Browsing by Author "Costa, Joana"
Now showing 1 - 10 of 62
Results Per Page
Sort Options
- 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.
- 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 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.
- Authentication of carnaroli rice by HRM analysis targeting nucleotide polymorphisms in the Alk and Waxy genesPublication . Grazina, Liliana; Costa, Joana; Amaral, Joana S.; Garino, Cristiano; Arlorio, Marco; Mafra, IsabelCarnaroli is a high quality and priced variety, being considered as one of the finest Italian rice varieties due to its sensorial and rheological properties and, thus being a potential adulteration target. The present work aimed at exploiting polymorphisms in the Alk (A/G and GC/TT in exon 8) and Waxy ((CT)n and G/T in intron 1) genes by HRM analysis to differentiate Carnaroli rice from closely related varieties. The HRM method targeting the Alk gene did not allow gathering the Carnaroli subgroup genotypes in the same cluster. The HRM approach targeting Waxy gene successfully discriminated the varieties sold as Carnaroli from all the others with high level of confidence (>98%), which corroborated sequencing data. Its applicability to commercial rice samples was successful. Therefore, the proposed new HRM method can be considered a simple, specific, high-throughput and cost-effective tool for the authentication of Carnaroli rice, contributing to valorise such premium variety.
- Authentication of ginkgo biloba herbal products by a novel quantitative real-time PCR approachPublication . Grazina, Liliana; Amaral, Joana S.; Costa, Joana; Mafra, IsabelGinkgo biloba is a widely used medicinal plant. Due to its potential therapeutic effects, it is an ingredient in several herbal products, such as plant infusions and plant food supplements (PFS). Currently, ginkgo is one of the most popular botanicals used in PFS. Due to their popularity and high cost, ginkgo-containing products are prone to be fraudulently substituted by other plant species. Therefore, this work aimed at developing a method for G. biloba detection and quantification. A new internal transcribe spacer (ITS) marker was identified, allowing the development of a ginkgo-specific real-time polymerase chain reaction (PCR) assay targeting the ITS region, with high specificity and sensitivity, down to 0.02 pg of DNA. Additionally, a normalized real-time PCR approach using the delta cycle quantification (ΔCq) method was proposed for the effective quantification of ginkgo in plant mixtures. The method exhibited high performance parameters, namely PCR efficiency, coefficient of correlation and covered dynamic range (50-0.01%), achieving limits of detection and quantification of 0.01% (w/w) of ginkgo in tea plant (Camellia sinensis). The quantitative approach was successfully validated with blind mixtures and further applied to commercial ginkgo-containing herbal infusions. The estimated ginkgo contents of plant mixture samples suggest adulterations due to reduction or almost elimination of ginkgo. In this work, useful and robust tools were proposed to detect/quantify ginkgo in herbal products, which suggests the need for a more effective and stricter control of such products.
- Authentication of incense (Pittosporum undulatum Vent.) honey from the Azores (Mel dos Acores) by a novel real-time PCR approachPublication . Lopes, Ana; Moura, Monica B.M.V.; Grazina, Liliana; Costa, Joana; Amaral, Joana S.; Pinto, M. Alice; Mafra, Isabel'Mel dos Acores' is a unique nectar honey produced from the exceptional and diverse flora of the Azores archipelago, categorised as incense honey ('mel de incenso') or multifloral honey ('mel multiflora'). Incense honey should contain over 30 % of pollen grains of Pittosporum undulatum Vent. In this work, a real-time PCR method targeting the ITS region was proposed for the first time to detect P. undulatum in the honey from the Azores. The approach exhibited high analytical performance, achieving a quantification limit of 0.01 pg of incense DNA. The method was successfully applied to 22 honey samples, from which incense was detected in all 9 monofloral incense honeys and in 5 out of 10 multifloral samples from the Azores. Generally, the quantitative results for incense DNA were in good agreement with the melissopalynological data. Therefore, a simple, cost-effective and reliable tool was herein proposed to authenticate and valorise the Azores honey.
- Botanical authentication of globe artichoke-containing foods: Differentiation of Cynara scolymus by a novel HRM approachPublication . Grazina, Liliana; Batista, Andreia; Amaral, Joana S.; Costa, Joana; Mafra, IsabelCynara scolymus L., known as globe artichoke, is a medicinal plant widely used in plant food supplements (PFS) and herbal infusions due to its beneficial health properties. The high demand for artichoke-containing products can lead to adulteration practices. In this work, a real-time polymerase chain reaction (PCR) system coupled to high-resolution melting (HRM) analysis was proposed to differentiate C. scolymus from other Cynara species. Hence, a Cynara-specific real-time PCR assay was successfully developed with high analytical performance, achieving a sensitivity of 0.4 pg of globe artichoke DNA. HRM analysis enabled the discrimination of C. scolymus, with a high level of confidence (>98%), corroborating sequencing data. Application results to artichokecontaining PFS and mixed herbal infusions allowed confirming the presence of C. scolymus in 38% of the samples, suggesting the substitution/mislabelling of globe artichoke in 2 samples and the need for further efforts to increase DNA amplifiability of PFS.