Heat-assisted slurry sampling GFAAS method for determination of lead in food standard reference materials

A valid method based on heat-assisted slurry sampling graphic furnace atomic absorption spectrometry (HASS-GFAAS) was developed for the accurate determination of trace Pb in food standard reference materials (SRMs). The HASS technique significantly improved Pb recovery and precision compared to conventional slurry sampling techniques. The optimized HASS procedure was performed as follows: first, the sample (particle size ≤ 150 μm) was diluted with 0.05% (v/v) Triton X-100 containing 2% HNO₃ and 1% H₂O₂ followed by heating for 20 min at 120 °C on a heating block. Next, the obtained slurry was sonicated in an autosampler cup, and finally, the slurry was introduced into a graphite tube and analyzed by the GFAAS with a Pb electrodeless discharge lamp (EDL). Calibration with aqueous standard solutions was used for Pb determination in food samples. The characteristic mass and limit of detection for Pb based on the integrated absorbance for a 2% (m/v) sample were 12 ± 0.6 pg and 0.003 mg kg⁻¹, respectively. The accuracy (95.1–102% recovery) and good precision (0.1–3.6%) of this procedure are illustrated by the results obtained for the 12 food reference materials. The proposed method is suitable for determination of trace Pb in solid food samples.     

Synthesis and characterization of functionalized silica with 3,6-ditia-1,8-octanediol for the preconcentration and determination of lead in milk employing multicommuted flow system coupled to FAAS

Novel functionalized silica, containing 3,6-dithia-1,8-octanediol (Si-DIO), was synthesized and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and nuclear magnetic resonance (NMR) of ¹³C and ²⁹Si. The Si-DIO was used to pre-concentrate and determine the amount of Pb(II) in milk samples employing a multicommuted flow system coupled to flame atomic absorption spectrometry (FAAS). For the adsorption process, a pre-concentration minicolumn with 100 mg of Si-DIO, a solution of 0.005 mg L⁻¹ Pb(II) at pH 9.0 and HNO₃ as the eluent was used, obtaining an enrichment factor of 28 times with retention efficiency higher than 99%. The Pb(II) ion, using the multicommuted flow system coupled to FAAS, showed a linear response between 0.005 and 20.0 mg L⁻¹; a linear coefficient where r = 0.9939 and n = 7; a detection limit estimated at 0.001 mg L⁻¹ and a relative standard deviation of 3.8% (n = 50). Fifty pre-concentrations runs were tested in the minicolumn without significant variation in the analytical signal. The proposal system showed analytical applicability to determine Pb(II) ion in milk samples, presenting recovery of 90.7–102.5%.     

Single-run analysis of vitamin D photoproducts in oyster mushroom (Pleurotus ostreatus) after UV-B treatment

A single-run high performance liquid chromatography (HPLC) with diode array detector (DAD) based method was developed for the separation, identification and comprehensive quantification of degradation products of ergosterol formed in oyster mushroom (Pleurotus ostreatus) after UV-B exposure. After 60 min, 10 substances involved in the photoprocess were separated, identified by their characteristic DAD spectrum and distinguished by their molecular weight, in cases where spectra were identical: vitamin D₂, previtamin D₂, tachysterol₂, lumisterol₂ and ergosterol, and, in minor quantity, their structural analogues of the 22,23-dihydroergocalciferol (vitamin D₄) series. Sample preparation protocol affected the total yields and the ratios of previtamin and vitamin D₂/D₄. Hot alkaline hydrolysis resulted in the best digestion of the mushroom matrix and accordingly gave the highest vitamin D yield (D₂: 141.32 μg g⁻¹ dry matter, DM; D₄: 22.72 μg g⁻¹ DM). Limit of detection for vitamin D_2/4 was 0.02 μg g⁻¹ dry matter (DM) and was estimated for previtamin D_2/4 (0.06 μg g⁻¹ DM), tachysterol_2/4 (0.02 μg g⁻¹ DM) and lumisterol_2/4 (0.06 μg g⁻¹ DM). Recovery of spiked vitamin D₂ was 97 ± 0.7%. The study provides an analytical tool to assess the process of vitamin D generation after UV-B treatment for the production of oyster mushrooms with a balanced nutritional profile of vitamin D compounds.     

Development of a new method for determination of aluminum (Al) in Jordanian foods and drinks: Solid phase extraction and adsorption of Al3+-d-mannitol on carbon nanotubes

In this work, a new method was developed for determination of aluminum (Al) in traditional Jordanian foods (Mansaf, Kofta, Tabboola, Hummous, bread), tea, Arabian coffee and water samples. The method involved solid phase extraction (SPE) of Al³⁺ from the digested samples after complexation with d-mannitol using carbon nanotubes (CNT) as the extractive sorbent. Formation of the Al³⁺-d-mannitol complex was confirmed by infrared spectroscopy. Optimization of the SPE method involved sample pH, d-mannitol-to-Al mole ratio, sample loading and elution flow rates, adsorbent mass, eluent concentration and volume. Based on spiked water samples, the characteristics of the method were as follows: the limit of quantification: 23 μg l⁻¹; sensitivity: 0.0036 (mg l⁻¹)⁻¹; %RSD range: 0.4–1.9%; recovery range: 76.0–93.0%. The equilibrium, thermodynamic and kinetic adsorption studies of Al³⁺-d-mannitol on CNT revealed that adsorption was spontaneous, exothermic, preferred, of physical nature; followed second-order rate kinetics; pore diffusion was not the only rate-controlling step; both Langmuir and Freundlich isotherms represented the data satisfactorily.     

Essential and non-essential elements in Brazilian infant food and other rice-based products frequently consumed by children and celiac population

Rice and its derivatives are important source of essential and non-essential elements. Essential elements as cobalt (Co) and selenium (Se) are vital for human homeostasis. However, non-essential elements such as arsenic (As), cadmium (Cd) and lead (Pb) may be present in rice-based food and consequently, people can be exposed—especially children and the celiac population. This study aimed to determine essentials and non-essentials elements in rice-based products and baby food and also to evaluate nutritional risk by estimating the daily intake of non-essential elements. Regarding essential elements, Co and Se presented the highest concentrations in rice flour (56 μg kg⁻¹) and porridge (254 μg kg⁻¹), respectively. For non-essential elements, the highest concentrations of As, Cd and Pb were 104 μg kg⁻¹ (porridge), 16 μg kg⁻¹ (flour), and 188 μg kg⁻¹ (bread), respectively. Total As concentration in Brazilian rice-based baby food was <29 μg kg⁻¹. However, As-speciation revealed inorganic-As (i-As) as the main specie. The highest estimated daily intake of Cd, Pb and i-As were 1.37 (rice-based baby food); 10.39 (pasta); and 3.34 (pasta) μg d⁻¹, respectively. Therefore, continuous food monitoring for nutritional and toxicological purpose is necessary, especially concerning these particular populations and discussions for maximum levels of non-essential elements.     

A fast and effective method of quantitative analysis of VB1, VB2 and VB6 in B-vitamins complex tablets based on three-dimensional fluorescence spectra

Scattering signals and partial overlapping of target peaks usually appear in fluorescence determination. In this study, the improved wavelet moment method was proposed and applied to the quantitative determination of multiple target components in real B-vitamins complex tablets based on three-dimensional (3D) fluorescence spectra. The correlation coefficients (R) were more than 0.9939, and the correlation coefficients of leave-one-out cross-validation (R_LOO-cv) were more than 0.9376. The inter-day and intra-day variations were less than 5.8% and 6.1%, respectively. The recovery ranged from 97.6% to 109.4%. The limits of detection (LODs) and quantification (LOQs) were less than 0.07 μg mL⁻¹ and 0.13 μg mL⁻¹, respectively. All the statistical parameters indicated that the method was stable and reliable. The application to the practical samples confirmed that wavelet moment method effectively extracted the features of target components in 3D spectra and the proposed method could be applied to the analyses of food or other complex samples.     

Direct atomic absorption spectrometry determination of arsenic,cadmium, copper,manganese, lead and zinc in vegetable oil and fat samples with graphite filter furnace atomizer

The article presents the results of optimization of operation parameters, investigation of analytical characteristics and the abilities of a graphite filter-furnace (FF) atomizer for the direct electrothermal atomic absorption spectroscopy (ET AAS) determination of trace amounts of Mn, As, Pb, Cu, Cd and Zn in some vegetable oils and fats. The effect of pyrolysis and atomization temperatures of the graphite FF atomizer on atomic absorbance values of the listed elements at their evaporation from some organic solutions in the presence of a Pd-Mg chemical modifier (CM) was investigated. For the ET AAS determination of As, Pb, Cd and Zn with Pd-Mg CM, the temperature of the graphite FF atomizer for the pyrolysis step can be raised by 250–350 °C. This mode allows to eliminate the background absorption, to increase the sensitivity of the elements to be analyzed and to enhance the total content of vegetable oils or fats in organic solutions up to 0.5 g mL⁻¹. The obtained limits of quantification for Mn, As, Pb, Cu, Cd and Zn were 0.002, 0.004, 0.004, 0.002, 0.0008, 0.0004 mg kg⁻¹, respectively. The relative standard deviation (RSD) varied between ∼3 and 8% and the time of one element determination did not exceed ∼3–5 min. The reliability of the proposed method was checked using the reference method. A paired Student's t-test showed no significant difference between the results obtained by both methods on a 95% confidence level.     

Geographical discrimination of Italian honey by multi-element analysis with a chemometric approach

In this study the concentrations of K, Ca, Mg, Na, Al, Zn, Fe, Mn, Cu, Cr, Ni, Se, Pb, Cd, and As in 39 honey samples of different botanical (orange-blossom, lemon-blossom, chestnut, eucalyptus, acacia, sulla and wildflower honeys) and geographical (Sicily and Calabria, Italy) origin were determined by ICP-OES and ICP-MS. The most abundant minerals decreased in the following order: K (mean value: 1.57 mg g⁻¹) > Ca (0.2 mg g⁻¹) > Mg (0.121 mg g⁻¹) > Na (0.092 mg g⁻¹). Recommended Dietary Allowance (RDA) values and benchmark levels were employed to assess the honey quality and safety. The data excluded toxicological risks: for an adult of 60 kg, a daily intake of 2 g of honey covered maximum 0.40% of Tolerable Weekly Intake (TWI) for Al, 0.33% of Benchmark Dose of 1% Extra Risk (BMDL01) for Pb, and 0.07% of Tolerable Daily Intake (TDI) for Ni. Mineral content marks the differences in honey samples from different geographical origin despite the botanical factor weight and can be used as a tool to assess the traceability of honeys. The discrimination between Sicilian and Calabrian honeys was achieved by Principal Component Analysis (PCA), and also the results of Canonical Discriminant Analysis (CDA) indicate that the 100% of total samples are correctly classified. This research contributes to the studies to determine the geographical origin of honeys.     

Exposure assessment of arsenic speciation in different rice types depending on the cooking mode

Total (As_t), inorganic arsenic (As_i = As(III) + As(V)) and dimethylarsonic acid (DMA) were determined in 37 commercial rice samples collected in France. As_t was measured by inductively coupled plasma-mass spectrometry (ICP-MS) whereas anion-exchange chromatography – ICP-MS was used for As_i and DMA determination. As_t in raw rice varied from 0.041 to 0.535 mg kg⁻¹ whereas As_i varied from 0.025 mg kg⁻¹ (polished Basmati rice) up to 0.471 mg kg⁻¹ (organic rice duo). The daily intake and associated health risk for different population groups as a function of age and gender was also assessed. The intake varied between 0.002 and 0.184 μg kg⁻¹ body weight for As_t and 0.002 and 0.153 μg kg⁻¹ body weight for As_i, which do not pose a chronic toxicity risk. Organic wholegrain rice may entail a risk for children in the case of sole consumption at the expense of polished rice. The impact of rice cooking/boiling in terms of the overall toxicological risk related to As species was also investigated. Pre-rinsing and boiling the raw rice by using an excess of water is the most efficient mode to obtain a significant As_i removal and further reduction of the toxicological risk for children, particularly for white rice varieties.     

Spectrophotometric method for determination of aluminium content in water and beverage samples employing flow-batch sequential injection system

A sensitive, precise and reliable flow-batch method for the determination of aluminium (Al) was developed using a sequential injection-monosegmented flow system incorporating a mixing chamber unit. Eriochrome cyanine R (ECR) was used as a chromogenic reagent in the presence of N,N-dodecyltrimethylammonium bromide (DTAB). The Al-ECR complex at pH 6 gave a maximum absorption at 584 nm. In-line single standard calibration and a standard addition procedure were developed employing the monosegmented flow technique. Under the optimum conditions, a linear calibration graph in the range of 0.0075–0.625 mg L⁻¹ Al was obtained with limits of detection and quantitation of 0.0020 and 0.0070 mg L⁻¹, respectively. Relative standard deviations were 0.8 and 1.3% for 0.010 and 0.025 mg L⁻¹ Al (n = 11), respectively. A sample throughput of 24 h⁻¹ using an in-line standard calibration approach and 6 h⁻¹ using four standard addition levels was achieved. The developed system was successfully applied to water samples and beverage samples. The results agreed well with those obtained from the ICP-AES method. Good recoveries between 85 and 104% were obtained.     

Genetic diversity of nutritionally important carotenoids in 94 pea and 121 chickpea accessions

Biofortification of staple crops via breeding is an attractive strategy for reducing human micronutrient deficiencies. The objective of this research was to examine the concentration of carotenoids in diverse pea and chickpea accessions grown in Saskatchewan (Canada) using high performance liquid chromatography. In pea accessions mean concentration of lutein was highest (11.2 μg g⁻¹) followed by β-carotene (0.5 μg g⁻¹), zeaxanthin (0.3 μg g⁻¹), and violaxanthin (0.3 μg g⁻¹). Green cotyledon pea accessions were richer in β-carotene and total carotenoids compared to yellow cotyledon accessions. In chickpea accessions mean concentration of lutein (8.2 μg g⁻¹) was highest followed by zeaxanthin (6.2 μg g⁻¹), β-carotene (0.5 μg g⁻¹), β-cryptoxanthin (0.1 μg g⁻¹), and violaxanthin (0.1 μg g⁻¹). Desi chickpea accessions had higher carotenoid concentration than kabuli accessions. This research identified pea and chickpea accessions that can be utilized in breeding for the improvement of carotenoid concentration through biofortification.     

Determination of clothianidin in food products by using an automated system with photochemically induced fluorescence detection

A flow-through system based on the integration of solid-phase spectroscopic detection implemented with photochemically induced fluorescence (PIF) is proposed for the determination of clothianidin (a non-fluorescent neonicotinoid insecticide) through a multicommutated method. The pesticide is injected into the carrier stream (0.015 mol L⁻¹C₂H₄O₂/NaC₂H₃O₂, pH = 5.0) and flows towards a homemade photoreactor, which consists of a PTFE tubing loosely coiled around a low-pressure mercury lamp (15W). After the photochemical reaction of clothianidin, the generated fluorescent photoproduct is transported to a flow cell packed with Sephadex-SP C-25 where it is retained and monitored (λ_ex = 357 nm/λ_em = 418 nm). The method presents a detection limit of 1.5 ng mL⁻¹, a sample throughput of 23 h⁻¹ and inter-day relative standard deviation lower than 3%. The described system has been satisfactorily applied to the determination of clothianidin in samples of drinking water, rice and honey. Taking into account that the maximum residue limit specified in the Codex Alimentarius Commission for rice grains is 0.5 mg kg⁻¹, recovery experiments have been carried out for clothianidin concentrations in the 0.3-10.0 mg kg⁻¹ range.     

Major and trace elements levels in multifloral and unifloral honeys in Croatia

Different honey types were collected in Croatia during 2010 and 2011: 7 multifloral orchard honeys, 7 multifloral meadow honeys, 19 black locust, 9 chestnut, 11 lime and 6 sage honeys. Elements were measured using graphite (As, Cu, Cd, Pb, Se) and flame atomic absorption spectrometer (Ca, Fe, K, Mg, Na, Zn) and by mercury analyser (Hg). Significant differences in Ca, Fe, K, Mg, Zn, As and Hg levels were observed between honey types. In chestnut honey were determined (K, Ca, Mg: mg kg⁻¹; Hg, Ad, Cd: μg kg⁻¹): the highest concentrations of K 2824.4, Ca 486.7, Mg 59.1 and Hg 2.52; the lowest of As 24.1 and Cd 2.52. Lime honey has been shown the highest content of Cu (20.6 mg kg⁻¹), Zn (6.78 mg kg⁻¹), Cd (2.14 μg kg⁻¹) and Pb (810.3 μg kg⁻¹). The lowest levels of following elements were determined in black locust honey (Fe, K, Mg: mg kg⁻¹; Hg: μg kg⁻¹): Fe 2.77, K 304.7, Mg 8.02 and Hg 0.82. Sage honey had the lowest Ca and Na content (173.9 and 31.8 mg kg⁻¹). Among the multifloral honeys, the following was determined (Fe, Na, Cu: mg kg⁻¹; As, Pb: μg kg⁻¹): orchard honey – highest of Fe 5.17 and As 276.1, lowest Pb 301; meadow honey – highest Na 36.1, lowest Cu 4.38. The average Ca, Cu and Pb levels found in multifloral honey types were much higher than those reported in other European countries. Calcium levels in lime, chestnut and black locust were higher than those from other countries.     

Comparison of the chemical composition of British and Continental European bottled waters by multivariate analysis

The elemental composition of 37 bottled waters from the UK and continental Europe has been determined. Ca, K, Mg, Na, Al, As, Ba, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Sr, U, V and Zn were determined by ICP-OES and ICP-MS, in addition to inorganic and total organic carbon. The composition of all the waters analysed fell within the guideline values recommended by the World Health Organization. Na, Ca, Sr and Ba showed the widest variation in concentrations, ranging over two orders of magnitude. Levels of Fe were below the limit of detection (30 μg L⁻¹) in all samples analysed. Waters produced in the UK generally showed lower levels of most major elements and trace metals, with the exception of Ba (up to 455 μg L⁻¹). Italian waters showed the highest concentrations of Sr (3000–8000 μg L⁻¹) and U (8–13 μg L⁻¹), whereas waters produced in Slovakia and the Czech Republic showed the highest levels of Pb (0.7–4 μg L⁻¹). The use of multivariate analysis reveals an association between high alkaline metal content and high concentrations of As and Cr. There also appears to be a correlation between high Ca and Sr content and high levels of U. Analysis of variance (ANOVA) indicates that the composition of bottled water can be distinguished primarily by the country of origin, over other factors including the geological environment of the source. This would suggest that composition reflects, and is biased towards, consumer preferences.     

Voltammetric determination of vitamin B6 in food samples and dietary supplements

A simple and rapid voltammetric method based on the use of disposable screen-printed electrodes is proposed for the determination of vitamin B₆. The influence of the pH on the voltammetric response was analyzed. Estimation of the linear range (2.0 × 10⁻⁶/7.2 × 10⁻⁵ M), calibration function, limit of detection (1.5 × 10⁻⁶ M) and reproducibility was performed along with the determination of possible interferences from species present in real samples. The proposed analytical system was successfully applied for the determination of pyridoxine in multivitamin supplements, energy drinks and breakfast cereals by using the standard addition method.     

Optimization of cheese sample preparation methodology for free amino acid analysis by capillary isotachophoresis

The objective of this work was the evaluation of different conditions for the selected free amino acids extraction from cheese samples, followed by capillary isotachophoresis analysis. Parameters of the extraction: concentration and type of extraction reagents (solvents: methanol, ethanol and mineral acids: perchloric acid, trichloroacetic acid, sulphuric acid and hydrochloric acid), time and temperature, and isotachophoretic separation conditions (voltage, time) were studied. Repeatability, reproducibility and stability of this method at different conditions are discussed. The best yield of free amino acids was obtained after triple extraction (30 min each process) with 0.1 M hydrochloric acid at 50 °C. Histidine, lysine, arginine, ornithine, tyrosine, and phenylalanine were determined using calibration curves and the standard additions method in different types of cheeses. The highest level of amino acids was determined in semi-hard cheese (2626.3 mg 100 g⁻¹ – calibration curve, and 2679.2 mg 100 g⁻¹ – standard additions method), whereas the lowest were found in sheep cheese (426.3 mg 100 g⁻¹ and 455.7 mg 100 g⁻¹, respectively), and Gouda type cheese samples (441.5 mg 100 g⁻¹ and 472.8 mg 100 g⁻¹, respectively).     

Fast method for the determination of copper,manganese and iron in seafood samples

A slurry sampling flame atomic absorption spectrometric method is proposed for the determination of copper, manganese and iron in oysters (Crassostrea rhizophora), clams (Anomalocardia brasiliana) and mussels (Mytella guiyanensis; Perna perna). Optimization was carried out using univariate methodology involving the following variables: nature and concentration of the acid solution for slurry preparation, sonication time and sample mass. The optimized conditions were 80 mg of sample ground in a cryogenic mil, dilution using 1.0 mol L⁻¹ nitric /hydrochloric acid solution, sonication time of 30 min and a slurry volume of 10 mL. The calibration curves had been prepared using standards of copper, manganese and iron also in 1.0 mol L⁻¹ nitric/hydrochloric acid solution. This method allowed the determination of copper, manganese and iron by FAAS, with detection limits of 0.17, 0.09 and 0.46 μg g⁻¹, respectively. The precision, expressed as relative standard deviation (RSD), are 3.0%, 2.9% and 3.8% (n=10), for concentrations of copper, manganese and iron of 17, 22 and 719 μg g⁻¹, respectively. The accuracy of the method was confirmed by analysis of the certified oyster tissue (NIST 1566b). The proposed method was applied for the determination of copper, manganese and iron in samples of oyster, clams and mussels, collected in Ubatuba and Todos os Santos Bay, Brazil. The obtained concentrations varied between 17.1 and 143.9 μg g⁻¹, 17.9 and 29.7 μg g⁻¹ and 364 and 1388 μg g⁻¹, respectively, for copper, manganese and iron. These values agree well with other data reported in the literature. The results showed no significant differences (P>0.005) using the proposed method with those obtained after complete digestion and determination by inductively coupled plasma-optical emission spectroscopy (ICP-OES).     

A rapid and sensitive method for the determination of dibutyl phthalate in wine by flow-injection chemiluminescence analysis

A sensitive method for the determination of picogram level dibutyl phthalate (DBP) in wine by flow-injection chemiluminescence (FI–CL) analysis is presented for the first time, which was based on the quenching effect of DBP on the luminol–myoglobin (Mb) CL system. The decrement of CL intensity was linearly proportional to the logarithm of DBP concentration in the range of 0.1–100 pg mL⁻¹ with the detection limit of 0.03 pg mL⁻¹ (3σ). At a flow rate of 2.0 mL min⁻¹, a complete determination of DBP including sampling and washing could be accomplished in 0.5 min, giving the maximum sample throughput of 120 h⁻¹. The proposed method was successfully applied to the determination of DBP in wine, human serum and urine samples with the relative standard deviations (RSDs) of less than 3.0% (n = 5). The molecule docking results showed that DBP interacted with the amino acid residues near the heme moiety of Mb. The possible CL mechanism of luminol–Mb–DBP reaction should be that the binding of Mb with DBP forming a 1:1 complex (binding constant K = 1.55 × 10⁴ L mol⁻¹) led to the conformational change of Mb and resulted in the quenching of CL intensity.     

An efficient,rapid and microwave-accelerated dispersive liquid–liquid microextraction method for extraction and pre-concentration of some organophosphorus pesticide residues from aqueous samples

In this paper, microwave-accelerated dispersive liquid–liquid microextraction has been developed for the extraction/preconcentration of some organophosphorus pesticides from aqueous samples prior to their analysis by gas chromatography–flame ionization detection. In this method, temperature of a high volume of aqueous sample is elevated by a microwave oven and then a mixture of extraction and disperser solvents is rapidly injected into the aqueous phase. After cooling to room temperature, the phase separation is accelerated by centrifuging. The main experimental factors affecting performance of the method including type and volume of the extraction and disperser solvents, temperature, pH, and salt addition were investigated and optimized. Under the optimum extraction conditions, the method resulted in low limits of detection and quantification within the ranges of 0.65–1.3 and 2.2–4.5 μg L⁻¹, respectively. Relative standard deviations were in the range of 2–7% (C = 40 or 100 μg L⁻¹) for intra-day (n = 6) and inter-day (n = 4) precisions. Finally, the proposed method was successfully applied to analysis of the target analytes in surface water and well water and fruit juice samples; diazinon was determined at μg L⁻¹ level in apple juice.     

Proximate composition and lipid profile of red mullet (Mullus barbatus) from two sites of the Tyrrhenian and Adriatic seas (Italy): a seasonal differentiation

Proximate composition, unsaponifiable lipid components (cholesterol, squalene, tocopherols, all-trans retinol, total carotenoids) and fatty acid profile were evaluated on red mullet (Mullus barbatus) caught in the Central Tyrrhenian and Central Adriatic seas (Italy). The study was conducted in spring, the reproduction period, and in autumn, the period of maximum recruitment and market demand for this species. Results showed that, in fish from both sites, protein (18.1–18.8 g 100 g⁻¹), nonprotein nitrogen (0.32–0.35 g 100 g⁻¹), ash (1.27–1.42 g 100 g⁻¹) and cholesterol (56.8–73.7 mg 100 g⁻¹) contents were almost stable. Total lipid levels were highly variable, with very low levels in spring (0.96–1.48 g 100 g⁻¹) and high levels in autumn (7.28–8.72 g 100 g⁻¹). On a total fatty acids basis, polyunsaturated fatty acids (PUFA) were significantly higher in spring (30–40% of total fatty acids), when fish was lean, than in autumn (20%), while monounsaturated fatty acids were significantly higher in autumn (35–38%) than in spring (18–29%). Saturated fatty acids were almost stable throughout the year (34–39% of total fatty acids). Red mullet from the two sites showed a good nutritional value; in particular they proved to be a good source of n-3 PUFA, which accounted for 75–80% of total PUFA, regardless of the fishing season. However, it was in autumn that red mullet exhibited the highest content of n-3 PUFA (>1000 mg 100 g⁻¹ wet fillet). The comparison of samples by geographical origin showed no difference in autumn, while slight differences were observed in spring.