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- Effect of peel and seed removal on the nutritional value and antioxidant activity of tomato (Lycopersicon esculentum L.) fruitsPublication . Vinha, Ana F.; Alves, Rita C.; Barreira, Sérgio V. P.; Castro, Ana; Costa, Anabela S. G.; Oliveira, M. Beatriz P. P.The effect of peel and seed removal, two commonly practiced procedures either at home or by the processing industry, on the physicochemical properties, bioactive compounds contents and antioxidant capacity of tomato fruits of four typical Portuguese cultivars (cereja, chucha, rama and redondo) were appraised. Both procedures caused significant nutritional and antioxidant activity losses in fruits of every cultivar. In general, peeling was more detrimental, since it caused a higher decrease in lycopene, bcarotene, ascorbic acid and phenolics contents (averages of 71%, 50%, 14%, and 32%, respectively) and significantly lowered the antioxidant capacity of the fruits (8% and 10%, using DPPH. and b-carotene linoleate model assays, correspondingly). Although seeds removal favored the increase of both color and sweetness, some bioactive compounds (11% of carotenoids and 24% of phenolics) as well as antioxidant capacity (5%) were loss. The studied cultivars were differently influenced by these procedures. The fruits most affected by peeling were those from redondo cultivar (-66% lycopene, -44% b-carotene, -26% ascorbic acid and -38% phenolics). Seeds removal, in turn, was more injurious for cereja tomatoes (-10% lycopene, -38% b-carotene, -25% ascorbic acid and -63% phenolics). Comparatively with the remaining ones, the rama fruits were less affected by the trimming procedures.
- Total antioxidant capacity of plant infusions: Assessment using electrochemical DNA-based biosensor and spectrophotometric methodsPublication . Barroso, M. Fátima; Ramalhosa, Maria João; Alves, Rita C.; Dias, Alexandra; Soares, Cristina M. D.; Oliva-Teles, M. Teresa; Delerue-Matos, CristinaNine plant infusions were assessed in terms of their polyphenolic compounds and antioxidant capacity properties by performing a “battery” of assays. Bioactive compounds (total phenolic and flavonoid content) were measured using spectrophotometric procedures and the total antioxidant capacity was determined by DPPHradical dot-RSA, FRAP and DNA-based biosensor against the reactive oxygen species: HOradical dot and H2O2. Although the optical methods are based on the donation of hydrogen or electrons between antioxidants and radicals, the DNA-based biosensor intends to simulate an in vivo assay by exposing DNA layer to biological ROS and antioxidants. In general, green and black tea showed higher polyphenolic content and antioxidant capacity evaluated by the described methods. All the analysed plant beverages showed to be a good source of bioactive compounds, particularly the green and black tea, peppermint and senna.
- 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.
- Impact of boiling on phytochemicals and antioxidant activity of green vegetables consumed in the Mediterranean dietPublication . Vinha, Ana F.; Alves, Rita C.; Barreira, Sérgio V. P.; Costa, Anabela S. G.; Oliveira, M. Beatriz P. P.The effect of boiling (10 minutes) on eleven green vegetables frequently consumed in the Mediterranean diet was evaluated. For that, some physicochemical parameters and the contents of vitamin C, phenolics and carotenoids, as well as the antioxidant activity, were determined in raw and boiled samples. The raw vegetables analysed in this study were good sources of vitamin C, carotenoids and phenolic compounds, with contents ranging from 10.6 to 255.1 mg/100 g, 0.03 to 3.29 mg/100 g and 202.9 to 1010.7 mg/100 g, respectively. Boiling promoted losses in different extensions considering both the different bioactive compounds and the distinct vegetables analysed. Contrary to phenolics (more resistant), vitamin C was the most affected compound. Boiling also originated significant losses in the antioxidant activity of the vegetables. Considering all the parameters analysed, the vegetables most affected by boiling were broccoli and lettuce. The least affected ones were collard and tronchuda cabbage.
- 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.
- How functional foods endure throughout the shelf storage? Effects of packing materials and formulation on the quality parameters and bioactivity of smoothiesPublication . Nunes, M. Antónia; Costa, Anabela S. G.; Barreira, João C. M.; Vinha, Ana F.; Alves, Rita C.; Rocha, Ada; Oliveira, M. Beatriz P. P.Smoothies are blended beverages that could contain fruit pulp, fruit juice, vegetables, yoghurt, milk, or honey. These beverages are typical examples of the food industry reply to the increase awareness of consumers for healthier foods with simple ingredients and clean labels. As emerging products, different profiling studies are needed to ensure their claimed properties. Accordingly, different physicochemical parameters, bioactive compounds, as well as the antioxidant activity, were assessed in commercial smoothies along different shelf storage periods. ANOVA, HCA and LDA statistical tools were used to allow a suitable comprehension of the obtained results. Some significant differences were found at initial time, which might be associated to smoothies’ composition. On the other hand, the physicochemical and chromatic parameters were stable during the shelf storage, while the content in bioactive compounds and the antioxidant activity indicators were significantly affected (independently of the applied thermal treatment). Nevertheless, none of the assayed formulations or packing types showed to be more susceptible to undergone specifically relevant changes during shelf storage. Overall, the results advice in favor of an earlier consumption of these products (far from the expiring date) in order to obtain the desired health effects.
- 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.
- 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.
- Organic versus conventional tomatoes: Influence on physicochemical parameters, bioactive compounds and sensorial attributesPublication . Vinha, Ana F.; Barreira, Sérgio V. P.; Costa, Anabela S. G.; Alves, Rita C.; Oliveira, M. Beatriz P. P.The effect of organic and conventional agricultural systems on the physicochemical parameters, bioactive compounds content, and sensorial attributes of tomatoes (‘‘Redondo’’ cultivar) was studied. The influence on phytochemicals distribution among peel, pulp and seeds was also accessed. Organic tomatoes were richer in lycopene (+20%), vitamin C (+30%), total phenolics (+24%) and flavonoids (+21%) and had higher (+6%) in vitro antioxidant activity. In the conventional fruits, lycopene was mainly concentrated in the pulp, whereas in the organic ones, the peel and seeds contained high levels of bioactive compounds. Only the phenolic compounds had a similar distribution among the different fractions of both types of tomatoes. Furthermore, a sensorial analysis indicated that organic farming improved the gustative properties of this tomato cultivar.
- Monomeric and oligomeric flavan-3-ols and antioxidant activity of leaves from different Laurus sp.Publication . Vinha, Ana F.; Guido, Luís F.; Costa, Anabela S. G.; Alves, Rita C.; Oliveira, M. Beatriz P. P.The phenolic profile and antioxidant activity of three endemic Laurus sp. from Portugal were analysed. Dried leaves of L. nobilis L., L. azorica (Seub.) Franco, and L. novocanariensis Rivas Mart., Lousã, Fern. Prieto, E. Días, J. C. Costa & C. Aguiar, collected in the mainland and in the Azores and Madeira archipelagos, respectively, were used to prepare different extracts (aqueous, ethanolic and hydroalcoholic). They were studied regarding their DPPH˙ scavenging activity, total phenolic and flavonoid contents, and the main phenolic compounds were identified by HPLC-DAD-ESI-MS/MS. Total flavonoid contents were 30.1, 46.3, and 36.7 mg of epicatechin equivalents per g of sample (dry weight) for L. nobilis, L. azorica and L. novocanariensis, respectively. Epicatechin was the major compound, representing ∼12.1% of total flavan-3-ols in L. nobilis, ∼25.6% in L. azorica, and ∼19.9% in L. novocanariensis. Although all samples presented a similar phenolic profile, significant differences were observed in their total contents and antioxidant activity.
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