysed by HPLC--MS-TripleTOF method and vitamin E by HPLC-DAD. Beebread was characterised by the higher level of the total phenolic (~90%), flavonoid (~97%), vitamin C (~99%) and E (~98%) as compared to the honey. The data showed that beebread had also higher values of antioxidant activity and reducing potential by ~99% and ~41-98%, respectively, than honey. Our findings indicate that beebread is valuable source of bioactive substances, with the high beneficial properties. [ABSTRACT FROM AUTHOR]

Soil dissolved organic matter (DOM) plays an essential role in the Three Gorges Reservoir (TGR) as a linkage between terrestrial and aquatic systems. In particular, the reducing capacities of soil DOM influence the geochemistry of contaminants such as mercury (Hg). However, few studies have investigated the molecular information of soil DOM and its relationship with relevant geochemical reactivities, including redox properties. We collected samples from eight sites in the TGR areas and studied the link between the molecular characteristics of DOM and their electron donation capacities (EDCs) toward Hg(II). The average kinetic rate and EDC of soil DOM in TGR areas were (0.004 ± 0.001) hr−1 and (2.88 ± 1.39) nmol e−/mg DOM bulk , respectively. Results suggest that higher EDCs and relatively rapid kinetics were related to the greater electron donating components of lignin-derived and perhaps pyrogenic DOM, which are the aromatic constituents that influenced the reducing capacities of DOM in the present study. Molecular details revealed that even the typical autochthonous markers are important for the EDCs of DOM as well, in contrast to what is generally assumed. More studies identifying specific DOM molecular components involved in the abiotic reduction of Hg(II) are required to further understand the relations between DOM sources and their redox roles in the environmental fate of contaminants. Image 1 [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The acidification and reducing capacities of yoghurt bacteria were evaluated in different plant extract‐enriched milk samples. The milk samples enriched with thyme and grape seed extracts exhibited the highest values of acidification capacity for Lactobacillus delbrueckii subsp. bulgaricus (LB) (0.0065 pH unit/min) and Streptococcus thermophilus (ST) (0.0068 pH unit/min). The highest values of reducing capacity were observed in thyme (−0.98 mV/min), grape (−1.92 mV/min) and green tea (−0.75 mV/min)‐enriched samples for LB, ST and mixed culture of LB + ST, respectively. The fortification of yoghurt with plant extracts modified the acidification and reducing activities of starters, thus changing the fermentation time and quality attributes of the product. [ABSTRACT FROM AUTHOR]

Plants produce a diverse array of secondary metabolites that are generally nonessential but facilitate ecological interactions. Fruits, vegetables, seeds and nuts can accumulate bioactive secondary metabolites with health-promoting properties, including the potent antioxidant activities of phenolic compounds. Several in vitro assays have been developed to measure the polyphenol content and antioxidant activity of plant extracts, e.g., the simple and highly popular Folin-Ciocalteu (FC) assay. However, the literature contains a number of different descriptions of the assay and it is unclear whether the assay measures the polyphenol content or reducing capacity of the sample. To determine the influence of phenolic structures on the outcome of the FC assay, we tested phenols representing different subgroups (phenolic acids, flavonols, flavanols, dihydrochalcones and flavanones). We observed different results for each reference substance and subgroup. Accordingly, we concluded that the FC assay does not measure the polyphenol content of a sample but determines its reducing capacity instead. Assigning the substances to five structural classes showed that the FC results depend on the number of fulfilled Bors criteria. If a molecule fulfills none of the Bors criteria, the FC results depend on the number of OH groups. We did not find a correlation with other single electron transfer assays (e.g., ABTS and DPPH assays). Furthermore, the FC assay was compatible with all five subgroups and should be preferred over the DPPH assay, which is specific for extracts rich in dihydrochalcones or flavanones.

Highlights • Antioxidant activity of Maillard reaction products is discussed. • Maillard reaction products have superb antioxidative property in food products. • Maillard reaction products possess antibrowning effect in fruits and vegetables. • Maillard reaction products can significantly retard food oxidation. Abstract Food products containing lipids, especially unsaturated fatty acids, are prone to oxidation reactions, which lead to the formation of off-flavor, due to side-reaction products that potentially have toxic effects and reduce shelf-life. The Maillard reaction products (MRPs) are widely produced in foods containing reducing sugars and amino-bearing compounds during thermal processing and storage. MRPs possess excellent antioxidant ability in many food products, through chelation of metal ions, breakdown of radical chains and hydrogen peroxide, and scavenging of reactive oxygen species. This review presents an overview of the antioxidant activity of MRPs in model and real food systems. It also provides the pros and cons of the Maillard reaction, some available antioxidant assays to evaluate the antioxidative ability of MRPs, and parameters influencing their functional properties. In addition, metal chelation-based antibrowning ability of MRPs to inhibit the enzymatic browning reaction in fruits and vegetables is discussed. [ABSTRACT FROM AUTHOR]

Mushroom irradiation has been considered a sustainable process to generate high amounts of vitamin D2 due to the role of this vitamin for human health and of the global concerns regarding its deficient or inadequate intake. Mushrooms are also receiving increasing interest due to their nutritional and medicinal properties. However, there is still a knowledge gap regarding the effect of UV irradiation on mushroom bioactive compounds. In this study, two of the most cultivated mushroom species worldwide, Agaricus bisporus and Pleurotus ostreatus, were irradiated with UV-B, and the effect of processing was investigated on the contents of vitamin D2 as well as on antioxidant and antiglycation activities. UV irradiation increased vitamin D2 up to 57 µg/g d.w, which is an adequate level for the fortification of a number of target foods. UV irradiation decreased the antioxidant activity when measured by the Folin–Ciocalteu reagent, the 2,2-diphenyl-1-(2,4,6 trinitrophenyl) hydrazyl radical assay and the ferric ion-reducing antioxidant power assay, but did not decrease the mushroom’s ability to inhibit glycation of a target protein. These results open up a new area of investigation aimed at selecting mushroom species with high nutraceutical benefits for irradiation in order to maintain their potential properties to inhibit oxidative and glycation processes responsible for human diseases.

Abstract In this study, hydrochar was prepared from wheat straw (WS) and Spartina alterniflora (SA) biomass by hydrothermal carbonization, and further treated with HCl and NaOH washing, HNO 3 oxidization and low temperature thermal heating. The reducing capacity (RC) of sample was quantified by I 2 titration to explore how these modification methods affected the redox properties of hydrochar. The results indicated HNO 3 and thermal oxidization increased the RC of hydrochar by 2–5 folds while NaOH washing had the negative effect on samples' RC. By analyzing the excitation-emission matrix (EEM) fluorescence of alkaline extraction solution of sample, humic acid like substances generated from various methods were identified as one of the major sources for electron donating. HNO 3 oxidization could significantly increase the RC in hydrochar, which was likely resulting from the generation of alkali-soluble small molecule organic compounds. However, excessive oxidation by nitric acid with prolonged duration led to the gradual decrease in hydrochar's RC. Heating treatment caused a significant increase in the content of redox-active oxygen-containing functional groups and persistent free radicals (PFRs) in hydrochar. Even though both could donate electrons in the redox reaction with I 2 , the former was considered a greater contributor for the RC of hydrochar. From this study, the origin of RC of hydrochar can be identified as: oxygen-containing functionality, humic-like matter and PFRs. By employing different modification methods, the RC of hydrochar could be tuned by regulating the above sources. This study provided fundamental knowledges and simple routes to manipulate the redox properties of hydrochar for different environmental applications. Graphical abstract Unlabelled Image Highlights • Major source of hydrochar reducing capacity (RC): oxygen-contained functionality (OFGs) and alkali-soluble substances; • Persistent free radicals contribute less (~ 1%) to hydrochar RC; • Thermal treatment increases hydrochar reducing capacity by developing oxygen-containing functional groups and persistent free radicals; • HNO 3 oxidization increases hydrochar OFGs by generating alkali-soluble substances; [ABSTRACT FROM AUTHOR]

An alternative method for quantification of the total reducing capacity (TRC) of processed ready-to-drink fruit juices (orange, grape, peach, mango, cashew, strawberry, apple and guava) is suggested. The spectrophotometric procedure is based on the reduction of Cu(II) to Cu(I) by antioxidants (present in the samples) in aqueous buffered solution (pH 7.0), containing 4,4′-dicarboxy-2,2′-biquinoline acid (H2BCA), yielding the CuBCA23- complexes. The absorbance values at 558 nm (A558 nm) of the CuBCA23- complexes obtained with juice samples were compared with A558 nm values of the same complexes obtained with a standard ascorbic acid solution and used to quantify and express the reducing capacity of each sample. Regarding orange juices a positive relationship between the TRC values using the CuBCA23- complexes and the labelled ascorbic acid (AA) content along with the total polyphenol content (TPC) was measured. Grape juices showed the best positive correlation was verified between the TRC (with the CuBCA23- complexes) and the TPC. While other fruit juices showed good agreement of TRC values with CuBCA23- complexes and DPPH reagent. The proposed method may be applied to measure the TRC of beers and wines and also for biological samples like serum and follicular fluid. [ABSTRACT FROM AUTHOR]

Over the last years, polysaccharides have been linked to antioxidant effects using both in vitro chemical and biological models. The reported structures, claimed to act as antioxidants, comprise chitosan, pectic polysaccharides, glucans, mannoproteins, alginates, fucoidans, and many others of all type of biological sources. The structural features linked to the antioxidant action include the polysaccharide charge, molecular weight, and the occurrence of non-carbohydrate substituents. The establishment of structure/function relationships can be, however, biased by secondary phenomena that tailor polysaccharides behavior in antioxidant systems. In this sense, this review confronts some basic concepts of polysaccharides chemistry with the current claim of carbohydrates as antioxidants. It critically discusses how the fine structure and properties of polysaccharides can define polysaccharides as antioxidants. Polysaccharides antioxidant action is highly dependent on their solubility, sugar ring structure, molecular weight, occurrence of positive or negatively charged groups, protein moieties and covalently linked phenolic compounds. However, the occurrence of phenolic compounds and protein as contaminants leads to misleading results in methodologies often used for screening and characterization purposes, as well as in vivo models. Despite falling in the concept of antioxidants, the role of polysaccharides must be well defined according with the matrices where they are involved. [Display omitted] [ABSTRACT FROM AUTHOR]

The effects of single metal atom (Pt, Pd, Rh and Ru) adsorption on the photocatalytic properties of anatase TiO 2 are investigated by means of the first-principles calculations based on density functional theory (DFT). Our results show that the most stable adsorption site for single metal atom on anatase TiO 2 (101) surface is the bridge site formed by two twofold coordinated oxygen (O 2c ) atoms at the step edge. Due to the charge transfer from metal atoms to anatase TiO 2 (101) surface, the work function of adsorbed surface is significantly smaller than the clean one, indicating enhanced surface activity. Fukui functions are highly localized around the isolated metal atoms, indicating that single metal atoms on anatase TiO 2 (101) surface serve as the active reduction and oxidation sites in the photocatalytic process. Photo-induced electrons in the electronically excited TiO 2 photocatalyst can be transferred to target species through the deposited single atoms. The band structures of host TiO 2 are almost unchanged upon the adsorption, and the metal induced states are located in the band gap of the host. Remarkably, due to the metal atoms adsorption, the upward shift of conduction band edge will improve the reducing capacity of anatase TiO 2 . Moreover, when single metal atoms are adsorbed, potential energy of topmost surface Ti atoms turns to get close to the vacuum level, which significantly facilitates the electron transfer for hydrogen evolution. Results in this work provide new insights into improving the photocatalytic performance by single metal atoms adsorption. [ABSTRACT FROM AUTHOR]

Oxidation of a phenolic group in quercetin is assumed to compromise its antioxidant properties. To address this assumption, the ROS-scavenging, Folin-Ciocalteau- and Fe-reducing capacities of quercetin and thirteen structurally related flavonoids were assessed and compared with those of mixtures of metabolites resulting from their chemical and enzymatic oxidation. Regardless of the oxidation mode, the metabolites mixtures largely conserved the antioxidant properties of the parent molecules. For quercetin, 95% of its ROS-scavenging and over 77% of its Folin-Ciocalteau- and Fe-reducing capacities were retained. The susceptibility of flavonoids to oxidative disappearance (monitored by HPLC-DAD) and that of the mixtures to retain their antioxidant capacity was favourably influenced by the presence of a catechol (ring-B) and enol (ring C) function. This is the first study to report that mixtures resulting from the oxidation of quercetin and its analogues largely conserve their antioxidant properties. [ABSTRACT FROM AUTHOR]

The root of Inula racemosa is known for its antifungal, hypolipdemic and antimicrobial properties in traditional Indian Ayurvedic and Chinese system of medicine. The biological efficacy of Inula species is mainly due to the presence sesquiterpene lactone (Isoalantolactone and Alantolactone), which are reported to be inducers of Nrf2 antioxidant pathway. The investigation of properties and efficacy of root extracts of I. racemosa and their comparison was done with a view to find most efficacious extract for use at cellular level (both normal and transformed). In the present study different extracts of root of I. racemosa (aqueous, ethanolic, and 50% aqueous-ethanolic) were prepared and compared for their antioxidant potential, reducing capacity, polyphenol content and flavonoid content. Our investigations suggested that the aqueous extract possess highest antioxidant capacity and reducing potential. The polyphenol content was found to be highest in aqueous extract in comparison with other two extracts. However, all the three extracts showed less flavonoid content. Further, the preliminary phytochemical screening of all the extracts revealed the presence of terpenoids, phytosterols and glycosides. The TLC profile of ethanolic and 50% aqueous-ethanolic extracts showed the presence of alantolactone while aqueous extracts did not exhibit its strong presence. This warrants the need of more stringent techniques for characterization of aqueous extract in future. The in vitro cell based toxicity assays revealed that the aqueous extract was less toxic to kidneys cells while ethanolic extract was toxic to cells even at low concentrations. Hence, the current investigations showed better efficacy of the aqueous extract with respect to other extracts and found to be promising for its future application at in vitro levels. [ABSTRACT FROM AUTHOR]

The aim of the presented work was to develop and validate a novel high-throughput rapid Folin-Ciocalteau assay for the quantification of reducing capacity of foods based on image scanner (Image-F-C assay). The original rapid F-C assay using a 96-well plate was improved by adding a neutralization step that stabilizes the formed color, enabling image acquisition using a flatbed scanner. Although the scanner has been already used in other analytical applications, no analysis has been reported regarding the effect of the scanner model, the plate orientation or the reaction volume. In the present study, we establish that the mentioned parameters do affect the linearity and precision of image based Folin-Ciocalteau assay, and provide the optimal scanning conditions for the analyzed scanner models. Euclidean distance calculated from R (Red), G (Green) and B (Blue) values was chosen, based on linearity and sensitivity, in order to quantify the reducing capacity. An in-house program using free ImageJ macro language was written to calculate automatically the RGB values of each well. The Image-F-C assay is linear within the range of 0–20 mg L −1 of gallic acid ( R 2 ≥0.9939). We compared reducing capacity values from real samples quantified by the image F-C assay and by a microplate reader and an inter-day relative standard error<8% was observed. Bland-Altman and correlation analyzes showed that there were no significant differences between the two methods. [ABSTRACT FROM AUTHOR]

The radical scavenging activity (RAS), chain-breaking activity, H2O2-scavenging, reducing capacity and total phenolics of four types of onions (Green onion, Yellow, Red and Purple) and garlic were investigated. Total phenolics varied from 30 mg (green onion) to 49 mg.100 g-1 fresh weight (garlic). Garlic extract showed the highest RAS, while green onion showed the lowest one. The chain-breaking activity of green onion extract was higher (0.48) than garlic extract (0.029). Chain-breaking activity of yellow, red and purple onion extracts was 0.19, 0.048 and 0.032 respectively. However, heating treatment (90 ºC, 3h) caused an increase in this activity. Low ability of green onion extract to scavenge hydrogen peroxide was noted (35%), whereas high ability was noted in other onion and garlic extracts and ranged from 60 to 90%. The lowest reducing capacity was noted in green onion extract (18%), whereas the highest in garlic extract (196%). Statistically, high significant correlations were observed between total phenolics content and reducing power, scavenging of hydrogen peroxide and chain-breaking activity of extract