Phytonutrients affecting hydrophilic and lipophilic antioxidant activities in fruits,vegetables and legumes

The antioxidant activities of fruits (n = 21), vegetables (n = 67) and legumes (n = 7) commonly consumed in Korea were determined by both the lipophilic antioxidant performance assay (LAP) and the hydrophilic oxygen radical absorbance capacity assay (ORAC). The LAP assay used the lipophilic radical initiator MeO‐AMVN [2,2′‐azobis(4‐methoxy‐2,4‐dimethylvaleronitrile)] and the lipophilic probe BODIPY 581/591 [4,4‐difluoro‐5‐(4‐phenyl‐1,3‐butadienyl)‐4‐bora‐3a, 4a‐diaza‐s‐indacene‐3‐undecanoic acid]. The ORAC assay used the hydrophilic radical initiator AAPH [2,2′‐azobis(2‐amidinopropane) dihydrochloride] and the hydrophilic probe fluorescein. In addition, the lipid‐soluble phytonutrients, carotenoids and tocopherols were determined by a reverse‐phase HPLC system using a C30 column with a UV detector. The water‐soluble phytonutrient, ascorbic acid, was analyzed using an HPLC system with an electrochemical detector. Total phenols were determined by UV spectrophotometry. Tocopherols (r = 0.774, p < 0.0001) and carotenoids (r = 0.569, p < 0.0001) were significantly correlated with LAP in total samples (n = 95). ORAC was significantly correlated with total phenols (r = 0.893, p < 0.0001), but not with ascorbic acid (r = 0.009, p = 0.929) in total samples (n = 95). These data indicate that carotenoids and tocopherols and total phenols are the major contributors to the lipophilic and hydrophilic antioxidant capacities, respectively. Therefore, the contribution of both the hydrophilic and lipophilic components of fruits and vegetables should be considered when determining the actual ‘total’ antioxidant activity of fruits and vegetables. Copyright © 2007 Society of Chemical Industry     

Influence of breadmaking on antioxidant capacity of gluten free breads based on rice and buckwheat flours

In the present study new formulations for gluten-free bread based on mixtures of rice (RF) and buckwheat flour (light buckwheat flour (LBF) or wholegrain flour (WBF)), in the proportions of 90:10, 80:20, and 70:30 were made. The gluten-free breads were investigated for their total phenolic content, rutin and quercetin contents, antioxidant activity (AOA) by β-carotene bleaching method, reducing power, scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, and chelating activity on Fe²⁺. The increased amount of LBF or WBF in the dough formulation resulted in the final products with higher antioxidant properties. Baking treatment expressed different influences on antioxidative properties of the final gluten-free product in terms of raw materials, applied recipe and antioxidative capacity in comparison to calculated values based on raw materials. Final gluten-free products were characterized by lower total phenolic and rutin contents, lower antioxidative and reducing activity and on the other hand higher DPPH and chelating activity as well as quercetin content in comparison to calculated values. Bread containing wholegrain buckwheat flour expressed in most of the cases higher values of measured antioxidative parameters than bread prepared with light buckwheat flour and thus contributes to their additional functional property.     

Evaluation of solvent effects on the DPPH reactivity for determining the antioxidant activity in oil matrix

Reactivity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical in methanol, ethanol, isopropanol, isooctane, and ethyl acetate, was evaluated to assess the antioxidant capabilities in medium chain triacylglycerol. DPPH loss values were obtained over 30 min, with sampling every 5 min. Even the same concentration of antioxidants showed different DPPH reactivity depending on solvent. In methanol, 5 min was enough for α-tocopherol to react with DPPH, whereas BHT did not react with DPPH even after 30 min. Gallate series showed higher DPPH reactivity than TBHQ, sesamol, or BHA in methanol, while lower reactivity in isooctane. Antioxidants in ethanol and isopropanol reacted with DPPH less efficiently compared to those in methanol, the exception being sesamol. DPPH reactivity of gallate series in isooctane was lower than that of sesamol, TBHQ, and α-tocopherol. Combinatorial usage of methanol and isooctane for DPPH reactivity could provide reliable information on the antioxidant capacities of chemicals in edible oils.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-020-00874-9.     

Flavonol content in the water extract of the mulberry (Morus alba L.) leaf and their antioxidant capacities

Abstract: The biological activities of the mulberry (Morus alba L.) leaf have been attributed to its flavonoid content. The water extract of the mulberry leaf (WEML) was prepared by autoclaving at 121 °C for 15 min, and the flavonol content of the WEML was determined by HPLC The WEML contained 4 flavonols in the following order: quercetin‐3‐β‐D‐glucose (QT‐G) > quercetin‐3‐O‐glucose‐6″‐acetate (QT‐GA) > rutin (RT) > quercetin (QT). In the oxygen radical absorbance capacity (ORAC) assay, QT had the highest peroxyl radical‐scavenging capacity and a similar hydroxyl radical‐scavenging capacity as its glycosides (QT‐G, QT‐GA, and RT). QT exhibited a stronger cellular antioxidant capacity (CAC) against 2,2′‐Azobis(2‐amidinopropane) dihydrochloride (AAPH)‐ and Cu²⁺‐induced oxidative stress in HepG2 cells compared to its glycosides, indicating that the intracellular antioxidant capacity of QT and its glycosides may depend upon both the permeability across the cell membrane and the peroxyl or hydroxyl radical‐scavenging capacity. Practical Application: The information presented might be used for developing mulberry leaf‐based functional foods.     

Effect of maturity stage on the content of fatty acids and antioxidant activity of ‘Hass’ avocado

Avocado (Persea americana) is an important tropical fruit and a good source of lipophilic phytochemicals such as monounsaturated fatty acids, carotenoids, vitamin E and sterols that have been inversely related to cardiovascular diseases. However, their antioxidant capacities have received far less attention compared with hydrophilic phytochemicals in this fruit. In this context, this study evaluated the effect of the stage of ripeness of ‘Hass’ avocado on the content of lipophilic and hydrophilic phytochemicals and their correlation with the antioxidant capacity. In every ripeness stage the fatty acids, total phenolic and flavonoid content as well as the antioxidant capacity were evaluated. Physiological and physico-chemical analysis were also performed including respiration rate, ethylene production, firmness, color (L*, °Hue, and Chroma), dry matter and oil content. In general, total phenols increased during ripening, while flavonoids slightly decreased. The main fatty acid identified was oleic acid (about 67-70% of total content). In general, a significant increase in monounsaturated and saturated fatty acids was observed during avocado ripening while polyunsaturated fatty acid content decreased (p < 0.05). Lipophilic extracts showed higher values of antioxidant capacity than hydrophilic, however, both extracts had similar trends for DPPH, TEAC and ORAC assays. DPPH and TEAC assays had a positive correlation with some unsaturated fatty acids. Avocado at different ripeness stages showed a better antioxidant capacity in the lipophilic fraction, which correlated with the fatty acid content evaluated.     

Effect of far-infrared radiation and heat treatment on the antioxidant activity of water extracts from peanut hulls

The antioxidant activities of peanut (Arachis hypogaea L.) hull extracts were evaluated after far-infrared (FIR) radiation or heat treatment. Peanut hulls in petri dishes were FIR-irradiated or heat-treated (150 °C) for 5, 10, 15, 20, 40 or 60 min. The water extracts (300 mg/10 mL) of peanut hulls (WEPH) were prepared and their total phenol contents (TPC), radical scavenging activity (RSA), and reducing power were determined. The antioxidant activities of WEPH increased as the time of heating or FIR-radiation increased. When peanut hulls were FIR-irradiated at 150 °C for 60 min, the values of TPC, RSA, and reducing power of WEPH increased from 72.9 to 141.6 μM, 2.34% to 48.83%, and 0.473 to 0.910, respectively, compared to the untreated controls. Heat treatment of peanut hull under the same conditions (150 °C for 60 min) also increased the TPC, RSA, and reducing power of WEPH from 72.9 to 90.3 μM, 1.90% to 23.69%, and from 0.471 to 0.718, respectively. The result indicated that FIR-radiation or heat treatment on peanut hulls increased the antioxidant activities of WEPH.     

Influence of degree of hydrolysis on functional properties,antioxidant activity and ACE inhibitory activity of peanut protein hydrolysate

Functional properties, antioxidant and Angiotensin-converting enzyme (ACE) inhibitory activities of peanut protein isolate (PPI) and peanut protein hydrolysate (PPH) prepared using Alcalase, at different (10%, 20%, 30% and 40%) degrees of hydrolysis, (DH) were investigated. Hydrolysis (at DH > 10%) significantly (p < 0.05) improved the solubility (>80%) of PPI, especially in the pH range of 4–6. However, PPI showed better emulsifying and foaming properties than PPH (p < 0.05). As DH increased, ferrous ion chelating activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and ACE inhibitory activity of PPH increased, while reducing power decreased (p < 0.05). Bleaching of beta-carotene by linoleic acid was suppressed better by PPI and PPH at 10% DH than of PPH at higher DH. Thus, the results reveal that DH affects functional properties, antioxidant and ACE inhibitory activities of peanut protein.     

Effect of hydrothermal processing on colour,antioxidant and free radical scavenging capacities of edible Irish brown seaweeds

The effect of heat processing on change in colour (ΔE), level of bioactive compounds and overall antioxidant capacity in raw and heat‐processed edible Irish brown seaweeds was investigated. Raw seaweeds were heated at 85–121 °C for 15 min in an autoclave and extracted with 60% methanol. In comparison with raw seaweeds for all the species studied, heating increased total phenol (TPC) (1.6‐ to 1.9‐fold) and total tannin (TTC) (1.3‐ to 2.6‐fold) at 95 °C, while total flavonoid (TFC) (1.6‐ to 3.3‐fold) and total sugar (TSC) (1.9‐ to 4.3‐fold) at 85 °C. Similarly, EC₅₀ value reduced in case of DPPH^? scavenging (30.7–51.8%), metal chelating ability (FIC) (27–67.8%) and H₂O₂ scavenging capacity (13.3–16.1%) at 95 °C, while reduction in lipid peroxidation (10.8–31.5%) observed at 85 °C. Results showed that heating affects content of bioactive compounds as well as beneficial biological activity associated with these compounds, which can suggest new processing for application of seaweeds extract as nutraceutical.     

Influence of drying conditions on colour,betacyanin content and antioxidant capacities in dried red-fleshed dragon fruit (Hylocereus polyrhizus)

In this study, drying of red-fleshed dragon fruit at different temperatures (40, 50, 60, 70 and 80 °C) and air velocities (1.0 and 1.5 m s⁻¹) was conducted under the specific humidity of 25 g H₂O kg⁻¹ dry air. The results showed that drying at higher temperatures resulted in shorter drying times. However, temperature and air velocity did not significantly affect the total betacyanin contents and antioxidant capacities in dried products. Seven betacyanins identified by LC-MS were betanin, isobetanin, phyllocactin, isophyllocactin, betanidin 5 –O-(6′O-3-hydroxybutyryl)-β-glucoside, isobetanidin 5 –O-(6′O-3-hydroxybutyryl)-β-glucoside and decarboxylated phyllocactin. In addition, the temperature increased the isomerisation of betacyanins. The most preferable condition for preserving the colour and betacyanin contents of red-fleshed dragon fruit was the drying at a temperature of 80 °C and air velocity of 1.5 m s⁻¹ since it could shorten the drying time and give a bright red colour to the dried product as well as it had no significant impact on the betacyanins.     

Effects of maturity stage and storage on cactus berry (Myrtillocactus geometrizans) phenolics,vitamin C,betalains and their antioxidant properties

The CIE-LAB coordinates, total phenols, betalains and vitamin C were determined in berry cactus fruit at different maturity stages, before and after storage. The contribution of those antioxidant compounds to the Trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) were assessed as well. The simple phenolics profile was determined by high performance liquid chromatography with diode array detection (HPLC-DAD). After storage, the fruit develops similar colour compared to ripe and overripe fresh fruit. Total phenols and vitamin C were reduced by up to 82.4% and 68.5%, respectively, as fruit matures and after storage. On the contrary, beta-cyanins increase up to 51.8% as fruit matures and after storage. Betalains contribute with 58.4% to TEAC and up to 43.4 to ORAC values. Gallic acid and quercetin were the major simple phenolics present. Due to the contents of antioxidant compounds and the outstanding antioxidant activities, cactus berries could contribute to health.     

The influence of roasting,pasteurisation, and storage on the polyphenol content and antioxidant capacity of California almond skins

Polyphenols and antioxidant activity of skins from California almonds subjected to roasting, pasteurisation, and storage were determined by LC-MS quantification, total phenols (TP), and ferric reducing antioxidant power (FRAP). Pasteurisation did not significantly change TP, FRAP, or flavonoids and phenolic acids (FP). Roasted almonds had 26% less TP and 34% less FRAP than raw, but equivalent FP (n = 12). Storing almonds at 4 and 23 °C for 15 mo resulted in gradual increases in FP, up to 177% and 200%, respectively (n = 13). At 4 °C and 15 mo, polyphenols increased 18-fold for p-hydroxybenzoic acid, whilst others were 45–200% higher compared to baseline values. Isorhamnetin-3-O-rutinoside accounted for 48% of the increase in FP. After 15 mo, FRAP and TP increased to 200% and 190% of initial values. Accelerated ageing of whole almonds increased FP content by 10% after 3 days, but TP and FRAP values were not significantly different from baseline to day 10. Thus, in almond skins, roasting decreases TP and FRAP but not FP, whilst storage for up to 15 mo doubles FP.     

The effects of grape seed extract fortification on the antioxidant activity and quality attributes of bread

The antioxidant activity change of breads added with grape seed extract (GSE) was investigated. The results showed that bread with the addition of GSE had stronger antioxidant activity than that of blank bread, and increasing the level of GSE addition further enhanced the antioxidant capacity of the bread. However, thermal processing caused antioxidant activity of GSE added to bread to decrease by around 30–40%. We also studied the effect of GSE on the formation of detrimental N^ε-(carboxymethyl)lysine (CML), a famous advanced glycation endproduct in bread. According to the results, GSE could reduce CML in bread and acted in a dose-dependent manner. Meanwhile, except for an acceptable colour change, adding GSE to bread had only little effect on the quality attributes of the bread. Altogether, our findings indicate that GSE-fortified bread is promising to be developed as a functional food with relatively lower CML-related health risks, yet a high antioxidant activity.     

Impact of boron, calcium and genetic factors on vitamin C, carotenoids, phenolic acids, anthocyanins and antioxidant capacity of carrots (Daucus carota)

Carrots (Daucus carota L.) were used to investigate the effects and interactions of cultivar and mineral supply on the nutritional quality (antioxidant potential, vitamin C, carotenoids and phenolic acids) of the resulting storage roots. The supplement of boron (B) and or calcium (Ca) in the feeding solutions, during plant growth, influenced the accumulation of other minerals, such as P, K, Mg, S and Na, in the storage roots (p < 0.05). When no additional B or Ca was supplied (e.g. −B or −Ca treatment), we observed 33-50% increase in the accumulated levels of α- and β-carotenes, and 45-70% increase of vitamin C. Carrots grown with no supplement of B in the nutrient solutions (e.g. −B treatment and −ve control) had significantly higher (p < 0.001) levels of total phenolic acids compared to the carrots with the supplement of B (e.g. −Ca treatment and +ve control). A strong positive correlation was observed between the total phenolic contents and ORAC values (r = 0.932) in all the cultivars. The results suggest that both cultivar and mineral supply were major determinants of nutritional quality of the carrots. The nutritional value of carrot crops (with an acceptable physical quality) can be enhanced by manipulating mineral nutrient applications.     

Effect of Maillard reaction products derived from the hydrolysate of mechanically deboned chicken residue on the antioxidant,textural and sensory properties of Cantonese sausages

Protein hydrolysates as precursors of Maillard reaction were obtained via enzymatic hydrolysis of mechanically deboned chicken residue (MDCR). The Maillard reaction products (MRPs) were prepared at 90 (M1), 100 (M2), 110 (M3) and 120 °C (M4), respectively. MRPs possessed a strong reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. According to the evolution of total free fatty acids and peroxide value of Cantonese sausage with MRPs during storage, M1 and M3 had a potent antioxidant activity (P < 0.05) due to their antioxidant abilities and inhibitory action against lipolytic enzymes. Cantonese sausages treated with M1 and M2 showed good textural and sensory properties. However, M3 and M4 had a negative (P < 0.05) effect on the flavour and texture of Cantonese sausages compared to control. The results suggested that M1 was very potential to be used to improve their antioxidant, textural and sensory quality.     

Investigation of the effects of different organosolv pulping methods on antioxidant capacity and extraction efficiency of lignin

Different organosolv pulping methods delignified raw materials (Acanthopanax senticosus remainder) were investigated, including acetone-acetic acid-water method (8/1/1, v/v/v), 1,4-butanediol-acetic acid-water method (8/1/1, v/v/v), ethanol-acetic acid-water method (8/1/1, v/v/v) and acetic acid-water method (4/1, v/v). Lignin extraction efficiency and antioxidant capacity from different organosolv methods were compared.The results showed that the lignin extraction efficiency of the 1,4-butanediol-acetic acid-water method was the highest (39%) among methods of this paper. The lignin from acetic acid-water method was the most effective free radical scavengers, whose 1,1-di-phenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity (IC₅₀) was about 0.6587 mg/ml.Acanthopanax senticosus remainder (raw materials) and pulps were characterised by scanning electron microscopy (SEM) and pulps strength properties. All lignin samples were analysed by Fourier-transform Infrared Spectroscopy (FTIR). The results showed that organosolv pulping process had large influence on pulps morphology, pulps strength properties and lignin structure.     

Comparative evaluation of the antioxidant capacity of smoke flavouring phenols by crocin bleaching inhibition, DPPH radical scavenging and oxidation potential

The antioxidant capacity of the main phenolic compounds present in wood smoke and smoke flavourings used in the food industry was investigated by three methods, based on a kinetic and thermodynamic approach: the bleaching of the carotenoid crocin, the scavenging of the DPPH radical, and the determination of the oxidation potential. The reaction with the DPPH radical was evaluated calculating the effective concentration (EC₅₀) and the antiradical efficiency (AE). The compounds tested were 2-methoxyphenols (guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-vinylguaiacol, 4-propylguaiacol, eugenol, isoeugenol, vanillin, acetovanillone, 2-propiovanillone), 2,6-dimethoxyphenols (syringol, 4-methylsyringol, 4-allylsyringol, syringaldehyde, acetosyringone) and dihydroxybenzenes (catechol, 3-methylcatechol, 4-methylcatechol, 3-methoxycatechol and hydroquinone). The trend in antioxidant capacity was similar in all the three methods, with dihydroxybenzenes > 2,6-dimethoxyphenols > 2-methoxyphenols, although some discrepancies in the ranking within the groups were present. Considering the overall ranking, isoeugenol was amongst the most active compound, like dihydroxybenzenes, evidencing the role of a conjugated double bond at para position for the stabilization of the phenoxyl radical in the radical scavenging process.     

Effects of various solvents on the extraction of antioxidant phenolics from the leaves, seeds, veins and skins of Tamarindus indica L.

The effects of solvents, of varying polarities, on the extraction of antioxidant phenolics from the leaves, seeds, veins and skins of Tamarindus indica (T. indica) were studied. The efficiencies of the solvents for extraction of the antioxidant phenolics were in the order: methanol > ethyl acetate > hexane. Phenolic content ranged from 3.17 to 309 mg of gallic acid equivalents/g. Methanol leaf extract (MEL) had the highest phenolic content and was the most potent scavenger of DPPH and superoxide radicals. Methanol vein extract had the highest ferric reducing activity whereas methanol seed extract was the most potent ABTS radical-scavenger. A positive correlation existed between phenolic content and antioxidant activities of the plant parts. HPLC analyses of MEL revealed the presence of catechin, epicatechin, quercetin and isorhamnetin. Overall, methanol was the most effective solvent for extraction of antioxidant phenolics from T. indica. T. indica, particularly the leaf, can be a useful source of natural antioxidants.     

The scavenging capacity and synergistic effects of lycopene, vitamin E, vitamin C, and β-carotene mixtures on the DPPH free radical

The biological activity of lycopene can be enhanced by the presence of these other active antioxidants such as β-carotene, vitamin E, and vitamin C. Since many of these natural antioxidants are consumed together in foods, the potential for synergistic interactions is high in the human diet. The aim of this study was to determine what concentrations and combinations of antioxidants among lycopene, vitamin E, vitamin C, and β-carotene are capable of producing synergistic antioxidant effects, based on tomato-based food products. Solutions of the scavenging capacities of lycopene, vitamin E, vitamin C, and β-carotene, alone and in different combinations were measured using the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Three different levels of each antioxidant were used. A comparison of the scavenging capacity (antioxidant activity) of the combinations of antioxidants to the arithmetic sum of the scavenging capacities of the individual antioxidants was used to calculate the synergistic effects (SEs) between the antioxidants. The results showed that the mixture that had the highest SEs (P<0.01) was the solution combining lycopene (15 μmol/L), vitamin E (5.0 μmol/L), vitamin C (0.16 μmol/L), and β-carotene (10.83 μmol/L). The results suggest that the antioxidant property of this combination was substantially superior to the sum of the individual antioxidant effects, and these interactions can enhance the antioxidant effectiveness of natural antioxidants. The results could guide in the formulation and development of functional food products that have high antioxidant potential.