Six cultivars (Franquette, Marbot, Mayette, Mellanaise, Lara, and Parisienne) of walnuts (Juglans regia L.) were collected during the 2001 crop, from Braganç a, Portugal. Chemical composition, including moisture, total oil content, crude protein, ash, carbohydrates, and nutritional value, was evaluated. Fat was the predominant component, ranging from 62.3 to 66.5%. Total oil was extracted and analyzed for fatty acids, sterols, oxidative stability, and peroxide value. Fatty acids and sterols were determined by gas-liquid chromatography coupled to a flame ionization detector. Eighteen fatty acids were quantified. Polyunsaturated fatty acids and, in particular, linoleic acid were predominant. -Sitosterol, ∆ 5 -avenasterol, and campesterol were the major sterols found. Differences were observed among the studied cultivars, especially in peroxide values and in the sterol profile.

This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, sterols and fatty acids) as a tool to discriminate three varietal olive oils (Cvs. Cobrançosa, Madural and Verdeal Transmontana), which are permitted cultivars for the production of ''Trás-os-Montes olive oil'', a Portuguese protected designation of origin (PDO) product. The olives were collected during the year crop 2000/2001 from the same orchard, in order to eliminate the geographical and climatic influences. Lots with different maturation indices were prepared to allow the evaluation of the ripening stage on the characteristics of varietal olive oils produced from each cultivar. Statistical methods such as multivariate analysis of variance (MANOVA), principal components analysis (PCA) and cluster analysis were used to evaluate significant differences on the studied parameters. Regarding the results, the three cultivars were clearly discriminated.

Honey is a highly consumed natural product, not only for its taste and nutritional value, but also for its health benefits. Owing to characteristics that are essentially or exclusively related to the specific region or particular local environment and flora, honey can be classified as a premium product generally perceived as a high-quality and valued product because of its desirable flavor and taste. Consequently, honey has been a target of adulteration through inappropriate/fraudulent production practices and mislabeling origin. Globally, authentication of honey covers 2 main aspects: the production, with main issues related to sugar syrup addition, filtration, thermal treatment, and water content; and the labeled origin (geographical and/or botanical) and "organic" provenance. This review addresses all those issues, focusing on the approaches to detect the different types of honey adulteration. Due to the complex nature of honey and to the different types of adulteration, its authentication has been challenging and prompted the development of several advanced analytical approaches. Therefore, an updated, critical, and extensive overview on the current and advanced analytical methods targeting markers of adulteration/authenticity, including nontarget fingerprint approaches will be provided. The most recent advances on molecular, chromatographic, and spectroscopic methodologies will be described, emphasizing their pros and cons for the identification of botanical and geographical origins.

Winery by-products are a rich source of polyphenols, which have proven to have several beneficial biological properties, such as, antioxidant and antimicrobial activities. Therefore, this study aimed the extraction of polyphenols from winery by-products of two Portuguese red grape varieties, Touriga Nacional and Preto Martinho, and evaluate their phenolic profile, antioxidant properties and antimicrobial activity against antibiotic resistant bacteria. The polyphenols were extracted from the grapes' skins, seeds and stems. Extracts were analysed for total phenolic, anthocyanin and tannin contents, and the polyphenol profile was determined by High Performance Liquid Chromatography. The antioxidant activity of the extracts was determined by ABTS + and DPPH methods. Antimicrobial susceptibility assay was performed using Kirby-Bauer disc diffusion method. Preto Martinho variety presented a higher polyphenolic content than Touriga Nacional. Malvidin 3-O-glucoside was the most abundant compound found in the skins extracts in both varieties. The main phenolic compound found in the seeds and stems extracts was catechin. From the several flavonols quantified, rutin was the most abundant. For both varieties, the seeds extracts showed the highest antioxidant and antimicrobial properties, followed by the stems extracts. The extracts showed antibacterial activity against all tested strains except on gram-negative bacteria Salmonella enteritidis, Escherichia coli and Pseudomonas aeruginosa. These results show that, natural products, such as polyphenols, may represent a source for the development of novel antimicrobials to combat gram-positive resistant bacteria and possibly be used as natural food preservatives. However, they were not effective against gram-negative resistant bacteria which shows that polyphenols, alone, might not substitute antibiotics.

Qualitative and quantitative determinations of phenolic compounds were carried out on walnut leaves samples from six different cultivars, with the same agricultural, geographical and climatic conditions. The evolution of major phenolic compounds amounts was monitored from May to September. Two extractive procedures were assayed and best results were obtained using acidified water and a solid phase extraction column purification step. Qualitative analysis was performed by HPLC-DAD/MS and, in all samples, seven phenolic compounds were identified (3-caffeoylquinic, 3-p-coumaroylquinic and 4-p-coumaroylquinic acids, quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-xyloside, quercetin 3-rhamnoside) and two other partially identified phenolics (quercetin 3-pentoside and kaempferol 3-pentoside derivatives) were also detected. Quantification of phenolic compounds was performed by HPLC-DAD, which revealed that quercetin 3-galactoside was always the major compound while 4-p-coumaroylquinic acid was the minor one. The highest content of phenolics was found in May and July.

In the last few years, the consumption of dietary supplements, especially those having plants as ingredients, has been increasing due to the common idea that they are natural products posing no risks to human health. In the European Union and the United States, dietary supplements are legally considered as foods/special category of foods, thus are not being submitted to any safety assessment prior to their commercialization. Among the issues that can affect safety, adulteration by the illegal addition of pharmaceutical substances or their analogs is of major concern since unscrupulous producers can falsify these products to provide for quick effects and to increase sales. This review discusses the various classes of synthetic drugs most frequently described as being illegally added to dietary supplements marketed for weight loss, muscle building/sport performance and sexual performance enhancement. Information regarding regulation and consumption is also presented. Finally, several conventional and advanced analytical techniques used to detect and identify different adulterants in dietary supplements and therefore also in foods, with particular emphasis on plant food supplements, are critically described. This review demonstrates that dietary supplement adulteration is an emerging food safety problem and that an effective control by food regulatory authorities is needed to safeguard consumers.

Nineteen cultivars of hazelnuts (Corylus avellana L.) collected during the 2001 crop, from Vila Real, Portugal, were analysed for chemical composition, including moisture, total oil content, crude protein, ash, carbohydrates and nutritional value. Fat was the predominant component, ranging from 59.3 to 69.0%. Total oil was extracted and analysed for fatty acid and sterol compositions and oxidative stability. Fatty acid and sterol compositions were determined by Gas-Liquid Chromatography coupled to a Flame Ionisation Detector (GLC/FID). Monounsaturated fatty acids, particularly oleic acid, were predominant (78.7-84.6%). Total phytosterol content ranged from 133.8 to 263.0 mg/100 g of oil. Among the nine sterols identified and quantified, β-sitosterol was the major one with a mean percentage of 83.6%, while 5 -avenasterol and campesterol were the second and the third components of the group with mean values of 6.1 and 5.8%, respectively. Since hazelnut oil can be used in olive oil adulteration, the values obtained were compared with published mean values of olive oils from different geographical origins.

Species identification in meat products has grown in interest in recent years since these foodstuffs are susceptible targets for fraudulent labelling. In this work, a real-time PCR approach based on SYBR Green dye was proposed for the quantitative detection of pork meat in processed meat products. For the development of the method, binary meat mixtures containing known amounts of pork meat in poultry meat were used to obtain a normalised calibration model from 0.1 to 25% with high linear correlation and PCR efficiency. The method revealed high specificity by melting curve analysis, being successfully validated through its application to blind meat mixtures, which confirmed its adequacy for pork meat determination. The fully applicability of the method was further demonstrated in commercial meat products, allowing verification of labelling compliance and identification of meat species in processed foods.