Browsing by Author "Pimentel, Filipa B."
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- Detection of Arah1 (a major peanut allergen) in food using an electrochemical gold nanoparticle-coated screen-printed immunosensorPublication . Alves, Rita C.; Pimentel, Filipa B.; Nouws, Henri P.A.; Marques, Raquel C.B.; González-García, María Begoña; Oliveira, M. Beatriz P.P.; Delerue-Matos, CristinaA gold nanoparticle-coated screen-printed carbon electrode was used as the transducer in the development of an electrochemical immunosensor for Ara h 1 (a major peanut allergen) detection in food samples. Gold nanoparticles (average diameter=32 nm) were electrochemically generated on the surface of screen-printed carbon electrodes. Two monoclonal antibodies were used in a sandwich-type immunoassay and the antibody–antigen interaction was electrochemically detected through stripping analysis of enzymatically (using alkaline phosphatase) deposited silver. The total time of the optimized immunoassay was 3 h 50 min. The developed immunosensor allowed the quantification of Ara h 1 between 12.6 and 2000 ng/ml, with a limit of detection of 3.8 ng/ml, and provided precise (RSD <8.7%) and accurate (recovery >96.6%) results. The immunosensor was successfully applied to the analysis of complex food matrices (cookies and chocolate), being able to detect Ara h 1 in samples containing 0.1% of peanut.
- Detection of the peanut allergen Ara h 6 in foodstuffs using a voltammetric biosensing approachPublication . Alves, Rita C.; Pimentel, Filipa B.; Nouws, Henri P. A.; Correr, Wagner; González-García, María Begoña; Oliveira, M. Beatriz P. P.; Delerue-Matos, CristinaA voltammetric biosensor for Ara h 6 (a peanut allergen) detection in food samples was developed. Gold nanoparticle-modified screen-printed carbon electrodes were used to develop a sandwich-type immunoassay using two-monoclonal antibodies. The antibody-antigen interaction was detected through the electrochemical detection of enzymatically deposited silver. The immunosensor presented a linear range between 1 and 100 ng/ml, as well as high precision (inter-day RSD ≤9.8 %) and accuracy (recoveries ≥96.7 %). The detection and quantification limits were 0.27 and 0.88 ng/ml, respectively. It was possible to detect small levels of Ara h 6 in complex food matrices.
- Improving bioactive compounds extractability of Amorphophallus paeoniifolius (Dennst.) NicolsonPublication . Costa, Anabela S. G.; Barreira, João C. M.; Ruas, Adilson; Vinha, Ana F.; Pimentel, Filipa B.; Alves, Rita C.; Ferreira, Isabel C. F. R.; Oliveira, M. Beatriz P. P.Elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson) is an underground, unbranched deciduous plant that produces a large tubercle (rhizome) with recognized health effects. In this study, the influence of solvent nature (water, water/etanol (1:1) and absolute ethanol) and processing type (fresh, lyophilized and boiled) on the antioxidant activity and bioactive compounds extractability of elephant foot yam was evaluated. Extracts were compared for their contents in total phenolics, flavonoids and tannins. Moreover, their antioxidant capacity was assessed by the ferric reducing antioxidant power (FRAP) and the 2,2-diphenyl-1-picrylhydrazyl radical (DPPHradical dot) scavenging capacity assays. Phenolics (154 mg GAE/L) and tannins (109 mg GAE/L) were maximized in lyophilized samples extracted with the hydroalcoholic solvent, which attained also the highest FRAP value (711 mg FSE/L). In turn, flavonoids reached the highest yields in lyophilized samples (95 mg ECE/L) extracted with pure ethanol, as well as the highest DPPHradical dot scavenging activity. These findings might have practical applications to define the best processing methodology regarding the enhancement of elephant foot yam, either for prompt consumption, as well as to develop food supplements or pharmaceutical related products.
- Improving the extraction of Ara h 6 (a peanut allergen) from a chocolatebased matrix for immunosensing detection: Influence of time, temperature and additivesPublication . Alves, Rita C.; Pimentel, Filipa B.; Nouws, Henri P.A.; Silva, Túlio H.B.; Oliveira, M. Beatriz P.P.; Delerue-Matos, CristinaThe extraction of Ara h 6 (a peanut allergen) from a complex chocolate-based food matrix was optimized by testing different temperatures, extraction times, and the influence of additives (NaCl and skimmed milk powder) in a total of 36 different conditions. Analyses were carried out using an electrochemical immunosensor. Three conditions were selected since they allowed the extraction of the highest levels of Ara h 6. These extractions were performed using 2 g of sample and 20 ml of Tris-HNO3 (pH = 8) containing: a) 0.1 M NaCl and 2 g of skimmed milk powder at 21 C for 60 min; b) 1 M NaCl and 1 g of skimmed milk powder at 21 C for 60 min; and c) 2 g of skimmed milk powder at 60 C for 60 min. Recoveries were similar or higher than 94.7%. This work highlights the importance to adjust extraction procedures regarding the target analyte and food matrix components.
- New approach for vitamin E extraction in rainbow trout flesh: Application in fish fed commercial and red seaweed-supplemented dietsPublication . Araújo, Mariana; Alves, Rita C.; Pimentel, Filipa B.; Costa, Anabela S.G.; Fernandes, Telmo J.R.; Valente, Luísa M.P.; Rema, Paulo; Oliveira, M. Beatriz P.P.A vitamin E extraction method for rainbow trout flesh was optimized, validated, and applied in fish fed commercial and Gracilaria vermiculophylla-supplemented diets. Five extraction methods were compared. Vitamers were analyzed by HPLC/DAD/fluorescence. A solid-liquid extraction with n-hexane, which showed the best performance, was optimized and validated. Among the eight vitamers, only α- and γ-tocopherol were detected in muscle samples. The final method showed good linearity (>0.999), intra- (<3.1%) and inter-day precision (<2.6%), and recoveries (>96%). Detection and quantification limits were 39.9 and 121.0 ng/g of muscle, for α-tocopherol, and 111.4 ng/g and 337.6 ng/g, for γ-tocopherol, respectively. Compared to the control group, the dietary inclusion of 5% G. vermiculophylla resulted in a slight reduction of lipids in muscle and, consequently, of α- and γ-tocopherol. Nevertheless, vitamin E profile in lipids was maintained. In general, the results may be explained by the lower vitamin E level in seaweed-containing diet. Practical Applications: Based on the validation results and the low solvent consumption, the developed method can be used to analyze vitamin E in rainbow trout. The results of this work are also a valuable information source for fish feed industries and aquaculture producers, which can focus on improving seaweed inclusion in feeds as a source of vitamin E in fish muscle and, therefore, take full advantage of all bioactive components with an important role in fish health and flesh quality.
- Nutritional composition of low protein and phenylalanine-restricted dishes prepared for phenylketonuric patientsPublication . Pimentel, Filipa B.; Alves, Rita C.; Costa, Anabela S. G.; Fernandes, Telmo J. R.; Torres, Duarte; Almeida, Manuela F.; Oliveira, M. Beatriz P. P.Nutritional management is essential for Phenylketonuria (PKU) treatment, consisting in a semi-synthetic and low phenylalanine (Phe) diet, which includes strictly controlled amounts of low protein natural foods (essentially fruits and vegetables) supplemented with Phe-free protein substitutes and dietetic low-protein products. PKU diet has to be carefully planned, providing the best ingredient combinations, so that patients can achieve good metabolic control and an adequate nutritional status. Hereupon, it is mandatory to know the detailed composition of natural and/or cooked foodstuffs prepared specifically for these patients. We intended to evaluate sixteen dishes specifically prepared for PKU patients, regarding the nutritional composition, Phe and tyrosine (Tyr) contents, fatty acids profile, and vitamins E and B12 amounts. The nutritional composition of the cooked samples was 15.5–92.0 g/100 g, for moisture; 0.7–3.2 g/100 g, for protein; 0.1–25.0 g/100 g, for total fat; and 5.0–62.0 g/100 g, for total carbohydrates. Fatty acids profile and vitamin E amount reflected the type of fat used. All samples were poor in vitamin B12 (0.3–0.8 μg/100 g). Boiled rice presented the highest Phe content: 50.3 mg/g of protein. These data allow a more accurate calculation of the diet portions to be ingested by the patients according to their individual tolerance.
- Phenolic compounds from olive mill wastes: Health effects, analytical approach and application as food antioxidantsPublication . Araújo, Mariana; Pimentel, Filipa B.; Alves, Rita C.; Oliveira, M. Beatriz P.P.Background Over the years, food industry wastes have been the focus of a growing interest due to their content in high added-value compounds. A good example are the olive oil by-products (OOBP), which retain a great amount of phenolic compounds during olive oil production. Their structure and biological properties justify their potential use as antioxidants in other food products. The efficient recovery of phenolic compounds has been extensively studied and optimized in order to maximize their reintroduction in the food chain and contribute to a higher valorization and better management of wastes from olive oil industry. Scope and approach This paper reviews the most representative phenolic compounds described in OOBP and their biological properties. New extraction procedures to efficiently recover these compounds and the most advanced chromatographic techniques that have been used for a better understanding of the phenolic profile of these complex matrices are also referred. Finally, this paper reports the main applications of OOBP, with emphasis on their phenolic content as natural antioxidants for food applications. Key findings and conclusions Besides their antioxidant activity, phenolic compounds from OOBP have also shown antimicrobial and antitumoral properties. Their application as food antioxidants requires new extraction techniques, including the use of non-toxic solvents and, in a pilot scale, the use of filters and adsorbent resins. The inclusion of phenolic compounds from OOBP in some food matrices have improved not only their antioxidant capacity but also their sensory attributes.
- Phenylketonuria: Protein content and amino acids profile of dishes for phenylketonuric patients. The relevance of phenylalaninePublication . Pimentel, Filipa B.; Alves, Rita C.; Costa, Anabela S. G.; Torres, Duarte; Almeida, Manuela F.; Oliveira, M. Beatriz P. P.Phenylketonuria is an inborn error of metabolism, involving, in most cases, a deficient activity of phenylalanine hydroxylase. Neonatal diagnosis and a prompt special diet (low phenylalanine and natural-protein restricted diets) are essential to the treatment. The lack of data concerning phenylalanine contents of processed foodstuffs is an additional limitation for an already very restrictive diet. Our goals were to quantify protein (Kjeldahl method) and amino acid (18) content (HPLC/fluorescence) in 16 dishes specifically conceived for phenylketonuric patients, and compare the most relevant results with those of several international food composition databases. As might be expected, all the meals contained low protein levels (0.67–3.15 g/100 g) with the highest ones occurring in boiled rice and potatoes. These foods also contained the highest amounts of phenylalanine (158.51 and 62.65 mg/100 g, respectively). In contrast to the other amino acids, it was possible to predict phenylalanine content based on protein alone. Slight deviations were observed when comparing results with the different food composition databases.
- Targeting specific nutrient deficiencies in proteinrestricted diets: some practical facts in PKU dietary managementPublication . Pimentel, Filipa B.; Alves, Rita C.; Oliva-Teles, M. Teresa; Costa, Anabela S. G.; Fernandes, Telmo J. R.; Almeida, Manuela F.; Torres, Duarte; Delerue-Matos, Cristina; Oliveira, M. Beatriz P. P.Among aminoacidopathies, phenylketonuria (PKU) is the most prevalent one. Early diagnosis in the neonatal period with a prompt nutritional therapy (low natural-protein and phenylalanine diet, supplemented with phenylalanine-free amino acid mixtures and special low-protein foods) remains the mainstay of the treatment. Data considering nutrient contents of cooked dishes is lacking. In this study, fourteen dishes specifically prepared for PKU individuals were analysed, regarding the lipid profile and iron and zinc contents. These dishes are poor sources of essential nutrients like Fe, Zn or n-3 fatty acids, reinforcing the need for adequate supplementation to cover individual patients’ needs. This study can contribute to a more accurate adjustment of PKU diets and supplementation in order to prevent eventual nutritional deficiencies. This study contributes to a better understanding of nutrient intake from PKU patients’ meals, showing the need for dietary supplementation.
- The phytochemical and bioactivity profiles of wild Calluna vulgaris L. flowersPublication . Rodrigues, Francisca; Moreira, Teresa; Pinto, Diana; Pimentel, Filipa B.; Costa, Anabela S.G.; Nunes, M. Antónia; Gonçalves Albuquerque, Tânia; S. Costa, Helena; Palmeira-de-Oliveira, Ana; Oliveira, Ana Isabel; Sut, Stefania; Dall'Acqua, Stefano; Oliveira, M. Beatriz P.P.The nutritional composition of Calluna vulgaris flowers as well as the phytochemical profile, antioxidant (DPPH and FRAP assays), antimicrobial and cytotoxic (in human immortalized non-tumorigenic keratinocyte and fibroblasts) activities of aqueous, hydroalcoholic and ethanolic extracts were evaluated. A high content of fiber and carbohydrates (75%) and the prevalence of α-tocopherol as vitamer deserves attention. Linolenic (35%), linoleic (27%) and palmitic (21%) acids were the most abundant fatty acids. Qualitative and quantitative analysis by LC-MS and 1NMR indicated high levels of quercetin, kaempferol and myricetin derivatives as well as procyanidins. The hydro-alcoholic extract displayed the highest antioxidant activity and total phenolics (TPC) and flavonoid contents (TFC). No adverse effects on cells were observed until a concentration of 100 μg/mL and a good antimicrobial activity was reported against S. epidermidis and S. aureus with the hydro-alcoholic extract. The data obtained demonstrated that wild plants like heather, although not being a common nutritional reference, can be used in an alimentary base as a source of bioactive compounds, namely antioxidants.