The chemical diversity of natural antioxidants (AOXs) makes it difficult to
separate, detect, and quantify individual antioxidants from a complex
food/biological matrix. Moreover, the total ...antioxidant power is often more
meaningful to evaluate health beneficial effects because of the cooperative
action of individual antioxidant species. Currently, there is no single
antioxidant assay for food labeling because of the lack of standard
quantification methods. Antioxidant assays may be broadly classified as the
electron transfer (ET)- and hydrogen atom transfer (HAT)-based assays. The
results obtained are hardly comparable because of the different mechanisms,
redox potentials, pH and solvent dependencies, etc. of various assays. This
project will aid the identification and quantification of properties and mutual
effects of antioxidants, bring a more rational basis to the classification of
antioxidant assays with their constraints and challenges, and make the results
more comparable and understandable. In this regard, the task group members
convey their own experiences in various methods of antioxidants measurement.
Antioxidants are among the most studied topics both in the area of food science and nutrition. Antioxidants were firstly used as just a food preservative, then it was realized that they inhibited the ...oxidation processes not only in foods but also in human metabolism. Then, they gained the spotlight with their important roles both in foods and in human body. Consequently, significant number of research articles focusing on the antioxidant content of different foods, analytical methods for better estimation and measurement of the antioxidant capacity of foods have been publishing for years. In addition, there is a growing interest among the food scientists in improving the knowledge on the physiological effects of antioxidants in the human body. This review provides a historical overview about antioxidants covering their occurrence and roles in various foods, analytical methods for the determination of their antioxidant capacity, and their physiological effects.
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•Antioxidants are among the most studied topics in food science.•Antioxidants provide health benefits beyond preservative effects in food.•Several antioxidant compounds have been discovered from natural sources.•In vitro and in vivo assays have been developed to determine antioxidant capacity.•Understanding metabolism and digestion behavior of antioxidants gained spotlight.
Oxygen radical antioxidant capacity (ORAC) and trolox equivalent antioxidant capacity (TEAC) assays were compared to estimate the total antioxidant capacity (TAC) of orange juice, milk, and an orange ...juice-milk beverage. When the TEAC method was used with this beverage, an increase in the concentration of orange juice corresponded to an increase in TAC, but increasing the percentage of milk did not increase the TAC value. When the ORAC method was applied, it was seen that increased concentrations of juice or milk corresponded to greater antioxidant capacity. An evaluation was also made of the influence of certain compounds (ascorbic acid, gallic acid, β-carotene, lutein, zeaxanthin and albumin) with antioxidant capacity that were present in the samples studied.
Although the TEAC method is simpler and cheaper than the ORAC method, it gives an underestimate of the antioxidant capacity of foods or beverages of a more complex nature.
The ability to accurately assess the total antioxidant capacity (TAC) of Huangjiu is essential for the comprehensive assessment of its nutritional and medicinal benefits. Consequently, developing a ...rapid, sensitive and specific analytical methodology to determine TAC is an urgent research need. In this work, we explored the potential of a one-step solvothermal process, leading to the synthesis of polyoxometalates-metal-organic frameworks (POMs-MOFs), H3PW12O40 (HPW)-CuBTC materials, which possess a high surface area and considerable active sites. Our results demonstrated that HPW-CuBTC materials exhibit remarkable surface-enhanced Raman scattering (SERS) activity, capable of detecting 10–8 M methylene blue (MB). SERS activity was attributed to both the localized surface plasmon resonance (LSPR) and charge transfer (CT) synergistic enhancement mechanisms. Furthermore, HPW-CuBTC materials exhibited peroxidase (POD)-like activity, with a catalytic mechanism involving a synergistic catalytic effect between HPW and CuBTC. We developed a catechin sensor based on the POD-like properties of HPW-CuBTC, with a linear range from 4 μM to 8 μM (R2=0.98). Additionally, we utilized the HPW-CuBTC materials to construct a TAC sensing platform in Huangjiu. This work introduces new technologies and methodologies for rapid trace detection of TAC in Huangjiu, providing a valuable tool for evaluating its nutritional and medicinal benefits.
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•Constructed a Polyoxometalates-metal-organic frameworks exhibiting remarkable SERS and POD-like activity.•Developed a catechin SERS sensor utilizing the POD-like properties of HPW-CuBTC.•Established a SERS detection platform for the total antioxidant capacity of Huangjiu using HPW-CuBTC.
It would be desirable to establish and standardize methods that can measure the total antioxidant capacity level directly from vegetable extracts containing phenolics. Antioxidant capacity assays may ...be broadly classified as electron transfer (ET)- and hydrogen atom transfer (HAT)-based assays. The majority of HAT assays are kinetics-based, and involve a competitive reaction scheme in which antioxidant and substrate compete for peroxyl radicals thermally generated through the decomposition of azo compounds. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes colour when reduced. ET assays include the ABTS/TEAC, CUPRAC, DPPH, Folin-Ciocalteu and FRAP methods, each using different chromogenic redox reagents with different standard potentials. This review intends to offer a critical evaluation of existing antioxidant assays applied to phenolics, and reports the development by our research group of a simple and low-cost antioxidant capacity assay for dietary polyphenols, vitamins C and E, and human serum antioxidants, utilizing the copper(II)-neocuproine reagent as the chromogenic oxidizing agent, which we haved named the CUPRAC (cupric ion reducing antioxidant capacity) method. This method offers distinct advantages over other ET-based assays, namely the selection of working pH at physiological pH (as opposed to the Folin and FRAP methods, which work at alkaline and acidic pHs, respectively), applicability to both hydrophilic and lipophilic antioxidants (unlike Folin and DPPH), completion of the redox reactions for most common flavonoids (unlike FRAP), selective oxidation of antioxidant compounds without affecting sugars and citric acid commonly contained in foodstuffs and the capability to assay -SH bearing antioxidants (unlike FRAP). Other similar ET-based antioxidant assays that we have developed or modified for phenolics are the Fe(III)- and Ce(IV)-reducing capacity methods.
Copper (Cu) contamination in agricultural soil poses severe threats to living organisms, and possible ecofriendly solutions need to be considered for Cu immobilization, such as using biochar. A pot ...study was conducted to examine the effectiveness of biochar derived from rice straw (RSB) at various application rates (0, 2.5, 5 and 10% w/w) to mitigate possible risks of Cu solubility and its uptake by ramie (Boehmeria nivea L.) as forage. The plant growth parameters as well as soil chemical properties (pH, electrical conductivity and cation exchange capacity) notably improved with the increasing RSB application. Moreover, prominent reduction was observed in soil bioavailable Cu concentration by 96% with RSB application of 10% relative to control. In addition, Cu content in B. nivea roots, leaves and stems decreased by 60, 28 and 22%, respectively, for 10% RSB application. It was noted that chlorophyll content and gas exchange parameters in leaves were significantly higher at 10% RSB application than in control. Furthermore, 10% RSB resulted in a greater reduction in oxidative stress from the Cu in soil. Thus, soil amendment with RSB demonstrated positive results for Cu stabilization in aged Cu-contaminated soil, thereby reducing its accumulation and translocation in B. nivea and mitigating livestock feed security risks.
•The contaminated soil displayed high Cu concentration.•Rice straw biochar (RSB) increased plant growth and soil pH while reduced Cu uptake.•RSB increased photosynthesis and reduced oxidative stress.•RSB was effective in reducing extractable Cu contents.
Anthocyanins are natural flavonoids with a high antioxidant power and many associated health benefits, but most rice produce little amounts of these compounds. In this study, 141 MYB transcription ...factors in 15 chromosomes, including the nucleus-localised ZlMYB1 (Zla03G003370) and ZlMYB2 (Zla15G015220), were discovered in Zizania latifolia. Overexpression of ZlMYB1 or ZlMYB2 in rice seeds induced black pericarps, and flavonoid content, antioxidant capacity, and α-glucosidase and tyrosinase inhibition effects significantly increased compared to those in the control seeds. ZlMYB1 and ZlMYB2 overexpression induced the upregulation of 764 and 279 genes, respectively, and the upregulation of 162 and 157 flavonoids, respectively, linked to a black pericarp phenotype. The expression of flavonoid 3′-hydroxylase and UDP-glycose flavonoid glycosyltransferase, as well as the activities of these enzymes, increased significantly in response to ZlMYB1 or ZlMYB2 overexpression. This study systematically confirmed that the overexpression of ZlMYB1 and ZlMYB2 promotes flavonoid biosynthesis (especially of anthocyanins) in rice.
•Zizania latifolia has 141 MYB transcription factors in 15 chromosomes, including the nucleus-localised ZlMYB1 and ZlMYB2.•Overexpression of ZlMYB1 and ZlMYB2 increased flavonoid content and antioxidant activity.•Overexpression of ZlMYB1 and ZlMYB2 increased α-glucosidase and tyrosinase inhibition effects.•Overexpression of ZlMYB1 and ZlMYB2 increased the expression and activity of F3′H and UFGT.
The retention of bioactive compounds in the blend of wheat and rye flours and 4% roasted buckwheat hulls, dough before and after fermentation, and obtained bread were determined. In parallel, the ...content of Maillard reaction products (MRPs) and antioxidant capacity (AC) during technological steps of bread production were studied. The dough formation and fermentation process increased the content of phenolic acids and flavonoids and reduced the content of tocopherols, and no changes in glutathione as compared to the blend were noted. Moreover, the increased level of available lysine and AC were observed after dough fermentation. The baking process resulted in further increased phenolic acids, and flavonoids and decreased the tocopherols and glutathione contents. The bread was characterized by the highest values of parameters related to MRPs, such as the content of fluorescent intermediary compounds and final browning index compared to other analyzed steps.
•Roasted buckwheat hull was used for wheat/rye bread enrichment.•The antioxidant capacity of the dough increased after sourdough fermentation.•Baking reduces the glutathione content and antioxidant capacity.•An increase of the phenolic acids after baking was observed.
•Green banana flour contains high amounts of resistant starch and phenolics.•Extrusion cooking of green banana flour changes physicochemical properties.•Properties of extruded green banana flour were ...influenced by feed moisture and screw speed.•Storing of extruded flours at 4°C increased the resistant starch content.
Green banana flour was extruded through a co-rotating twin-screw extruder with constant barrel temperature. The objectives of this study were to determine the effect of extrusion cooking variables (feed moisture, FM, 20% and 50%; screw speed, SS, 200 and 400rpm) and storing of the extruded flours at 4°C for 24h on the physicochemical properties, resistant starch (RS), pasting properties and antioxidant capacities. Extrusion cooking at higher FM and lower SS increased the amylose content, which was expressed in highest RS content. Water adsorption index (WAI) and pasting properties were increased, while water solubility index (WSI), total phenolic content (TPC) and antioxidant activities (FRAP, ABTS+, DPPH) in free and bound phenolics were decreased compared to the other extruded samples. Storing the extruded flours at 4°C for 24h prior to oven drying was the main factor leading to a further increase in the content of amylose, RS, TPC and WSI values, as well as pasting properties – in particular peak viscosity. Compared to native banana flour, extrusion cooking caused significant changes in all studied properties of the extruded flours, except for soluble DF and antioxidant capacity (ABTS+ and DPPH) of bound phenolics.
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