Browsing by Author "Mafra, Isabel"
Now showing 1 - 10 of 109
Results Per Page
Sort Options
- Advances in Authenticity Testing for Meat SpeciationPublication . Amaral, Joana S.; Meira, L.; Oliveira, Beatriz; Mafra, IsabelNowadays, and particularly after the horse meat scandal in Europe, consumers are increasingly aware of the problem of food adulteration and consequently demand clear and reliable information about the composition of foods they are buying and eating. Meat, a highly appreciated premium source of protein, is among the foods most prone to suffer adulteration for economic gain. According to EU legislation laying down the general principles and requirements of food law (European Commission, 2002) and EU labeling regulations (European Commission, 2001), meat products should be accurately labeled regarding their species content, with food adulteration and misleading information being considered illegal. However, because of its high demand and value, frauds in the meat industry and retail markets have become a widespread problem, especially in ground and comminuted meat products.
- Animal species authentication in dairy productsPublication . Mafra, Isabel; Honrado, Mónica; Amaral, Joana S.Milk is one of the most important nutritious foods, widely consumed worldwide, either in its natural form or via dairy products. Currently, several economic, health and ethical issues emphasize the need for a more frequent and rigorous quality control of dairy products and the importance of detecting adulterations in these products. For this reason, several conventional and advanced techniques have been proposed, aiming at detecting and quantifying eventual adulterations, preferentially in a rapid, cost-effective, easy to implement, sensitive and specific way. They have relied mostly on electrophoretic, chromatographic and immunoenzymatic techniques. More recently, mass spectrometry, spectroscopic methods (near infrared (NIR), mid infrared (MIR), nuclear magnetic resonance (NMR) and front face fluorescence coupled to chemometrics), DNA analysis (real-time PCR, high-resolution melting analysis, next generation sequencing and droplet digital PCR) and biosensors have been advanced as innovative tools for dairy product authentication. Milk substitution from high-valued species with lower-cost bovine milk is one of the most frequent adulteration practices. Therefore, this review intends to describe the most relevant developments regarding the current and advanced analytical methodologies applied to species authentication of milk and dairy products.
- Antioxidant profiles of soybean oil obtained from genetically modified seedsPublication . Costa, Joana; Amaral, Joana S.; Mafra, Isabel; Oliveira, BeatrizSoybean oil is a rich source of tocopherols, commonly known as Vitamin E, which are important antioxidants that occur naturally in vegetable oils. These compounds are believed to be involved in a diversity of physiological and biochemical functions, mainly due to their antioxidant activity but also because they can act as membrane stabilizers.
- Applicability of DNA-based methods for food authenticationPublication . Mafra, Isabel; Amaral, Joana S.; Costa, Joana; Soares, Sónia; Oliveira, BeatrizAuthenticity evaluation of foods encompasses many issues, including the entire or partial fraudulent substitution of higher commercial value constituents by others with lower value and the presence of undeclared ingredients. To address the referred food authenticity problems, several! Analytical methodologies have been developed at REQ.UIMTE during the last years. Due to its fastness, sensitivity and high specificity, the application of molecular biology techniques has proved to be an effective alternative to other methodologies for the identification of species in foods. Among other works, we have applied DNA analysis coupled to polymerase chain reaction (PCR) for the detection of frauds in the meat industry, namely to detect and quantify the addition of soybean as substitute of meat, the presence of pork in processed poultry meat products, the presence of horse in beef products, and the identification of several species (including hare, red dear, duck, partridge, pheasant, cow, etc.) in traditional game meat sausages. More recently, we also started the development of methodologies for the botanical origin identification of honey, based on the DNA analysis of pollen present in honey, and also for the authentication of medicinal plants used in plant food supplements
- Applicability of HRM analysis for carnaroli rice authentication based on polymorphisms of the waxy genePublication . Grazina, Liliana; Costa, Joana; Amaral, Joana S.; Garino, Cristiano; Arlorio, Marco; Oliveira, Beatriz; Mafra, IsabelRice (Oryza sativa L.) is a staple food and one of the most important cereals in the worldwide. Italy, the leading rice producer in Europe, holds nearly 200 different varieties in the available germplosm [1]. The Carnaroli rice is a high quality and priced variety belonging to the group of ja ponica ecotype, produced mainly in Piedmont. it is considered one of the finest Italian rice varieties due to its excellent cooking resistance, given by a low tendency to lose starch and a good ability to absorb liquid while creaming, being, thus, ideal for the preparation of traditional risotto. Italian rice varieties hove different characteristics, from which the starch composition is a highly relevant parameter. Together with amylopectin, amylose is the main component of starch, whose ratio is determinant for the rice cooking properties. After cooking, varieties with high amylose content have dry, firm and separate groins, while low amylose ones usually hove tender, cohesive and glossy texture [2]. Amylose synthesis is catalysed by the granule bound starch synthase (GBSS) that is encoded by the Waxy gene (Wx), being located on the chromosome 6. Various nucleotide polymorphisms have been associated with the Wx gene, namely (CT)n repeats and several single nucleotide polymorphisms (SNP) [2]. The aim of this work was to propose a new method based on high resolution melting (HRM) analysis, exploiting those polymorphisms to differentiate Carnaroli rice from other closely related varieties.
- Assessing the effect of pharmaceutical excipients on the DNA extraction from plant food supplementsPublication . Costa, Joana; Fernandes, Telmo J.R.; Amaral, Joana S.; Oliveira, Beatriz; Mafra, Isabelin the EU market as ingredients in formulations, which are sold as plant food supplements (PFS). Among the several issues that may affect the safety of PFS, the most relevant concerns aduÍterations by the illegal addition of pharmaceutical drugs and/or the swap/ misidentification ofplant material, with cases of acate toxicity already reported [l]. Owing to the high similarity and distinct therapeutic uses ofseveral medicinal plants, accurate and fast methodologies allowing their distincüon are required. For that purpose, DNA-based methods are considered fast, sensitive and highly specific tools, allowing the unequivocal identification of plant species. Up to date, most of DNA methodologies reporting the identification of plant species essentially concern medicinal plants [2], with few works being developed for the authentication of PFS.
- Assessing the variability of the fatty acid profile and cholesterol content of meat sausagesPublication . Amaral, Joana S.; Soares, Sónia; Mafra, Isabel; Oliveira, BeatrizEighteen different brands of meat sausages including pork, poultry and the mixture of both meats (pork and poultry) in sausages, were analysed for their nutritional composition (total fat, moisture, crude protein and ash), cholesterol content and fatty acid composition. As expected, the pork Frankfurter sausages presented a higher fat content compared to sausages that include poultry meat in their composition. A multivariate statistical analysis was applied to the data showing the existence of significant differences among samples. Regarding fatty acid composition, significant differences were verified in canonical variate plots when the samples were grouped by sausage type, suggesting that the fatty acid profile is strongly influenced by the type of meats, as well as other ingredients such as vegetable oil and lard, used in its formulation. The group of poultry Frankfurter sausages presented lower levels of SFA and higher levels of PUFA, which can point to a healthier profile compared to the pork and meat mixture sausages. Nevertheless, some poultry sausages showed a higher cholesterol content compared to the pork Frankfurters. The lowest mean cholesterol content was obtained for the group of pork Frankfurters, which somehow contradicts the consumers' idea that pork meat products should be avoided due to its high cholesterol levels.
- Autenticação de produtos cárneos com a designação Halal: Deteção e quantificação de derivados de suíno (Sus scrofa)Publication . Amaral, Joana S.; Costa, Joana; Mafra, Isabel; Oliveira, BeatrizDevido aos recentes escândalos alimentares relacionados com adulterações em produtos cárneos, tem-se assistido a uma maior atenção por parte dos consumidores e autorida-des sobre a ocorrência de fraudes neste setor, especialmen-te no que respeita a substituição de carne de espécies ani-mais de valor elevado por proteínas musculares de mais baixo custo. Em particular, devido ao seu baixo preço e ele-vada disponibilidade, a carne de porco e/ou derivados de suíno (gordura, plasma, colagénio, entre outros) podem ser fraudulentamente adicionados em produtos cárneos, tendo por objetivo o aumento de lucros de fabricantes pouco es-crupulosos [1,2]. Para além destas práticas representarem uma fraude económica, a presença de espécies animais não declaradas na rotulagem é algo que causa elevada preocu-pação em certos grupos religiosos para os quais o consumo de determinadas espécies é proibido.
- Authentication of a traditional game meat sausage (Alheira) by species-specific PCR assays to detect hare, rabbit, red deer, pork and cow meatsPublication . Amaral, Joana S.; Santos, Cristina G.; Melo, Vítor S.; Oliveira, Beatriz; Mafra, IsabelAlheira is a traditional meat product that is typical from the Northeast region of Portugal and much appreciated. It is a sort of sausage produced industrially or by small artisanal producers, having wheat bread and meats as main ingredients. Game meat Alheira (Alheira de caça) is considered one of the most attractive products since it should include different game meats. The aim of the present work was to identify the species of origin of meats added to game meat Alheira samples to verify their compliance with labelling. Species-specific PCR assays targeting mitochondrial genes of rabbit, hare, red deer, cow and pork were optimised and applied to industrial and artisanal samples. The assays revealed adequate specificity for each of the targeted species, with sensitivities of 0.01-0.1%. Results of the evaluation of 18 commercial samples identified several inconsistencies with labelling, namely the absence of declared game species (red deer, hare and rabbit) in ten samples and the presence of undeclared cow species in nine of the analysed samples. These findings indicate the occurrence of misleading labelling, suggesting the adulteration by substitution of game meats by cow meat to reduce production costs and the need to protect and valorise this kind of traditional food product.
- Authentication of Argan (Argania spinosa L.) oil using novel DNA-based approaches: detection of olive and soybean oils as potential adulterantsPublication . Amaral, Joana S.; Raja, Fatima Zahra; Costa, Joana; Grazina, Liliana; Villa, Caterina; Charrouf, Zoubida; Mafra, IsabelArgan oil is a traditional product obtained from the fruits of the argan tree (Argania spinosa L.), which is endemic only to Morocco. It is commercialized worldwide as cosmetic and food-grade argan oil, attaining very high prices in the international market. Therefore, argan oil is very prone to adulteration with cheaper vegetable oils. The present work aims at developing novel real-time PCR approaches to detect olive and soybean oils as potential adulterants, as well as ascertain the presence of argan oil. The ITS region, matK and lectin genes were the targeted markers, allowing to detect argan, olive and soybean DNA down to 0.01 pg, 0.1 pg and 3.2 pg, respectively, with real-time PCR. Moreover, to propose practical quantitative methods, two calibrant models were developed using the normalized ΔCq method to estimate potential adulterations of argan oil with olive or soybean oils. The results allowed for the detection and quantification of olive and soybean oils within 50–1% and 25–1%, respectively, both in argan oil. Both approaches provided acceptable performance parameters and accurate determinations, as proven by their applicability to blind mixtures. Herein, new qualitative and quantitative PCR assays are proposed for the first time as reliable and high-throughput tools to authenticate and valorize argan oil.