Composition of fatty acids, tocopherols, tocotrienols and ß-carotene content in oils of seeds of Brazilian Sapindaceae and Meliaceae species.

This study analyzes the lipid composition and the oxidative stability of oils of Sapindaceae and Meliaceae seeds. The oil content ranged from 14.7% (Guarea guidonia) to 30.1% (Allophylus puberulus and Paullinia elegans). Ten fatty acids were identified in seed oils. Guarea guidonia seeds accumulated mainly oleic (44.9%) and linoleic (24.1%) acid, whereas the unusual gondoic and paullinic acids were identified in A. puberulus (15.8%; 8.9%) and P. elegans (14.4%; 44.2%), respectively. The oil of P. elegans had the highest oxidative stability (16.2 h.). Tocopherol predominated in A. puberulus (10.4 mg/100 g) and tocotrienol predominated in G. guidonea and P. elegans (2.6 mg/100 g). The vitamers α-tocopherol, γ-tocopherol, and γ-tocotrienol were found in the studied oils. ß-carotene was predominantly detected in the oil of A. puberulus seeds (22.4 µg/g). Guarea guidonia seed oil has a high potential in food due to richness in essential fatty acids. In turn, A. puberulus and P. elegans oils could be suggested for other industrial purposes (e.g., biodiesel, varnishes, paints, soaps, or oleochemicals) due to their content of long-chain fatty acids.

Walnut allergens: molecular characterization, detection and clinical relevance.

Food-induced allergies have been regarded as an emergent problem of public health. Classified as important allergenic ingredients, the presence of walnut and other nuts as hidden allergens in processed foods constitutes a risk for sensitized individuals, being a real problem of allergen management. Attending to the increasing importance dedicated to walnut allergy, this review intends to provide the relevant and up-to-date information on main issues such as the prevalence of walnut allergy, the clinical threshold levels, the molecular characterization of walnut allergens and their clinical relevance, as well as the methodologies for walnut allergen detection in foods. As the walnut used in human diet comes from Juglans regia and Juglans nigra, the molecular characterization of the allergens from both species included in the prolamins (Jug r 1, Jug n 1 and Jug r 3), cupins (Jug r 2, Jug n 2 and Jug r 4) and profilins (Jug r 5), together with respective clinical relevance, were compiled in this review. The most recent progresses on walnut allergen detection techniques (protein- and DNA-based) are described and critically compared, including the emergent multitarget approaches.

Fat-soluble vitamin (A, D, E, and ß-carotene) contents from a Portuguese autochthonous cow breed--Minhota.

In Portugal, commercial milk is obtained almost entirely from cows of the Holstein breed. However, other breeds may also show dairy aptitude, and produce milk of good quality. The aim of this study was to investigate the effect of the breed factor in the vitamin contents of milks from Holstein and the autochthonous Portuguese breed Minhota, as well as possible variations due to season. Milk samples were collected from 15 cows of each breed. Milk from Minhota cows showed higher contents of retinol, retinyl palmitate, α-tocopherol, and ß-carotene. No differences were verified between breeds regarding vitamin D(3) content, but Holstein cows presented higher amounts of provitamin D(3). Seasonal variations were not observed for milk samples from Holsteins, and only a very small variation was observed for milk samples from Minhota cows, mainly in retinol, α-tocopherol, and provitamin D(3) levels. This study revealed that breed has a pronounced effect on milk fat-soluble vitamins, which is an important observation regarding future genetic selection plans. Also, the increased vitamin amounts found in milk from Minhota cows can be regarded as an important nutritional parameter that can potentiate the economical value of this breed.

Lipid content and fatty acid profile of Senegalese sole (Solea senegalensis Kaup, 1858) juveniles as affected by feed containing different amounts of plant protein sources.

A growth trial with Senegalese Sole (Solea senegalensis Kaup, 1858) juveniles fed with diets containing increasing replacement levels of fishmeal by mixtures of plant protein sources was conducted over 12 weeks. Total fat contents of muscle, liver, viscera, skin, fins and head tissues were determined, as well as fatty acid profiles of muscle and liver (GC-FID analysis). Liver was the preferential local for fat deposition (5.5-10.8% of fat) followed by fins (3.4-6.7% fat). Increasing levels of plant protein in the diets seems to be related to increased levels of total lipids in the liver. Sole muscle is lean (2.4-4.0% fat), with total lipids being similar among treatments. Liver fatty acid profile varied significantly among treatments. Plant protein diets induced increased levels of C16:1 and C18:2 n-6 and a decrease in ARA and EPA levels. Muscle fatty acid profile also evidenced increasing levels of C18:2 n-6, while ARA and DHA remained similar among treatments. Substitution of fishmeal by plant protein is hence possible without major differences on the lipid content and fatty acid profile of the main edible portion of the fish - the muscle.

Antioxidant potential of chestnut (Castanea sativa L.) and almond (Prunus dulcis L.) by-products.

The antioxidant properties of almond green husks (Cvs. Duro Italiano, Ferraduel, Ferranhês, Ferrastar and Orelha de Mula), chestnut skins and chestnut leaves (Cvs. Aveleira, Boa Ventura, Judia and Longal) were evaluated through several chemical and biochemical assays in order to provide a novel strategy to stimulate the application of waste products as new suppliers of useful bioactive compounds, namely antioxidants. All the assayed by-products revealed good antioxidant properties, with very low EC(50) values (lower than 380 µg/mL), particularly for lipid peroxidation inhibition (lower than 140 µg/mL). The total phenols and flavonoids contents were also determined. The correlation between these bioactive compounds and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, reducing power, inhibition of ß-carotene bleaching and inhibition of lipid peroxidation in pig brain tissue through formation of thiobarbituric acid reactive substances, was also obtained. Although, all the assayed by-products proved to have a high potential of application in new antioxidants formulations, chestnut skins and leaves demonstrated better results.

Fast low-pressure gas chromatography-mass spectrometry method for the determination of multiple pesticides in grapes, musts and wines.

A fast method using low-pressure gas chromatography coupled to mass spectrometry (LP-GC/MS) was implemented and optimized to yield a complete separation of 27 representative pesticides in grapes, musts and wines. Extraction was performed with acetonitrile, applying quick, easy, cheap, effective, rugged and safe (QuEChERS) methodology. Several LP-GC/MS conditions such as column temperature, injection conditions, flow rate, MS conditions and matrix effects were evaluated to achieve the fastest separation with the highest sensitivity in MS detection (selected ion monitoring mode). After optimization, all 27 pesticides were extracted, chromatographically separated and detected in less than 20 min. Acceptable recoveries for nearly all pesticides at three different spiking levels (from 0.04 to 2.5 microg/g) were achieved with good repeatability (from 3 to 21%). Limits of quantification (from 0.02 to 5 microg/g) were lower than the maximum limit of residues, when established for pesticides.

Lipid profile and quality indices of ostrich meat and giblets.

In this study, the lipid profile of 5 different edible tissues (leg, thigh, heart, gizzard, and liver) of ostrich was analyzed. Ostrich edible tissues presented a low fat content (<5 g/100 g wet basis). Gizzard and heart revealed the highest amounts of total cholesterol (1.77 and 1.47 mg/g wet basis, respectively), differing significantly from all other tissues (which averaged 0.95 mg/g wet basis). The main tocochromanol in all tissues was α-tocopherol (10.3 µg/g wet basis in heart and an average of 3.4 µg/g wet basis for all the remaining tissues). All the samples presented a fatty acid profile, dominated by polyunsaturated fatty acids (PUFA) (>38%), namely, linoleic and arachidonic acids. The leg presented simultaneously the highest PUFA/saturated fatty acids (SFA), the lowest n-6/n-3 ratios, and the most favorable lipid quality indices among all tissues in comparison.

The effect of the olive fruit fly (Bactrocera oleae) on quality parameters, and antioxidant and antibacterial activities of olive oil.

The present study was performed on olives from two Algerian cultivars (Limli and Rougette de Metidja) with different rates of attack by the Bactrocera oleae fly (0%, not attacked; 100%, all attacked; and real attacked %) and the corresponding olive oils. The aim was to verify the attack effect on quality parameters (free fatty acid, peroxide value, K232 and K270, oxidation stability), bioactive compounds (fatty acids and tocopherols, and total phenols and flavonoids), and on the antioxidant (reducing power, FRAP, ß-carotene bleaching inhibition, ABTS and DPPH) and antibacterial (against 8 referenced human enteropathogenic bacteria by the agar disc diffusion method) capacities. Oils from infested olives were downgraded to the virgin olive oil category. Rougette de Metidja, the cultivar with a higher drupe size, was more attacked than Limli. The B. oleae attack causes an important decrease in the total phenolic contents (>30%) but to a lesser degree in the case of tocopherols. Among them, α-tocopherol is the most affected. The antioxidant and antibacterial activities were highly correlated with phenolic levels. The results of this study show the importance of controlling the fly attack because it causes a decrease in the beneficial health effects of olive oils.

Isoflavones in food supplements: chemical profile, label accordance and permeability study in Caco-2 cells.

Consumers nowadays are playing an active role in their health-care. A special case is the increasing number of women, who are reluctant to use exogenous hormone therapy for the treatment of menopausal symptoms and are looking for complementary therapies. However, food supplements are not clearly regulated in Europe. The EFSA has only recently begun to address the issues of botanical safety and purity regulation, leading to a variability of content, standardization, dosage, and purity of available products. In this study, isoflavones (puerarin, daidzin, genistin, daidzein, glycitein, genistein, formononetin, prunetin, and biochanin A) from food supplements (n = 15) for menopausal symptoms relief are evaluated and compared with the labelled information. Only four supplements complied with the recommendations made by the EC on the tolerable thresholds. The intestinal bioavailability of these compounds was investigated using Caco-2 cells. The apparent permeability coefficients of the selected isoflavonoids across the Caco-2 cells were affected by the isoflavone concentration and product matrix.

Analysis of heterocyclic aromatic amines in foods by gas chromatography-mass spectrometry as their tert.-butyldimethylsilyl derivatives.

A derivatization method for the analysis of 12 heterocyclic aromatic amines (HAs) in food, by gas chromatography-electron impact mass spectrometry, was developed. The amines are derivatized in a one-step reaction with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide. The derivatives are characterized by easy-to-interpret mass spectra due to the prominent ion [M-57]+ by loss of a tert.-butyldimethylsilyl group, allowing quantification in the selected-ion monitoring mode at the picogram level. The effect of temperature, time, and reagents on the formation of the derivatives was monitored in detail. Quality parameters were evaluated in the optimum working conditions. This derivatization method is not applicable to the pyridoimidazoles Glu-P-1 and Glu-P-2 and to the beta-carboline harman due to incompletely derivatization. The instability of the imidazolquinoline and imidazoquinoxaline derivatives, requiring their injection on the same working day, is a further drawback. This simple, rapid and accurate derivatization procedure is suitable for routine analysis, as illustrated by the analysis of some common foods.

Gas chromatographic-mass spectrometric quantification of 4-(5-)methylimidazole in roasted coffee after ion-pair extraction.

A GC-MS method is described for quantification of 4-(5-)methylimidazole (4MI) in coffee. Although tested, GC-flame ionization detection proved inadequate for this purpose due to the complexity of the coffee matrix. The developed method was based on ion-pair extraction with bis-2-ethylhexylphosphate and derivatization with isobutylchloroformate. Quantification was carried out by the standard addition method using 2-ethylimidazole as internal standard. Reproducibility data from the complete procedure are presented. Mean recoveries were higher than 98%. The method was applied to green and roasted coffee samples from the two most important varieties, arabica and robusta, and to commercial "torrefacto" coffee blends. 4MI was not detected in the green coffee samples analysed and ranged from 0.307 to 1.241 mg/kg in roasted samples.

Influence of olive storage period on oil quality of three Portuguese cultivars of Olea europea, Cobrançosa, Madural, and Verdeal Transmontana.

Olives (Olea europaea cv. Cobrançosa, Madural, and Verdeal Transmontana) used for oil production were stored, in plastic containers, at 5 +/- 2 degrees C (70% relative humidity) for three different periods before oil extraction: 0, 7, and 14 days (T(0), T(7), and T(14), respectively). In the crop year 1997/1998 this procedure was done only for cv. Cobrançosa and in 1998/1999 for the three cultivars. After storage, the oils were extracted from the fruits, and the acidity, peroxide value, coefficients of specific extinction at 232 and 270 nm, stability, color, p-anisidine value, fatty acids, and tocopherols compositions were determined. The results confirm that storage of fruits produces losses in the olive oil quality. Acidity and stability to oxidation indicate a progressive deterioration of oil quality as fruit is stored. The storage time affects the total tocopherols contents, namely, alpha-tocopherol, which clearly decreased during fruit storage. The oil quality of the Verdeal Transmontana cultivar deteriorated more rapidly than that of Cobrançosa and Madural cultivars. This study also shows that cv. Cobrançosa, the main cultivar in the region, is a good choice in terms of final olive oil quality.

Phenolic profile evolution of different ready-to-eat baby-leaf vegetables during storage.

Ready-to-eat baby-leaf vegetables market has been growing and offering to consumers convenient, healthy and appealing products, which may contain interesting bioactive compounds. In this work, the composition and the evolution of the phenolic compounds from different baby-leaf vegetables during refrigerated storage was studied. The phenolic compounds were extracted using pressurized liquid extraction (PLE) and the phenolic profile of each sample was analyzed and quantified by using LC-MS and LC-DAD methods, respectively, at the beginning and at the end of a 10-day storage period. The baby-leaf vegetables studied included green lettuce, ruby red lettuce, swiss chard, spinach, pea shoots, watercress, garden cress, mizuna, red mustard, wild rocket and spearmint samples and a total of 203 phenolic compounds were tentatively identified and quantified. The main naturally phenolic compounds identified correspond to glycosylated flavonoids, with exception of green lettuce and spearmint leaves which had a higher content of hydroxycinnamic acids. Quantification of the main compounds showed a 10-fold higher content of total phenolic content of ruby red lettuce (483mgg(-1)) in relation to the other samples, being the lowest values found in the garden cress (12.8mgg(-1)) and wild rocket leaves (8.1mgg(-1)). The total phenolic content only showed a significant change (p<0.05) after storage in the green lettuce (+17.5%), mizuna (+7.8%), red mustard (-23.7%) and spearmint (-13.8%) leaves. Within the different classes of phenolic compounds monitored, the flavonols showed more stable contents than the hydroxycinnamic and hydroxybenzoic acids, although the behavior of each compound varied strongly among samples.

Iron oxide/gold core/shell nanomagnetic probes and CdS biolabels for amplified electrochemical immunosensing of Salmonella typhimurium.

There is an imminent need for rapid methods to detect and determine pathogenic bacteria in food products as alternatives to the laborious and time-consuming culture procedures. In this work, an electrochemical immunoassay using iron/gold core/shell nanoparticles (Fe@Au) conjugated with anti-Salmonella antibodies was developed. The chemical synthesis and functionalization of magnetic and gold-coated magnetic nanoparticles is reported. Fe@Au nanoparticles were functionalized with different self-assembled monolayers and characterized using ultraviolet-visible spectrometry, transmission electron microscopy, and voltammetric techniques. The determination of Salmonella typhimurium, on screen-printed carbon electrodes, was performed by square-wave anodic stripping voltammetry through the use of CdS nanocrystals. The calibration curve was established between 1×10(1) and 1×10(6) cells/mL and the limit of detection was 13 cells/mL. The developed method showed that it is possible to determine the bacteria in milk at low concentrations and is suitable for the rapid (less than 1h) and sensitive detection of S. typhimurium in real samples. Therefore, the developed methodology could contribute to the improvement of the quality control of food samples.

Multi-elemental analysis of ready-to-eat "baby leaf" vegetables using microwave digestion and high-resolution continuum source atomic absorption spectrometry.

The mineral content (phosphorous (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu)) of eight ready-to-eat baby leaf vegetables was determined. The samples were subjected to microwave-assisted digestion and the minerals were quantified by High-Resolution Continuum Source Atomic Absorption Spectrometry (HR-CS-AAS) with flame and electrothermal atomisation. The methods were optimised and validated producing low LOQs, good repeatability and linearity, and recoveries, ranging from 91% to 110% for the minerals analysed. Phosphorous was determined by a standard colorimetric method. The accuracy of the method was checked by analysing a certified reference material; results were in agreement with the quantified value. The samples had a high content of potassium and calcium, but the principal mineral was iron. The mineral content was stable during storage and baby leaf vegetables could represent a good source of minerals in a balanced diet. A linear discriminant analysis was performed to compare the mineral profile obtained and showed, as expected, that the mineral content was similar between samples from the same family. The Linear Discriminant Analysis was able to discriminate different samples based on their mineral profile.

Drug-delivery systems of green tea catechins for improved stability and bioavailability.

Numerous studies in humans, animal models and cell lines have suggested the potential benefits from the consumption of green tea polyphenols, including prevention of cancer and heart diseases. However these potential effects have been strongly limited by green tea catechins low bioavailability, which hinders the development of therapeutic applications. In this review formulations that are being proposed for delivery of green tea catechins are discussed. New delivery systems are presented as valid alternatives to overcome the limitations such as green tea catechins poor stability or intestinal absorption.

Sequential determination of fat- and water-soluble vitamins in green leafy vegetables during storage.

The simultaneous analysis of fat- and water-soluble vitamins from foods is a difficult task considering the wide range of chemical structures involved. In this work, a new procedure based on a sequential extraction and analysis of both types of vitamins is presented. The procedure couples several simple extraction steps to LC-MS/MS and LC-DAD in order to quantify the free vitamins contents in fresh-cut vegetables before and after a 10-days storage period. The developed method allows the correct quantification of vitamins C, B(1), B(2), B(3), B(5), B(6), B(9), E and provitamin A in ready-to-eat green leafy vegetable products including green lettuce, ruby red lettuce, watercress, swiss chard, lamb's lettuce, spearmint, spinach, wild rocket, pea leaves, mizuna, garden cress and red mustard. Using this optimized methodology, low LOQs were attained for the analyzed vitamins in less than 100 min, including extraction and vitamin analysis using 2 optimized procedures; good repeatability and linearity was achieved for all vitamins studied, while recoveries ranged from 83% to 105%. The most abundant free vitamins found in leafy vegetable products were vitamin C, provitamin A and vitamin E. The richest sample on vitamin C and provitamin A was pea leaves (154 mg/g fresh weight and 14.4 mg/100g fresh weight, respectively), whereas lamb's lettuce was the vegetable with the highest content on vitamin E (3.1 mg/100 g fresh weight). Generally, some losses of vitamins were detected after storage, although the behavior of each vitamin varied strongly among samples.

Electrochemical DNA-sensor for evaluation of total antioxidant capacity of flavours and flavoured waters using superoxide radical damage.

In this paper, a biosensor based on a glassy carbon electrode (GCE) was used for the evaluation of the total antioxidant capacity (TAC) of flavours and flavoured waters. This biosensor was constructed by immobilising purine bases, guanine and adenine, on a GCE. Square wave voltammetry (SWV) was selected for the development of this methodology. Damage caused by the reactive oxygen species (ROS), superoxide radical (O2·(-)), generated by the xanthine/xanthine oxidase (XOD) system on the DNA-biosensor was evaluated. DNA-biosensor encountered with oxidative lesion when it was in contact with the O2·(-). There was less oxidative damage when reactive antioxidants were added. The antioxidants used in this work were ascorbic acid, gallic acid, caffeic acid, coumaric acid and resveratrol. These antioxidants are capable of scavenging the superoxide radical and therefore protect the purine bases immobilized on the GCE surface. The results demonstrated that the DNA-based biosensor is suitable for the rapid assess of TAC in beverages.

Towards a reliable technology for antioxidant capacity and oxidative damage evaluation: electrochemical (bio)sensors.

To counteract and prevent the deleterious effect of free radicals the living organisms have developed complex endogenous and exogenous antioxidant systems. Several analytical methodologies have been proposed in order to quantify antioxidants in food, beverages and biological fluids. This paper revises the electroanalytical approaches developed for the assessment of the total or individual antioxidant capacity. Four electrochemical sensing approaches have been identified, based on the direct electrochemical detection of antioxidant at bare or chemically modified electrodes, and using enzymatic and DNA-based biosensors.