Effects of genotype, location and baking on the phenolic content and some antioxidant properties of cereal species

In order to assess the effect of genotype, location and their interaction on total phenolic content (TPC) of chemical extracts, the whole grains of durum and soft wheat, oat, barley and triticale were evaluated. Data showed differences in phenolic content of chemical extracts among cereal species and the analysis of variance confirmed the key role of location. Besides TPC and trolox equivalent antioxidant capacity (TEAC) values assessed by chemical extraction were compared with those obtained with an in vitro digestive enzymatic extraction. Differences were found between methanolic and enzymatic extracts, and data confirmed that enzymatic technique enhanced extraction of antioxidants but pointed out lesser differences among cereal types. The breads obtained by flours enriched with different levels of bran were also evaluated. Chemical extracts highlighted the increasing levels of antioxidants according to bran enrichments, without pointing out changes caused by baking. The enzymatic extraction instead did not show differences regarding to bran enrichments, but documented a loss in antioxidant properties of breads in respect to corresponding flours. On the other hand the scarce differences between flours and corresponding breads did not allow asserting that baking modified the TPC and TEAC, independently of the extraction methods used. Indeed, during baking process, also the observed phenolic acids profile variations did not vary the antioxidant properties of breads.     

Characterization of antioxidant olive oil biophenols by spectroscopic methods

BACKGROUND: Olive oil contains numerous phenolic components with well‐recognized health‐beneficial activity. The major phenolic compounds present in olives and virgin olive oil—hydroxytyrosol, oleuropein and the oleuropein aglycones 3,4‐DHPEA‐EA and 3,4‐DHPEA‐EDA—as well as some of their metabolites were studied in the present work, regarding their main structural preferences. Vibrational spectroscopy (Raman) coupled to theoretical methods were used, aiming at fully characterizing the systems and therefore enabling their quick and reliable identification in food samples. RESULTS: The Raman data, assisted by the theoretical simulations, allowed us to obtain the main geometrical and spectroscopic features of the olive oil constituents under study, which determine their known antioxidant and chemoprotective properties. In fact, it was verified that the spectra comprise distinctive bands for each compound, allowing their ready detection and differentiation. CONCLUSION: This is the first reported study on the structural behaviour of olive oil phenolic compounds, and it established Raman spectroscopy as a rapid, non‐destructive and reliable analytical technique for identifying these bioactive components in dietary extracts. It can surpass other analytical methods currently used, once it allows the concomitant identification of several olive oil components in a particular sample. Copyright © 2010 Society of Chemical Industry     

Phenolic compounds from winemaking waste and its antioxidant activity towards oxidation of rapeseed oil

The effects of extraction parameters on bioactive compound contents of winemaking waste extracts (WWE) and its effect on rapeseed oil oxidative stability were evaluated. Research showed that the total phenols and anthocyanin contents and antioxidant activity (AA) of WWE significantly depended on the extraction parameters. Increasing the temperature (60 °C) and time (5 h) of extraction and an addition of water to ethanol statistically improved the rate of active component extraction. HPLC analysis showed that procyanidin B_2, catechin, gallic acid, γ‐resorcylic acid and p‐coumaric acid were the major phenolic compounds of WWE. Important correlations between total phenolic compounds quantified by HPLC and both DPPH and (ferric reducing antioxidant power) (FRAP) values were found. WWE added to the oil at three different levels clearly slowed down the process of fatty acid oxidation, inhibiting hydroperoxide formation by about 86%, comparable with BHT, while it was more effective than that of α‐tocopherol. When using volatile compound formation as a marker of lipid oxidation, WWE at the level of 2000 ppm were the most effective inhibitors of the decomposition of hydroperoxides. The research showed that the WWE are a rich source of phenolic compounds with powerful antioxidant activities and are suitable for preventing rapeseed oil oxidation.     

A comparative study on the antioxidant properties of Slovakian and Austrian wines

The antioxidant properties of 86 wine samples (35 white and 17 red from the Slovak, and 12 white and 22 red from the Burgenland, regions) were investigated by Electron Paramagnetic Resonance (EPR) spectroscopy using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt cation radical (ABTS⁺) as oxidants. Generally, the red wines showed, on the average, more than 10 times higher antioxidant activity towards ABTS⁺ than the white wines. A similar ratio was found for the total phenolics content. A linear correlation was found between the antioxidant activities determined by DPPH and ABTS⁺ and the phenolics concentration. This trend is supported by the significant difference of the total integral value of the aromatic region in ¹H NMR (Nuclear Magnetic Resonance) spectra between the red and white wine samples. The content of the phenolic acid components of 16 selected wine samples determined by High Performance Liquid Chromatography (HPLC) correlates with the antioxidant activities. No significant differences were found between Slovakian and Austrian wines.     

Bioactive components and functional properties of biologically activated cereal grains: A bibliographic review

Whole grains provide energy, nutrients, fibers, and bioactive compounds that may synergistically contribute to their protective effects. A wide range of these compounds is affected by germination. While some compounds, such as β-glucans are degraded, others, like antioxidants and total phenolics are increased by means of biological activation of grains. The water and oil absorption capacity as well as emulsion and foaming capacity of biologically activated grains are also improved. Application of biological activation of grains is of emerging interest, which may significantly enhance the nutritional, functional, and bioactive content of grains, as well as improve palatability of grain foods in a natural way. Therefore, biological activation of cereals can be a way to produce food grains enriched with health-promoting compounds and enhanced functional attributes.     

Investigation of plant extracts for the protection of processed foods against lipid oxidation. Comparison of antioxidant assays based on radical scavenging, lipid oxidation and analysis of the principal antioxidant compounds

 Antioxidant activities of plant extracts from spices, coffee, tea, grape skin, and tomato peel slurry were evaluated using a number of analytical methods including the quantification of principal compounds. Similar rankings in the activities of these extracts were obtained by evaluating their efficiencies as scavengers of stable free radicals: Fremy's salt, galvinoxyl or α,α-diphenyl-β-picrylhydrazyl (DPPH). Similar results were obtained with the lipid oxidation assays based on thermal acceleration (formation of conjugated dienes in methyl linoleate at 40  °C or the Rancimat test at 100  °C with lard). Rankings of the extract activity obtained by scavenging of hydroxyl radicals generated in the Fenton reaction were similar to those obtained by an oxygen consumption assay with linoleic acid as substrate and metmyoglobin as catalyst. However, the results of the latter two assays differed from those of the other assays. In the overall ranking, coffee and rosemary extracts were amongst the most potent extracts whereas the tomato peel slurry showed no activity. Received: 16 February 2000 / Revised version: 7 July 2000     

Phenolic compounds,lycopene and antioxidant activity in commercial varieties of tomato (Lycopersicum esculentum)

Nine commercial varieties of tomato (Rambo, Senior, Ramillete, Liso, Pera, Canario, Durina, Daniella and Remate) produced in Spain were analysed for their lycopene content, content of phenolic compounds and antioxidant capacity. The phenolic compounds were characterised as flavonoids (quercetin, kaempferol and naringenin) and hydroxycinnamic acids (caffeic, chlorogenic, ferulic and p‐coumaric acids). Antioxidant activity was measured using the DPPH and ABTS assays. The concentrations of lycopene and the various phenolic compounds as well as the antioxidant activity were significantly influenced by the tomato variety. Quercetin, the most abundant flavonoid, was found in concentrations ranging between 7.19 and 43.59 mg kg^?1 fresh weight, while naringenin levels were lower than 12.55 mg kg^?1. The most abundant hydroxycinnamic acid was chlorogenic acid, with values ranging from 14 to 32 mg kg^?1 fresh weight, followed by caffeic acid, while p‐coumaric and ferulic acids showed similar concentrations lower than 5 mg kg^?1. The highest content of lycopene was found in Ramillete, Pera and Durina (>50 mg kg^?1 fresh weight), while the concentration in the other varieties was between 50 and 30 mg kg^?1, with the exception of Liso (less than 20 mg kg^?1). The antioxidant activity of tomato extracts varied with the tomato variety and the assay method used. Individual compounds found to be significantly related to antioxidant capacity were lycopene and ferulic and caffeic acids, but not quercetin and chlorogenic acid. © 2002 Society of Chemical Industry     

Analysis of volatile compounds and antioxidant activity in rice extracts (Oryza sativa L.) extracted by various conditions

This study focused on the analysis of the volatiles present in rice extracts (Oryza sativa L.) produced under various extraction conditions (i.e. the range of temperature was 50, 60 and 70 °C, and particle size was whole, 355, and 710 μm) The main volatiles identified were ethyl palmitate, benzenemethanol, nonanal, hexanal and 3-methyl-1-butanol. The highest levels of flavour compounds extracted from rice cultivated in Icheon and Cheorwon were recorded at an extraction temperature of 70 and 60 °C, respectively, and at a rice particle size of 355 μm. Non-volatile rice extracts were tested for antioxidant activity using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The antioxidant activity of Icheon rice extracts at a concentration of 2000 ppm was found to be 84.33 and 84.39% in the DPPH and ABTS assays, respectively.     

Quality parameters and antioxidant and antibacterial properties of some Mexican honeys

A total of 14 Mexican honeys were screened for quality parameters including color, moisture, proline, and acidity. Antioxidant properties of complete honey and its methanolic extracts were evaluated by the DPPH, ABTS, and FRAP assays. In addition, the antimicrobial activity of complete honeys against Bacillus cereus ATCC 10876, Listeria monocytogenes Scott A, Salmonella Typhimurium ATCC 14028, and Sthapylococcus aureus ATCC 6538 was determined. Most of honeys analyzed showed values within quality parameters established by the Codex Alimentarius Commission in 2001. Eucalyptus flower honey and orange blossom honey showed the highest phenolic contents and antioxidant capacity. Bell flower, orange blossom, and eucalyptus flower honeys inhibited the growth of the 4 evaluated microorganisms. The remaining honeys affected at least 1 of the estimated growth parameters (increased lag phase, decreased growth rate, and/or maximum population density). Microorganism sensitivity to the antimicrobial activity of honeys followed the order B. cereus > L. monocytogenes > Salmonella Typhimurium > S. aureus. The monofloral honey samples from orange blossoms, and eucalyptus flowers demonstrated to be good sources of antioxidant and antimicrobial compounds. All the Mexican honey samples examined proved to be good sources of antioxidants and antimicrobial agents that might serve to maintain health and protect against several diseases. PRACTICAL APPLICATION: The results of the study showed that Mexican honeys display good quality parameters and antioxidant and antimicrobial activities. Mexican honey can be used as an additive in the food industry to increase the nutraceutical value of products.     

Antioxidant properties of garden strawberry leaf extract and its effect on fish oil oxidation

The present study characterises garden strawberry leaf extract and reports its effect on shelf life and quality characteristics of fish oil. Radical scavenging capacity of the extract in DPPH^? and ABTS^?+ assays was equivalent to 1207 and 1579 μmol g^?1 of trolox equivalents, respectively, total phenolic content was 257 mg g^?1 of gallic acid equivalents. Phenolic and volatile constituents were analysed by liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS). The extract was added to fish oil and its oxidation was followed during 42 days: peroxide, p‐anisidine values and hexanal concentration were lower in the samples with extract, particularly at the end of storage. The effect of extract on fatty acid composition was not significant, however the changes in the percentages of some individual acids were observed. Fish oil containing 5% of extract had lower levels of lipid oxidation in comparison to other samples. The results indicate that strawberry leaves could be a potential source of natural antioxidants.     

Screening of bioactive lipids and radical scavenging potential of some solanaceae plants

Gas-liquid chromatography (GLC) and normal-phase high performance liquid chromatography (HPLC) were used to analyse fatty acids and fat-soluble bioactives of the seeds of four Datura species (D. stramonium, D. metel, D. tatula, D. innoxia) and two Hyoscyamus species (H. muticus, H. niger). The amounts of n-hexane extract were found to be between 5.50% and 12.6%. The major fatty acid was linoleic acid followed by oleic, palmitic and stearic acids. The crude n-hexane extract was characterised by a relatively high amount of phytosterols, wherein the sterol markers were stigmasterol, β-sitosterol, lanosterol, Δ5-avenasterol and sitostanol. In all plant extracts γ-tocopherol was the major component present accounting for more than 80% of total tocopherols detected. When different extracts were compared for their radical scavenging activity (RSA) toward the stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, D. Innoxia exhibited a stronger RSA.     

Effect of solvent type on the extractability of bioactive compounds,antioxidant capacity and colour properties of natural annatto extracts

This study was conducted to obtain annatto extracts with both high antioxidant capacity and colour potential using solvents of different polarities (water, ethanol/water, ethanol, ethanol/ethyl acetate and ethyl acetate). The highest levels of total phenolic compounds were found in the water, ethanol/water and ethanol extracts (0.5 mg GAE mL^?1), and the highest level of bixin was found in the ethanol/ethyl acetate extract (5.2 mg mL^?1), which was characterised as the reddest and the most vivid one (a* = 40.5, h° = 46.1, C* = 58.4). The ethanol/ethyl acetate extract also showed the highest antioxidant activity (4.7 μm TEAC mL^?1) and the highest percentage of tryptophan protection against singlet oxygen (63.6%). On the other hand, ethyl acetate and ethanol/water were the least effective solvents for the extraction of phenolic compounds and bixin, respectively. According to the multivariate statistical analysis, ethanol/ethyl acetate and ethyl acetate were the most promising solvents to obtain annatto extracts with both antioxidant and colour properties.     

Physical,nutritional and antioxidant properties of Zimbabwean bambara groundnut and effects of processing methods on their chemical properties

This study examined the physical, nutritional and antioxidant properties of popular Zimbabwean bambara groundnut landraces and the effects of different processing methods on their chemical properties. The physical, nutritional and antioxidant properties of grains of the bambara landraces differed significantly with grain type, and the processing methods investigated had varying effects on the chemical properties of the grains. Bambara had significantly lower protein content than the reference common bean. Protein and carbohydrate content of the grains increased upon dehulling, while tannin (approx. 36%), total phenolic content (approx. 83%) and antioxidant activities (approx. 18%) decreased. Roasting alone seemed to have little or no effect on the nutrient content of the grains, while sifting significantly reduced the phenolic content and antioxidant activity of all the dehulled and roasted samples. The results indicate that roasting bambara grains would be a suitable method as it is relatively more conservative of nutrients and antioxidants than the other methods investigated.     

Polyphenol composition and antioxidant capacity in pulp and peel of apricot fruits of various varieties and maturity stages at harvest

Polyphenol composition and antioxidant capacities of peel and pulp tissues of six apricot varieties were determined. Variations in polyphenol and antioxidant capacity based on variety (early‐maturing varieties and late‐maturing varieties) and harvest maturity (green mature and full mature) were assessed. The results of principal component analysis revealed that (+)‐catechin made the most important contributions to the antioxidant capacities of the pulp. As the (+)‐catechin content in ‘Dajie’ apricot decreased by 36.8% from green mature to full mature, the antioxidant capacities determined by ABTS free radical scavenging assay, DPPH free radical scavenging assay and cupric ion reducing antioxidant capacity assay decreased by 50.0%, 45.2% and 45.8%, respectively. Levels of phenolic compounds in the apricot peels were approximately 2–4 times higher than those of the pulps. Quercetin‐3‐rutinoside may be substantially responsible for the antioxidant capacities of the peels. The late‐maturing varieties tended to have higher levels of phenolic compounds and higher antioxidant capacities than the early‐maturing varieties. The antioxidant capacities in green mature apricots were much higher than those of full mature apricots.     

Free radical scavenging and antioxidant activity of 5,7,3′,4′-hydroxy-substituted flavonoids

The antioxidant efficiencies of 5,7,3′,4′-hydroxy-substituted flavonoids were examined. The tested compounds (quercetin, luteolin, taxifolin, (+)-catechin and eriodictyol) were selected with a view to their C-ring differentiated pattern. Each one was added in cottonseed oil at equimolar amounts and the retardation of lipid peroxidation was estimated by means of peroxide value. Furthermore, their ability to scavenge DPPH radical was studied in two solvents (methanol and ethyl acetate) and the DPPH method proved a satisfactory prediction test for the antioxidant action of flavonoids in oils when methanol was used as the reaction media. Furthermore, the comparison of the C-ring structural element contribution to the antioxidant action revealed the full substitution to be the most important followed by the 3-OH and 2,3-double bond in the presence of the 4-carbonyl. Concerning the monosubstituted flavonoids, the 4-carbonyl group induced minor activity, whereas the 3-OH increased significantly the antiradical and antioxidant action.     

Determination of oil palm fruit phenolic compounds and their antioxidant activities using spectrophotometric methods

There is scarce information on the phenolics of oil palm fruits (Elaeis guineensis). In this study, phenolics were extracted from oil palm fruits and analysed using spectrophotometry for information on the different types of palm phenolics and their antioxidative activities. Analyses of the total phenolic content (TPC), total flavonoid content (TFC), o‐diphenols index, hydroxycinnamic acid index, flavonols index and phenol index showed ranges between 5.64 and 83.97 g L^?1 gallic acid equivalent (GAE), 0.31–7.53 g L^?1 catechin equivalent, 4.90–93.20 g L^?1 GAE, 23.74–77.46 g L^?1 ferulic acid equivalent, 3.62–95.33 g L^?1 rutin equivalent and 15.90–247.22 g L^?1 GAE, respectively. The antioxidant assay, 2,2‐diphenyl‐2‐picrylhydrazyl radical scavenging assay, showed antioxidative activities in all the extracts with results ranging from 4.41 to 61.98 g L^?1 trolox equivalent. The high antioxidant activities of the oil palm fruit phenolics were also found to increase with increasing TPC and TFC.     

Phenolic composition and free radical scavenging activity of different apple varieties in relation to the cultivar,tissue type and storage

The aim of this research was to evaluate the influence of genotype, tissue type and cold storage on the bioactive compounds content and on the antiradical activity (AA) of different apple cultivars (Golden cl. B, Fuji cl. Kiku8, Braeburn cl. Hillwell). The content of analysed phyto-compounds depended on the clone, on the part of fruit, and to a minor extent, on the storage. For EC₅₀ data, the cultivar represented the main source of variation and the interaction with the type of tissue, was significant. The AA of apples, measured by means of the DPPH test, was highly correlated to the flavan-3-ols content, which represents a good predictor of the apple antiradical power. The new Braeburn’s clone, the Hillwell, had the worst AA related to a minor phyto-chemical content. Also, its phenolic content was dramatically reduced after cold storage (flesh: −50%; peels: −20%; p < 0.05). Obtained results underlined the key role of the genotype on the content of the nutraceutical power of apples, which is important to improve their quality and consumption benefits, suggesting to the breeders to pay more attention to the potential healthy compounds in the development of new hybrids.