Browsing by Author "Villa, Caterina"
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- 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.
- Detection of soybean oil as a potential adulterant of argan oil based on a novel DNA approachPublication . Raja, Fatima Zahra; Amaral, Joana S.; Charrouf, Zoubida; Costa, Joana; Grazina, Liliana; Villa, Caterina; Kartah, Badr Eddine; Oliveira, Beatriz; Mafra, IsabelArgan oil is a non-refined vegetable oil obtained from the fruits of the argan tree (Argania spinosa L.) and produced almost exclusively in the southwestern Morocco, where the argan forest is found. Different grades of argan oil are available, namely edible/food and cosmetic grades, depending on the use of roasted or raw kernels, respectively. Argan oil is considered one of the most prized oils in the world, with its demand growing worldwide mainly due to its success as an ingredient in cosmetic products. In Europe, the price of the edible grade oil is also very high as it is perceived as a luxury product [1]. Being a premium product, argan oil is highly prone to adulteration by admixing with cheaper vegetable oils or even its total substitution. Therefore, it is important to develop methodologies that can be used in the control of the authenticity of pure argan oil. Considering that several factors can affect the chemical composition of the oil, in this work novel approaches based on DNA markers are proposed to detect the presence of soybean oil as adulterant of argan oil.
- Development of new molecular tools to assess argan oil authenticity: detection of olive oil as a potential adulterantPublication . Raja, Fatima Zahra; Costa, Joana; Amaral, Joana S.; Charrouf, Zoubida; Grazina, Liliana; Villa, Caterina; Kartah, Badr Eddine; Oliveira, Beatriz; Mafra, IsabelArgan oil is a traditional product obtained from the argan tree (Arganiaspinosa L.),whichis endemic only to Morocco[1].Both cosmetic and food grade argan oil are commercialized worldwide, attaining very high prices in the international market.For that reason, argan oil is very prone to be adulterated, in particular with cheaper vegetable oils. Therefore, it is important to develop methodologies that can be used in control and inspection programs in order to guarantee argan oil authenticity and quality. In particular, there is the need for methodologies that allow the accurate identification of vegetable oils illegally added to argan oil. The present work aims at developing novel approaches based on DNA markers to detect the presence of adulterants, using olive oil as case study. In silico analysis was performed for the design of Oleaeuropea L. and A. spinosa L. specific primers targeting the chloroplastidialmatKgeneand the ITS2 region, respectively. Samples of authentic argan oil were acquired from a producing cooperativein Morocco, while olive oil samples were obtained from local stores in Portugal. Cross-reactivity was assayed using DNA extracts from other edible and oil producing plant species (n=17). Binary model mixtures were prepared with the addition of known amounts of olive oil in argan oil in the proportions of 50, 25, 5, 1% (w/w), followed by a pre-concentration by centrifugation. DNA was extracted using the Nucleospin Plant kit, protocol B. according to the manufacturer instructions. Specificity and sensitivity of the designed primers were assessed by qualitative PCR. Species-specific PCR assays were successfully developed, producing amplicons of 109 and 117 bp for olive and argan, respectively, down to 0.01 pg of DNA for both species. The application of the olive-specific PCR assay to DNA extracts of binary mixtures enabled the clear detection of 1%. Subsequently, a real-time PCR assay with EvaGreen dye was developed for quantitative analysis using the normalised ΔCq method. The assay confirmed the limit of detection of 1% of olive oil, in a dynamic range of 1-50%, with acceptable correlation coefficient and PCR efficiency (81.1%), considering the type of food matrix. Both, qualitative and quantitative PCR assays can provide simple, fast and high-throughput tools to detect the presence of adulterant oils in argan oil.
- A novel DNA-based approach for argan oil authentication: detection of olive oil as a potential adulterantPublication . Mafra, Isabel; Raja, Fatima Zahra; Costa, Joana; Amaral, Joana S.; Grazina, Liliana; Villa, Caterina; Kartah, Badr Eddine; Charrouf, Zoubida; Oliveira, BeatrizArgan oil is a non-refined vegetable oil produced fron the argan tree (Argania spinosa L.) a species endemic only in the South-western Maroco.