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- Ultrasound-assisted liquid-liquid extraction followed by ultrahigh pressure liquid chromatography for the quantification of major carotenoids in tomatoPublication . Figueira, José A.; Pereira, Jorge A.M.; Porto-Figueira, Priscilla; Câmara, José S.Lycopene and β-carotene, the main carotenoids present in different tomatoes varieties (gordal, cherry, roma and campari) of Solanum lycopersicum L. (Solanaceae), were investigated using ultrasound-assisted liquid-liquid extraction (LLUSAE) followed by ultra-high pressure liquid chromatography with PDA detection (UHPLC-PDA) analysis. Experimental parameters influencing the LLUSAE were optimized using an univariate design, resulting in a 30-min ACN/MeOH extraction by sonication of a lyophilized sample, followed by PSA/C18/MgSO4 clean-up and fast centrifugation before UPLC analysis. Using this greener methodology, high recoveries (above 97%), good linearity (r2 > 0.98) and improved sensitivity, with limits of detection and quantification of 24.0 and 80.0 ng/mL for lycopene and 3.0 and 9.9 ng/mL for β-carotene, respectively, were obtained. This sensitivity is about five times better than previously reported in literature, making LLUSAE/UHPLC-PDA a promising strategy for lycopene and β-carotene quantification in tomato and eventually in other matrices. The carotenoids studied, lycopene and β-carotene, were found at highest concentrations in the gordal tomato variety, followed by cherry, roma and campari (727.1, 342.2, 267.2 and 218.2 μg/g and 80.4, 44.0, 45.7 and 44.0 μg/g for lycopene and β-carotene, respectively). Additionally, an exponential increase of both carotenoids occurs during ripening and mainly in the skin and locular cavity of the gordal variety. These results provide further evidences of the potential of tomatoes as an interesting source of lycopene and β-carotene.
- Exploring a volatomic-based strategy for a fingerprinting approach of Vaccinium padifolium L. berries at different ripening stagesPublication . Porto-Figueira, Priscilla; Figueira, José A.; Berenguer, Pedro; Câmara, José S.The effect of ripening on the evolution of the volatomic pattern from endemic Vaccinium padifolium L. (Uveira) berries was investigated using headspace-solid phase microextraction (HS-SPME) followed by gas chromato graphy/quadrupole-mass spectrometry (GC–qMS) and multivariate statistical analysis (MVA). The most sig nificant HS-SPME parameters, namely fibre polymer, ionic strength and extraction time, were optimized in order to improve extraction efficiency. Under optimal experimental conditions (DVB/CAR/PDMS fibre coating, 40 °C, 30 min extraction time and 5 g of sample amount), a total of 72 volatiles of different functionalities were isolated and identified. Terpenes followed by higher alcohols and esters were the predominant classes in the ripening stages – green, break and ripe. Although significant differences in the volatomic profiles at the three stages were obtained, cis-β-ocimene (2.0–40.0%), trans-2-hexenol (2.4–19.4%), cis-3-hexenol (2.5.16.4%), β-myrcene (1.9–13.8%), 1-hexanol (1.7–13.6%), 2-hexenal (0.7–8.0%), 2-heptanone (0.7–7.7%), and linalool (1.9–6.1%) were the main volatile compounds identified. Higher alcohols, carboxylic acids and ketones gradually increased during ripening, whereas monoterpenes significantly decreased. These trends were dominated by the higher alcohols (1-hexanol, cis-3-hexenol, trans-2-hexenol) and monoterpenes (β-myrcene, cis-β-ocimene and trans-β ocimene). Partial least squares regression (PLSR) revealed that ethyl caprylate (1.000), trans-geraniol (0.995), ethyl isovalerate (−0.994) and benzyl carbinol (0.993) are the key variables that most contributed to the successful differentiation of Uveira berries according to ripening stage. To the best of our knowledge, no study has carried out on the volatomic composition of berries from endemic Uveira.
- Evaluation of the Health-Promoting Properties of Selected FruitsPublication . Figueira, José A.; Porto-Figueira, Priscilla; Berenguer, Cristina; Pereira, Jorge A. M.; Câmara, José S.In this study, the health-promoting benefits of different fruits grown in Madeira Island, namely lemon (Citrus limon var. eureka), tangerine (Citrus reticulata var. setubalense), pitanga (Eugenia uniflora var. red), tomato (Solanum lycopersicum var. gordal) and uva-da-serra, an endemic blueberry (Vaccinium padifolium Sm.), were investigated. The phenolic composition (total phenolics and total flavonoids content) and antioxidant capacity (assessed through ABTS and DPPH assays) were measured revealing a high phenolic potential for all fruits, except tomato, while uva-da-serra is particularly rich in flavonoids. In relation to the antioxidant capacity, the highest values were obtained for pitanga and uva-da-serra extracts. The bioactive potential was also assessed through the ability of the extracts to inhibit digestive enzymes linked to diabetes (α-amylase, α- and β glucosidases) and hypertension (angiotensin-converting enzyme, ACE). The results obtained point to a very high bioactive potential with the selected samples exhibiting very important ACE anti enzymatic capacities. A statistical analysis of the obtained data reveals a very strong correlation between ABTS and TPC, and a strong contribution of the fruit polyphenols for enzyme inhibition, and thus, presenting high antihypertensive and antidiabetic capacities. Overall, the results obtained clearly show a high bioactive potential of the selected fruits that should be further studied, in terms of specific phenolic composition. Moreover, these results strongly support the valorisation of pitanga seeds usually discarded as a waste, and uva-da-serra, an endemic and wild bush, as potential bioresources of bioactive compounds with impact in human diet.
- Tangerines cultivated on Madeira Island: a high throughput natural source of bioactive compoundsPublication . Figueira, José A.; Porto-Figueira, Priscilla; Pereira, Jorge A. M.; Câmara, José S.Tangerines (Citrus reticulata) are popular fruits worldwide, being rich in many bioactive metabolites. The setubalense variety cultivated on Madeira Island has an intense aroma easily distinguishable from other tangerines, being traditionally used to enrich several foods and beverages. Nonetheless, setubalense volatile composition has never been characterized, and we aimed to unveil the bioactive potential of peels and juices of setubalense tangerines and compare them with the murcott variety grown in Portugal mainland. Using headspace solid-phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS), we identified a total of 128 volatile organic metabolites (VOMs) in the juice and peels, with d-limonene, γ-terpinene, β-myrcene, α- and β-pinene, o-cymene, and terpinolene, the most dominant in both cultivars. In contrast, setubalense juices are richer in terpenes, many of them associated with health protection. Discriminant analysis revealed a pool of VOMs, including β-caryophyllene and E-ocimene, with bioactive properties able to differentiate among tangerines according to variety and sample type (peel vs. juice). This is the first report on the volatile composition of setubalense tangerines grown on Madeira Island revealing that its pungent aroma is constituted by secondary metabolites with specific aroma notes and health properties. This is strong evidence of the higher nutraceutical value of such fruit for the human diet.
- A fast and innovative microextraction technique, μSPEed, followed by ultrahigh performance liquid chromatography for the analysis of phenolic compounds in teasPublication . Porto-Figueira, Priscilla; Figueira, José A.; Pereira, Jorge A. M.; Câmara, José S.The objective of this study was to evaluate the efficiency of a promising solid phase microextraction technique, μSPEed, in the analysis of selected phenolic compounds from teas by ultrahigh performance liquid chromatography with photodiode array detection (μSPEed/UHPLC-PDA). The innovative μSPEed configuration uses 3-μm sorbent particles tightly packed in a disposable needle equipped with a pressure-driven valve to withdraw samples in a single direction. The system was operated by the electronic pipette eVol® and different parameters influencing the extraction efficiency, as the nature of sorbent, pH, loading and elution conditions, and solvents were optimized. The best extracting conditions were obtained by loading twice 100μL of tea samples through the PS/DVB-RP sorbent and eluting with 50μL of acidified MeOH 95%. The following chromatographic separation was carried out in an Acquity C18 BEH capillary column using a gradient of 0.1% FA and acetonitrile. The optimized μSPEed/UHPLC-PDA methodology is selective and specific and was properly validated for 8 phenolic compounds widely reported in different teas. Overall, an excellent analytical performance was obtained in the 0.2-20μg/L linear dynamic range (LDR), with very low limits of detection (LODs) and quantification (LOQs), ranging between 3.5-16.8ng/mL and 10.6-50.6ng/mL, respectively, high recoveries (89.3-103.3%), good precision (RSD<5%) and negligible matrix effect. The methodology was used to assess the target polyphenols concentration in several tea samples. Rutin and quercetin-3-glucoside were the most abundant phenolics in all tea samples analysed and, with exception of naringenin and cinnamic acid, which are present in high amounts in the investigated citric teas, remain phenolic compounds are present in trace levels.
- Current trends on microextraction by packed sorbent – fundamentals, application fields, innovative improvements and future applicationsPublication . Pereira, Jorge A. M.; Gonçalves, João; Porto-Figueira, Priscilla; Figueira, José A.; Alves, Vera; Perestrelo, Rosa; Medina, Sonia; Câmara, José S.MEPS, the acronym of microextraction by packed sorbent, is a simple, fast and user- and environmen tally-friendly miniaturization of the popular solid-phase extraction technique (SPE). In fact, it has been widely shown that MEPS can easily replace SPE for most, if not all, previous applications. It can attain this with obvious gains in sample and solvent usage, which is greatly reduced without compromising the extraction efficiency. Furthermore, MEPS can be operated with semiautomatic electronic syringes, making it very reliable and versatile, particularly to handle very low and very high sample volumes. This review will focus on the strengths and weaknesses of this technique and the different MEPS architectures commer cially available in the context of the MEPS applications reported in the last five years. Additionally, innova tive improvements will be highlighted, particularly those related with new applications and recent MEPS configurations and sorbents, such as the controlled directional flow or the innovative µSPEed variant.