Joana S. Amaral

Quantitative detection of poultry meat adulteration with pork by a duplex PCR assay.

A species-specific duplex polymerase chain reaction (PCR) assay was developed for the simultaneous detection of pork and poultry meat species using the mitochondrial cytb and 12S rRNA as target genes for pork and poultry, respectively. By the amplification of binary reference meat mixtures, a linear normalised calibration curve was obtained using the fluorescence intensities of PCR products for pork (149 bp) and poultry (183 bp) species. The proposed method allowed the quantification of pork meat addition to poultry meat in the range of 1-75%, with a sensitivity of 0.1%. The in-house validation using samples with known amounts of pork meat (1.0%, 2.5%, 7.5%, 20.0% and 40%) evidenced a high reproducibility of the methodology (coefficient of variation from 4.1% to 7.6%). The successful application of the duplex PCR was also demonstrated by the high correlation (R(2)=0.99) obtained from regression analysis between the predicted and the actual values of pork meat addition in blind meat mixtures. The suggested methodology presents a low cost, fast, easy and reliable alternative to estimate the level of poultry meat adulteration by the addition of pork meat.

A SYBR Green real-time PCR assay to detect and quantify pork meat in processed poultry meat products

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.

Adulteration of Dietary Supplements by the Illegal Addition of Synthetic Drugs: A Review

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.

HPLC/DAD analysis of phenolic compounds from lavender and its application to quality control

A reversed phase HPLC procedure is proposed for the determination of eight phenolic compounds (2-O-glucosilcoumaric acid, o-coumaric acid, rosmarinic acid, apigenin-7-O-glucoside, coumarin, herniarin, luteolin, and apigenin) in lavender. The chromatographic separation was achieved using a reversed-phase Spherisorb ODS 2 (5 μm particle size: 25.0 × 0.46 cm) column. From the several extractive solvents assayed, only ethanol was able to extract all the mentioned compounds. Best resolution was obtained using a gradient of water-formic acid (19:1) and acetonitrile. Ten samples were subjected to quantification, all of them showing a common composition pattern.

Phenolic profile of hazelnut (Corylus Avellana L.) leaves cultivars grown in Portugal

In this study, phenolic compounds of hazelnut leaves of 10 different cultivars with the same cultural, geographical, geological and climatic conditions were analyzed by HPLC/DAD and HPLC/DAD/MS/MS – ESI. Eight phenolic compounds (3-caffeoylquinic acid, 5-caffeoylquinic acid, caffeoyltartaric acid, p-coumaroyltartaric acid, myricetin 3-rhamnoside, quercetin 3-glycoside, quercetin 3-rhamnoside and kaempferol 3-rhamnoside) were identified and quantified. All of the analyzed samples showed a similar phenolic profile, in which myricetin 3-rhamnoside and quercetin 3-rhamnoside were the major compounds and caffeoyltartaric and p-coumaroyltartaric acids were present in vestigial amounts.

Identification of hare meat by a species-specific marker of mitochondrial origin

Meat species identification in food has gained increasing interest in recent years due to public health, economic and legal concerns. Following the consumer trend towards high quality products, game meat has earned much attention. The aim of the present work was to develop a DNA-based technique able to identify hare meat. Mitochondrial cytochrome b gene was used to design species-specific primers for hare detection. The new primers proved to be highly specific to Lepus species, allowing the detection of 0.01% of hare meat in pork meat by polymerase chain reaction (PCR). A real-time PCR assay with the new intercalating EvaGreen dye was further proposed as a specific and fast tool for hare identification with increased sensitivity (1pg) compared to end-point PCR (10pg). It can be concluded that the proposed new primers can be used by both species-specific end-point PCR or real-time PCR to accurately authenticate hare meat.

Do Cultivar, Geographical Location and Crop Season Influence Phenolic Profile of Walnut Leaves?

Walnut leaves from nine different cultivars (Arco, Franquette, Hartley, Lara, Marbot, Mayette, Meylannaise, Parisienne and Rego) were studied for their phenolic compounds. Samples were harvested along three consecutive years, at two different geographical locations, in order to evaluate if significant differences in the phenolics composition can be related with genetic, climatic or geographical factors. Nine compounds (3-caffeoylquinic, 3-p-coumaroylquinic and 4-p-coumaroylquinic acids, quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-xyloside, quercetin 3-rhamnoside, a quercetin 3-pentoside derivative and a kaempferol 3-pentoside derivative) were quantified using an HPLC-DAD methodology. The qualitative profiles were identical for all samples, but differences were observed in terms of individual compounds’ contents. Multivariate statistical analysis was carried out, showing that significant differences exist among production years, which can be related to climatic reasons.

Antimicrobial activity of essential oils from mediterranean aromatic plants against several foodborne and spoilage bacteria

The antimicrobial activity of essential oils extracted from a variety of aromatic plants, often used in the Portuguese gastronomy was studied in vitro by the agar diffusion method. The essential oils of thyme, oregano, rosemary, verbena, basil, peppermint, pennyroyal and mint were tested against Gram-positive (Listeria monocytogenes, Clostridium perfringens, Bacillus cereus, Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, and Staphylococcus epidermidis) and Gram-negative strains (Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa). For most essential oils examined, S. aureus, was the most susceptible bacteria, while P. aeruginosa showed, in general, least susceptibility. Among the eight essential oils evaluated, thyme, oregano and pennyroyal oils showed the greatest antimicrobial activity, followed by rosemary, peppermint and verbena, while basil and mint showed the weakest antimicrobial activity. Most of the essential oils considered in this study exhibited a significant inhibitory effect. Thyme oil showed a promising inhibitory activity even at low concentration, thus revealing its potential as a natural preservative in food products against several causal agents of foodborne diseases and food spoilage. In general, the results demonstrate that, besides flavoring the food, the use of aromatic herbs in gastronomy can also contribute to a bacteriostatic effect against pathogens.

Development of chitosan-based antimicrobial leather coatings.

The development of antimicrobial coatings for footwear components is of great interest both from industry and consumers point of view. In this work, antimicrobial leather materials were developed taking advantage of chitosan intrinsic antimicrobial activity and film forming capacity. Considering the specificities of the leather tanning industry, different coating technologies, namely drum, calender and spray, were tested, being the best results achieved with the drum. This last approach was further investigated to assess the effect of chitosan content, type of solubilizing acid, and impregnation time on the achieved antimicrobial capacity. Considering chitosan price (economic reasons) and the obtained results (antimicrobial activity and coating effectiveness, as inspected by SEM), the impregnation in the drum using a chitosan content of 1% (w/v) in a formic acid solution during 2h, is proposed as the best option for obtaining leather with antimicrobial capacity.

Tetraoxygenated xanthones from centaurium erythraea

Abstract Three tetraoxygenated xanthones, 1,6-dihydroxy-3,5-dimethoxyxanthone, 3-hydroxy-1,5,6-trimethoxyxanthone and 1,3,5-trihydroxy-2-methoxyxanthone, were isolated for the first time from the aerial parts of C. erythraea. Their structures were established by spectroscopic means and by comparison with literature references.