Discrimination between arabica and robusta coffee species on the basis of their tocopherol profiles

The tocopherol profiles of arabica and robusta coffee beans, both green and roasted, were ascertained. A solid-liquid micro-extraction method was used, and the quantification performed by normal-phase HPLC/diode-array/fluorescence detection. Regarding green arabicas, the mean contents were 2.7 ± 0.4 mg/100 g, for α-tocopherol, and 8.0 ± 0.9 mg/100 g, for β-tocopherol. For green robustas, mean values of 1.7 ± 0.3 and 2.1 ± 0.3 mg/100 g were found for α- and β-tocopherol, respectively. Generally, more than 90% of tocopherols remained after the roasting procedure, except for β-tocopherol in robustas, whose mean degradation was approximately 25% when expressed as dry weight. No γ-tocopherol was detected in any sample. The results show that tocopherol profile could be useful in the discrimination of arabica and robusta coffees (either green or roasted).     

Method development and validation for isoflavones quantification in coffee

This paper reports the development and validation of an analytical method to quantify three isoflavones (daidzein, genistein and formononetin) in coffee beans and coffee brews, by HPLC with diode-array detection. The aglycones were released by methanolic acid hydrolysis in the presence of the antioxidant BHT and the internal standard 2′-methoxyflavone. The method showed high correlation coefficients (r > 0.999) for standards subjected to the entire procedure. For samples, good intra- and inter-day precisions (<8%), and accuracies (recoveries of 95 ± 1% for ground coffee and 92 ± 2% for coffee brew) were achieved. Detection and quantification limits ranged from 5 to 8 ng/mL and from 14 and 25 ng/mL, respectively. The proposed method proved to be sensitive, precise and accurate.     

Solid phase extraction in the analysis of squalene and tocopherols in olive oil

Solid phase extraction (SPE) is only marginally employed in the official EU methods on the characteristics of olive oil. In the present study a SPE procedure was optimised for the subsequent extraction of squalene and α-tocopherol prior to HPLC of triacylglycerols. Squalene elution from a silica cartridge was achieved with 10 ml of n-hexane whereas α-tocopherol was isolated using 2 × 10 ml n-hexane/diethylether, 99:1, v/v. For both constituents, the precision of the SPE procedure (squalene: CV % = 4.4–6.4, n = 5; α-tocopherol: CV% = 5.3, n = 7) and the mean recovery (squalene: 88 ± 9% and 85 ± 4% for 700 and 4000 mg/kg levels of addition; α-tocopherol: 88 ± 6% and 91 ± 3% for 70 and 225 mg/kg levels of addition, respectively) were satisfactory with regards to those reported using other HPLC procedures with or without sample pretreatment. The results of the present study can be proved useful in the official control of virgin olive oil.     

Occurrence of furan in coffee from Spanish market: Contribution of brewing and roasting

In this work, we evaluated the occurrence of furan in brews obtained from regular, decaffeinated, and instant coffee and commercial packed capsules. For this purpose, a previously developed automated headspace solid-phase microextraction method coupled to gas chromatography–mass spectrometry (HS-SPME-GC–MS) was used. Initially, the influence of HS-SPME conditions on furan formation was evaluated. In addition, the effect of roasting conditions (temperature and time) used for coffee beans on furan formation was also studied. We found that low temperature and long roasting time (140 °C and 20 min) decreases the final furan content. Furan concentrations in regular ground coffee brews from an espresso coffee machine were higher (43–146 ng/ml) than those obtained from a home drip coffee maker (20 and 78 ng/ml), while decaffeinated coffee brews from a home drip coffee maker (14–65 ng/ml) showed a furan concentration similar to that obtained from regular coffee. Relatively low concentrations of this compound (12–35 ng/ml) were found in instant coffee brews, while commercial packed coffee capsules showed the highest concentrations (117–244 ng/ml). Finally, the daily intake of furan through coffee consumption in Barcelona (Spain) (0.03–0.38 μg/kg of body weight) was estimated.     

Tocopherol speciation as first screening for the assessment of extra virgin olive oil quality by reversed-phase high-performance liquid chromatography/fluorescence detector

A method based on reversed-phase high-performance liquid chromatography with fluorescence detector has been developed for the determination of tocopherols in vegetable oils. Oils were diluted in acetonitrile/tetrahydrofuran (THF) and injected directly onto HyPurity C₁₈ column. Methanol and THF (90:10) mixture was used as a mobile phase. Tocopherols were detected by fluorescence detector. The method had good limit of detection (LOD) (7 ng/g for α-tocopherol and 6 ng/g for β-, γ- and δ-tocopherols) and reproducibility (CV% < 2.8%).     

Potentials to differentiate milk composition by different feeding strategies

To investigate the effect of the dietary intake of the cow on milk composition, bulk-tank milk was collected on 5 occasions from conventional (n = 15) and organic (n = 10) farms in Denmark and on 4 occasions from low-input nonorganic farms in the United Kingdom, along with management and production parameters. Production of milk based on feeding a high intake of cereals, pasture, and grass silage resulted in milk with a high concentration of α-linolenic acid (9.4 ± 0.2 mg/kg of fatty acids), polyunsaturated fatty acids (3.66 ± 0.07 mg/kg of fatty acids), and natural stereoisomer of α-tocopherol (RRR-α-tocopherol, 18.6 ± 0.5 mg/kg of milk fat). A milk production system using a high proportion of maize silage, by-products, and commercial concentrate mix was associated with milk with high concentrations of linoleic acid (LA; 19.7 ± 0.4 g/kg of fatty acids), monounsaturated fatty acids (27.5 ± 0.3 mg/kg of fatty acids), and a high ratio between LA and α-linolenic acid (4.7 ± 0.2). Comparing these 2 production systems with a very extensive nonorganic milk production system relying on pasture as almost the sole feed (95 ± 4% dry matter intake), it was found that the concentrations of conjugated LA (cis-9,trans-11; 17.5 ± 0.7 g/kg of fatty acids), trans-11-vaccenic acid (37 ± 2 g/kg of fatty acids), and monounsaturated fatty acids (30.4 ± 0.6 g/kg of fatty acids) were higher in the extensively produced milk together with the concentration of antioxidants; total α-tocopherol (32.0 ± 0.8 mg/kg of milk fat), RRR-α-tocopherol (30.2 ± 0.8 mg/kg of milk fat), and β-carotene (9.3 ± 0.5 mg/kg of milk fat) compared with the organic and conventional milk. Moreover, the concentration of LA (9.2 ± 0.7 g/kg of fatty acids) in milk from the extensive milk production system was found to approach the recommended unity ratio between n-6 and n-3, although extensive milk production also resulted in a lower daily milk yield.     

Fatty acid profile and stability of oil from the belly flaps of Nile perch (Lates niloticus)

Oil extracted from the belly flaps of Lake Victoria Nile perch (Lates niloticus) was evaluated for fatty acid composition, contents of vitamin A, β-carotene and α-tocopherol, and oxidative stability. The oil was found to contain substantial amount of palmitic, palmitoleic, stearic, oleic, docosapentaenoic and docosahexaenoic fatty acids (FAs) and had high vitamin A content (3.94 ± 0.02 to 5.90 ± 0.02 mg/100 g of oil). Docosahexaenoic acid (10.45 ± 0.38%), docosapentaenoic acid (5.30 ± 0.60%) and eicosapentaenoic acid (3.63 ± 0.05%) were the most dominant polyunsaturated fatty acids (PUFAs). Ratios of PUFAs to saturated FAs were in the range 0.68 ± 0.02 to 0.74 ± 0.03, while the ratio of total ω-3 FAs to total ω-6 FAs was 0.85 ± 0.02 to 0.95 ± 0.08. The oils showed exceptional resistance to accelerated oxidation at 65 °C probably because of its high content of β-carotene (2.93 ± 0.03 to 4.69 ± 0.01 mg/100 g of oil) and α-tocopherol (2.11 ± 0.03 to 11.4 ± 0.92 mg/100 g of oil). From the results, it can be concluded that Nile perch oil is a rich source of essential fatty acids and vitamin A.     

The in vitro antioxidative properties of the essential oils and methanol extracts of Satureja spicigera (K. Koch.) Boiss. and Satureja cuneifolia ten

This study was designed to examine the in vitro antioxidant activities of the essential oil and methanol extracts of Satureja spicigera and S. cuneifolia from Turkish flora. GC and GC/MS analysis of the essential oils resulted in the identification of 40 and 29 compounds, representing the 99.4% and 99.5% of the oils, respectively. Major constituents of the oils were carvacrol (42.5% and 67.1%), γ-terpinene (21.5% and 15.2%) and p-cymene (20.9% and 6.7%), respectively. Methanol extracts were also obtained from the aerial parts of the plants. The samples were subjected to a screening for their possible antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene–linoleic acid assays. In general, samples obtained from S. cuneifolia exerted greater antioxidant activities than did those obtained from S. spicigera. In the DPPH test system, free radical-scavenging activity of S. spicigera oil was determined to be 127 ± 1.63 μg/ml, whereas IC₅₀ value of S. cuneifolia was 89.1 ± 2.29 μg/ml. In the β-carotene–linoleic acid test system, antioxidant activities of the oil were 81.7 ± 1.14% and 93.7 ± 1.83%, respectively. Antioxidant activities of the synthetic antioxidant, BHT, ascorbic acid, curcumin and α-tocopherol were also determined in parallel experiments.     

Dietary fiber,amino acid,fatty acid and tocopherol contents of the edible seaweeds Ulva lactuca and Durvillaea antarctica

The nutritional composition of the edible seaweeds Durvillaea antarctica (frond and stem) and dried Ulva lactuca was determined, including the soluble (SDF), insoluble (IDF) and total (TDF) dietary fiber content, amino acid and fatty acid profiles along with tocopherols and tocotrienols (pro-vitamin E). Results show that U. lactuca contained 60.5 ± 1.5%, and D. antarctica frond and stem 71.4 ± 1.5% and 56.4 ± 0.4% of TDF, respectively. Levels for the different amino acids ranged from 0.7 ± 0.1 to 1508.4 ± 9.5 (mg/100 g protein) in U. lactuca, from 0.2 ± 0.0 to 2019.9 ± 5.2 (mg/100 g protein) in D. antarctica (stem), and from 0.3 ± 0.0 to 1052.6 ± 2.9 (mg/100 g protein) in D. antarctica (leaves). In the three seaweeds, the most abundant fatty acid was C18:1ω9cis which in U. lactuca accounted for 27.42 ± 2.60%; in D. antarctica it was 25.36 ± 3.10% and 25.83 ± 2.52% in leaves and stem, respectively. In D. antarctica, γ-tocotrienol (651.7 ± 5.1 mg/kg), δ-tocopherol (245.9 ± 3.7 mg/kg) and α-tocopherol (179.4 ± 12.1 mg/kg) were determined in fronds, α-tocopherol (258.0 ± 7.2 mg/kg) was determined in stem. U. lactuca, showed a high γ-tocopherol level (963.5 ± 3.8 mg/kg).     

Lead and cadmium concentrations in goat,cow, sheep,and buffalo milks from different regions of Iran

In total, 137 goat, cow, sheep, and buffalo milk samples were collected in different regions of Iran and analysed to determine concentrations of lead and cadmium by a graphite furnace atomic absorption spectrometric method. The mean recovery of the analytical method was 96.3% and 104% for cadmium and lead, respectively. The mean lead and cadmium contents obtained from 137 samples were 1.93 ± 1.48 (range: 0.18–6.11 ng/ml) and 9.51 ± 4.93 ng/ml (range: 1.84 ng/ml–30.50 ng/ml), respectively. Lead concentration in 8.1% of sheep and 1.9% of cow milk samples was higher than the newly established Codex standard. The mean concentrations of cadmium and lead in animals aged ?3 years (n = 80; 1.40 ± 1.05 ng/ml and 7.91 ± 3.60 ng/ml, respectively) were lower than in animals aged >3 years (n = 58; 2.69 ± 1.67 ng/ml and 11.8 ± 5.71 ng/ml, respectively).     

Acrylamide in espresso coffee: Influence of species,roast degree and brew length

Espresso coffees were analysed for acrylamide contents by matrix solid-phase dispersion and GC–MS. The influence of coffee species, roast degree, and brew length were ascertained. Mean acrylamide contents of medium roasted espressos (30 mL) were 1.16 ± 0.25 and 2.31 ± 0.43 μg for pure arabica and robusta samples, respectively. Espressos prepared from commercial blends contained an average acrylamide level of 1.26 ± 0.28 μg. A 25% decrease was observed when comparing espressos prepared with medium and dark roasted coffee. The extraction efficacy of acrylamide for standard espressos of 30 mL was near 80%, being only affected by brew volume, with long espressos (70 mL) containing practically all acrylamide of the coffee cake (99%), almost double that of short ones (20 mL). When compared with other common coffee beverages, espresso acrylamide concentration (μg/L) was higher. However, due to the small volume per cup, it may contribute less to acrylamide ingestion.     

Uncertainty estimation and in-house method validation of HPLC analysis of carotenoids for food composition data production

The method for separation and quantitative determination of the main carotenoids in food by high-performance liquid chromatography (HPLC) was in-house validated. Tomato (Lycopersicon esculentum M.) as food matrix was used to demonstrate its linearity, repeatability, intermediate precision, detection and quantification limits, sensitivity and bias. In addition, stability of carotenoids was studied in function of temperature and time. Method accuracy was quantified through measurement uncertainties estimate based on this validation study. Furthermore, a study was conducted to evaluate variability coming from location in an experimental field composed by 12 subfields. The use of two metal free reverse phase columns and an organic mobile phase based on acetonitrile, methanol and dichloromethane enabled the separation of the six target compounds (trans-α-carotene, trans-β-carotene, β-cryptoxanthin, all-lycopene, lutein, zeaxanthin) within a 30 min run; detection at 450 nm and external calibration allowed the quantification of the analytes. Carotenoids concentration and measurement uncertainty, in mg/100 g, in tomato varieties “lido” and “for salad” were, respectively, 1.0 ± 0.14 and 0.39 ± 0.056 for trans-β-carotene, 8 ± 2.0 and 2.3 ± 0.57 for all-lycopene and 0.10 ± 0.017 and 0.08 ± 0.015 for lutein; trans-α-carotene, β-cryptoxanthin and zeaxanthin were not detected in both varieties (detection limits, in μg/100 g, 0.81, 0.57 and 0.77, respectively). For β-carotene and lutein, uncertainty associated with the entire process including small-scale within-region variation was statistically different, at a significance level of 5%, from measurement uncertainty (which includes sampling in the laboratory).     

High performance liquid chromatography method for the simultaneous determination of α-, γ- and δ-tocopherol in vegetable oils in presence of hexadecyltrimethylammonium bromide/n-propanol in mobile phase

A rapid methodology by RP-HPLC, 10 min of total analysis time, for the analysis of α-, γ- and δ-tocopherol in vegetable oils, in presence of retinol, retinyl acetate and α-tocopherol acetate was developed. Hexadecyltrimethylammonium bromide 0.1 M/n-propanol 65% (v/v) are used as mobile phase. Tocopherols were detected using UV and fluorescence detection. The quantification limits for α-, γ- and δ-tocopherols were 0.28, 0.12 and 0.23 mg L⁻¹, respectively. The method yielded satisfactory results when it was applied to vegetable oils and thus, it is suitable for their quality control.     

Antioxidant activity of Spirulina platensis extracts by supercritical carbon dioxide extraction

Supercritical CO₂ extraction of antioxidants from Spirulina platensis was optimized using response surface methodology. About 10.26 g/kg of extracts from S. platensis could be obtained under the optimum conditions of 48 °C at 20 MPa over a 4 h period. The antioxidant activity of the extracts prepared under the optimized condition, determined by linoleic acid peroxidation inhibition method, was lower compared with BHT and Trolox, but significantly higher than α-tocopherol in 300 min and became similar to α-tocopherol after that. The components of the extracts were further analyzed, and the results showed that the extracts contained 85.1 g/kg of flavonoids, 77.8 g/kg of β-carotene, 113.2 g/kg of vitamin A and 3.4 g/kg of α-tocopherol, which may contribute greatly to their high antioxidant activity. The main fatty acids in the extracts were palmitic acid (35.32%), linolenic acid (21.66%) and linoleic acid (20.58%).     

Antioxidant behaviour of carotenoids highly accumulated in HepG2 cells

The antioxidant behaviour of major dietary carotenoids accumulated at high concentrations in human hepatoma HepG2 cells was evaluated, in comparison with α-tocopherol. The cells that accumulated carotenoids and α-tocopherol at levels higher than the values reported in the human liver were exposed to mild oxidative stress with tert-butylhydroperoxide. β-Carotene (>2.6 nmol/mg protein) and astaxanthin (>1.8 nmol/mg protein) significantly suppressed lipid peroxidation, while β-cryptoxanthin and lutein did not. α-Tocopherol remarkably suppressed lipid peroxidation with an IC₅₀ value of 0.16 nmol/mg protein. Neither α-tocopherol nor any of the carotenoids except for lycopene showed pro-oxidant action even at high cellular concentrations. The antioxidant behaviours of carotenoids in a cellular milieu were quite different from those previously found in liposomes and homogeneous solutions. Further studies are required to assess the implications of the antioxidant behaviours found in the cultured cells on human health.     

Antioxidant activity of tomato lipophilic extracts and interactions between carotenoids and α-tocopherol in synthetic mixtures

In the present study we assayed the antioxidant activity of lipophilic extracts obtained from different tomato varieties. The results showed that cherry tomatoes, characterized by a high carotenoid content, had the highest antioxidant activity. A quantitative analysis of lycopene, β-carotene, lutein and α-tocopherol was also performed and the correlation between the antioxidant content and the antioxidant activity was estimated. The highest correlation coefficient was found for lycopene (R² = 0.9236, P ≤ 0.001). The analysis of two-component mixtures containing α-tocopherol and carotenoids showed that significant synergism occurred for all the combinations which contained α-tocopherol and β-carotene mixed together. The highest synergistic effects were detected for α-tocopherol-lycopene mixtures, which were the most efficient combinations tested in the present study. The analysis of the carotenoid combinations indicated that synergism occurred for lycopene-β-carotene, lycopene-lutein and lutein-β-carotene mixtures. The analysis of four-component mixtures did not show statistically significant synergistic effects.     

Purification,characterisation, and quantification of the soy allergen profilin (Gly m 3) in soy products

Profilins are pan-allergen proteins present in various plant foods and pollens. The objective was to develop a method for purification and characterisation of profilin from soy protein isolate. Furthermore, profilin was quantified in soy products and the effect of processing evaluated. Profilin was purified using poly-l-proline affinity chromatography, dialysis and ultrafiltration, and its quantification was implemented by indirect ELISA. Profilin in soymilks ranged from 4.37 ± 0.14 to 7.24 ± 0.30 mg/g protein, while in fermented products profilin ranged from 1.67 ± 0.02 to 5.47 ± 0.02 mg/g protein. Pasteurisation of soymilk was an ineffective method to completely eliminate profilin. Food matrix influenced thermal stability; at 100 °C, β-sheet and random coil structures were altered, while the α-helices remained intact. Induced fermentation of soybean meal by Bifidobacterium lactic, Lactobacillus plantarum and Saccharomyces cerevisiae resulted in 68.3% to 72.7% reduction of soy profilin. Heat treatment, fermentation and hydrolysis effectively reduced soy profilin.     

Antioxidative activity of Rosmarinus officinalis L. essential oil compared to its main components

This study was designed to examine the in vitro antioxidant activities of Rosmarinus officinalis L. essential oil compared to three of its main components (1,8-cineole, α-pinene, β-pinene). GC–MS analysis of the essential oil resulted in the identification of 19 compounds, representing 97.97% of the oil, the major constituents of the oil were described as 1,8-cineole (27.23%), α-pinene (19.43%), camphor (14.26%), camphene (11.52%) and β-pinene (6.71%). The oil and the components were subjected to screening for their possible antioxidant activity by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and β-carotene bleaching test. In the DPPH test system, free radical-scavenging activity of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were determined to be 62.45% ± 3.42%, 42.7% ± 2.5%, 45.61% ± 4.23% and 46.21% ± 2.24% (v/v), respectively. In the β-carotene bleaching test system, we tested series concentration of samples to show the antioxidant activities of the oil and its main components, whereas the concentrations providing 50% inhibition (IC₅₀) values of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were 2.04% ± 0.42%, 4.05% ± 0.65%, 2.28% ± 0.23% and 2.56% ± 0.16% (v/v), respectively. In general, R. officinalis L. essential oil showed greater activity than its components in both systems, and the antioxidant activities of all the tested samples were mostly related to their concentrations. Antioxidant activities of the synthetic antioxidant, ascorbic acid and BHT, were also determined in parallel experiments as positive control.     

Development of a highly sensitive and specific monoclonal antibody-based enzyme-linked immunosorbent assay for determination of doxycycline in chicken muscle,liver and egg

A modified indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) method was developed using a highly sensitive and specific monoclonal antibody (McAb) to determine doxycycline (DC) residues in chicken tissues and egg. The McAb against DC was produced by hybridoma technique and a modified ic-ELISA was characterised in terms of sensitivity, specificity, precision and accuracy. At optimal experimental conditions, the standard curve was constructed at concentrations ranged from 0.01 to 100 ng/ml. The IC₅₀ value was 1.32 ± 0.18 ng/ml. The limit of detection was 0.14 ± 0.02 ng/g. The recoveries of DC from spiked chicken liver, muscle, and egg at levels of 50–600 ng/g were 84.6–85.5%, 88.2–89.1%, and 84.4–89.3%, respectively. The coefficient variations (CVs) were 5.1–9.3%, 3.7–11.3%, and 4.7–9.8%, respectively. Linear regression analysis showed good correlation, with r² values 0.9909 for chicken liver and 0.9916 for chicken muscle.