Browsing by Author "Sierra, Isabel"
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- An improved and miniaturized analytical strategy based on μ-QuEChERS for isolation of polyphenols. A powerful approach for quality control of baby foodsPublication . Casado, Natalia; Perestrelo, Rosa; Silva, Catarina L.; Sierra, Isabel; Câmara, José S.An improved and miniaturized quick, easy, cheap, effective, rugged and safe (μ-QuEChERS) strategy combined with ultra-high pressure liquid chromatography coupled to a photodiode array detection system (UHPLC-PDA) was developed and optimized for the determination of twelve polyphenols in different baby foods samples. The proposed analytical approach proved to be highly cost-effective and environmentally friendly, since it showed good extraction efficiency using few amounts of sample (0.3 g), organic solvents (1000 μL), clean-up sorbents (87.5 mg) and partitioning salts (0.2 g), producing minimal waste disposal and reducing analysis time. Method performance was validated in terms of selectivity, linearity, limits of detection and quantification, matrix effects, precision and accuracy using different baby food matrices according to their composition. The overall average recoveries ranged from 71 to 100% with relative standard deviations lower than 6% (n = 18). The method was successfully applied to commercial baby food samples (including pureed solids, juices and porridges), and their total phenolic content (TPC) and antioxidant capacity (RSA) were also investigated. Results allowed characterizing the abundance of the selected polyphenols in the samples, and the highest RSA and TPC were found in the fruit-based baby foods. Thus, this work represents a first approach to determine the nutritional quality of these products.
- Comparison of high-throughput microextraction techniques, MEPS and μ-SPEed, for the determination of polyphenols in baby food by ultrahigh pressure liquid chromatographyPublication . Casado, Natalia; Perestrelo, Rosa; Silva, Catarina L.; Sierra, Isabel; Câmara, José S.In this study, two different high-throughput microextraction techniques, microextraction by packed sorbents (MEPS) and micro solid phase extraction (μ-SPEed®), were evaluated and compared, regarding the performance criteria, for the isolation of polyphenols from baby foods prior to their determination by ultrahigh pressure liquid chromatography (UHPLC). To achieve the best performance, influential parameters affecting extraction efficiency (including type of sorbent, number of extraction cycles, pH, elution solvent and elution volume) were systematically studied and optimized. To enable an effective comparison, selectivity, linear dynamic range, method detection (LODs) and quantification limits (LOQs), accuracy, precision and extraction yields, were determined and discussed for both techniques. Both methods provided the analytical selectivity required for the analysis of polyphenols in baby foods. However, μ-SPEed® sample treatment in combination with UHPLC-PDA has demonstrated to be more sensitive, selective and efficient than MEPS. Appropriate linearity in solvent and matrix-based calibrations, very low LODs and LOQs, ranging between 1.37 and 13.57 μg kg-1 and 4.57 - 45.23 μg kg-1, respectively, suitable recoveries (from 67 to 97%) and precision (RSD values < 5%) were achieved for the selected analytes by μ-SPEed®/UHPLC-PDA. Finally, the validated methodologies were applied to different commercial baby foods. Gallic acid, chlorogenic acid, epicatechin, ferulic acid, rutin, naringenin and myricetin are the most dominant polyphenols present in the studied baby food samples. The proposed methodology revealed a promising approach to evaluate the nutritional quality of this kind of products.
- Evaluation of the transfer and occurrence of opium alkaloids in poppy seed teas using preconcentrations with µSPEed® followed by GC-MS analysisPublication . Casado-Hidalgo, Gema; Perestrelo, Rosa; Morante-Zarcero, Sonia; Câmara, José S.; Sierra, Isabel; Câmara, José; Perestrelo, RosaIntoxication due to the consumption of poppy seed teas has been reported due to their contamination with opium alkaloids (OAs). In this work, an efficient methodology based on microsolid-phase extraction (µSPEed®) followed by gas chromatography–mass spectrometry (GC-MS) has been optimized to quantify five OAs in poppy seed teas. Nine cartridges (C4, C8, C18, silica, APS, PFAs, PS/DVB-RP, PS/DVB-SCX and PS/DVB-SAX), pH levels, cycles and elution solvents were evaluated. The method was validated and applied to study the transfer of OAs by evaluating water temperatures, infusion times and seed amounts. The highest transfer rates (71% for morphine, 96% for thebaine, and 100% for codeine, noscapine and papaverine) were achieved at 90°C, 5 min, with 4 g. These conditions were used to quantify the OAs in four teas prepared from different seeds. A high amount of morphine (1563 µg/L) was found in one tea, indicating that the seeds had a concentration twice the maximum limit, highlighting the need to warn the population of this dangerous practice.
- Evaluation of tropane alkaloids in teas and herbal infusions: effect of brewing time and temperature on atropine and scopolamine contentPublication . González-Gómez, Lorena; Morante-Zarcero, Sonia; Pereira, Jorge A. M.; Câmara, José S.; Sierra, Isabel; Augusto Machado Pereira, Jorge; Câmara, JoséAtropine and scopolamine belong to the tropane alkaloid (TA) family of natural toxins. They can contaminate teas and herbal teas and appear in infusions. Therefore, this study focused on analyzing atropine and scopolamine in 33 samples of tea and herbal tea infusions purchased in Spain and Portugal to determine the presence of these compounds in infusions brewed at 97 °C for 5 min. A rapid microextraction technique (µSPEed®) followed by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was used to analyze the selected TAs. The results showed that 64% of the analyzed samples were contaminated by one or both toxins. White and green teas were generally more contaminated than black and other herbal teas. Of the 21 contaminated samples, 15 had concentrations above the maximum limit for liquid herbal infusions (0.2 ng/mL) set by Commission Regulation (EU) 2021/1408. In addition, the effects of heating conditions (time and temperature) on atropine and scopolamine standards and naturally contaminated samples of white, green, and black teas were evaluated. The results showed that at the concentrations studied (0.2 and 4 ng/mL), there was no degradation in the standard solutions. Brewing with boiling water (decoction) for 5 and 10 min allowed for higher extraction of TAs from dry tea to infusion water.
- Green extraction approach based on μSPEed® followed by HPLC-MS/MS for the determination of atropine and scopolamine in tea and herbal tea infusionsPublication . González-Gómez, Lorena; Pereira, Jorge A. M.; Morante-Zarcero, Sonia; Câmara, José S.; Sierra, Isabel; Augusto Machado Pereira, Jorge; Câmara, Joséliquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been proposed for the analysis of atropine and scopolamine in tea and herbal tea infusions. For this, a digiVOL® Digital Syringe was used with different sorbents and working conditions to obtain a fast and efficient µSPEed® extraction. The best performance was achieved with a PS/DVB sorbent phase, sample loading of 5 × 500 µL and elution with 2 × 100 µL aliquots of methanol. The strategy based on µSPEed® followed by HPLC-MS/MS was validated, attaining quantitation limits lower than 0.15 ng mL− 1 and recoveries between 94 and 106% for both analytes and applied to seventeen tea and herbal tea infusions. Fourteen infusions showed contamination with one or both analytes above the maximum content legislated (sum of atropine and scopolamine < 0.2 ng mL− 1).
- Improved analytical approach for determination of tropane alkaloids in leafy vegetables based on µ-QuEChERS combined with HPLC-MS/MSPublication . González-Gómez, Lorena; Morante-Zarcero, Sonia; Pereira, Jorge A. M.; Câmara, José S.; Sierra, Isabel; Augusto Machado Pereira, JorgeThis work presents an optimized methodology based on the miniaturization of the original QuEChERS (μ-QuEChERS) followed by liquid chromatography coupled to mass spectrometry (HPLC-MS/MS) for the determination of tropane alkaloids (TAs), atropine, and scopolamine in leafy vegetable samples. The analytical methodology was successfully validated, demonstrating quantitation limits (MQL) ≤ 2.3 ng/g, good accuracy, and precision, with recoveries between 90–100% and RSD ≤ 13% for both analytes. The method was applied to the analysis of TA-producing plants (Brugmansia versicolor, Solandra maxima, and Convolvulus arvensis). High concentrations of scopolamine were found in flowers (1771 mg/kg) and leaves (297 mg/kg) of B. versicolor. The highest concentration of atropine was found in flowers of S. maxima (10.4 mg/kg). Commercial mixed leafy vegetables contaminated with B. versicolor and S. maxima were analysed to verify the efficacy of the method, showing recoveries between 82 and 110% for both analytes. Finally, the method was applied to the analysis of eighteen samples of leafy vegetables, finding atropine in three samples of mixed leafy vegetables, with concentrations of 2.7, 3.2, and 3.4 ng/g, and in nine samples with concentrations ≤MQL. In turn, scopolamine was only found in a sample of chopped Swiss chard with a concentration ≤MQL.
- Spices volatilomic fingerprinting: a comprehensive approach to explore its authentication and bioactive propertiesPublication . Izcara, Sergio; Perestrelo, Rosa; Morante-Zarcero, Sonia; Sierra, Isabel; Câmara, José S.; Perestrelo, Rosa; Izcara Sierra, SergioVolatile organic metabolites (VOMs) present in different spices can provide distinct analytical biosignatures related to organoleptic properties and health benefits. This study aimed to establish the volatilomic fingerprint of six of the most consumed spices all over the world (saffron (Crocus sativus L.), cinnamon (Cinnamomum verum), cumin (Cuminum cyminum L.), black pepper, (Piper nigrum L.), sweet paprika (Capsicum annuum L.), and curry (a mix of different herbs and spices)). Based on headspace solid phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) analysis, this is a powerful strategy to explore and establish the spice’s volatile pattern and unravel the potential health benefits related to the most important VOMs identified in each spice. This comprehensive knowledge will help in the definition of their authenticity, while simultaneously protecting against potential frauds and adulterations. A total of 162 VOMs were identified. Semi-quantitative assessments revealed that terpenoids and sesquiterpenoids amounted to the major volatile class in the investigated spices, except for cinnamon, where carbonyl compounds are the major group. Most of the studied spices comprised key characteristics of aroma and health bioactive compounds, e.g., dihydrojuneol in saffron, cinnamaldehyde in cinnamon, cuminaldehyde in cumin and curry, and caryophyllene in black pepper. The principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) successfully discriminated the investigated spices, being α-cubebene, 3-methyl butanal, β-patchoulene and β-selinene, the most important VOMs (highest VIP’s) that contributed to its discrimination. Moreover, some VOMs have a high influence on the spice’s bioactive potential, helping to prevent certain diseases including cancer, inflammatory-related diseases, diabetes, and cardiovascular diseases.
- Volatilomic fingerprinting from edible flowers. Unravelling some impact compounds behind its attractivenessPublication . Izcara, Sergio; Perestrelo, Rosa; Morante-Zarcero, Sonia; Sierra, Isabel; Câmara, José S.; Câmara, José; Perestrelo, RosaIn recent years edible flowers emerged in gourmet cuisine, giving any dish the beauty of attractive colours, freshness, texture, and aromatic notes. Moreover, they also constitute a potential source of phytochemical compounds associated with beneficial effects on human health. In this work, the volatilomic fingerprinting of 4 different species of edible flowers [blue mallow (Malva sylvestris L.), pomegranate flower (Punica granatum L.), hibiscus (Hibiscus rosa-sinensis L.), and nasturtium (Tropaeolum majus L.)] used in gourmet dishes, was estab lished, and comparatively investigated. The volatile metabolites were extracted by solid-phase microextraction in headspace mode and identified by gas chromatography-mass spectrometry to understand the chemistry behind its attractiveness better. A total of 78 volatile metabolites, belonging to diverse chemical groups were identified. Blue mallow is mainly characterised by sesquiterpenoids (61.5% of the total volatile fraction), whereas in flowers from pomegranate, hibiscus, and nasturtium, terpenoids (56.6%), carbonyl compounds (88.0%) and organo sulfur compounds (98.0%) are the dominant chemical groups, respectively. In blue mallow flowers, τ-muurolene and valencene are the dominant volatiles, followed by α-cubebene and δ-cadinene. Pomegranate flowers are rich in furfural and linalool, while the aldehydes 2-hexenal, hexanal and 2-octenal are dominant volatile metabolites in hibiscus. Benzyl isothiocyanate, a potent antimicrobial agent, accounts for 98% of the total volatile fraction of nasturtium flowers. In addition to flavour notes, some of the identified volatile metabolites present bioactive properties, which could be explored for application in the food, pharmaceutical and cosmetic industries. The volatile metabolites profiles combined with unsupervised principal component analysis facilitated the differ entiation of the edible flowers under investigation, revealing the most related volatile metabolites of each sample, which can be used as markers for the authentication of these valuable food samples.