Browsing by Author "Silva, A. M."
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- Drying of Maritime Plants: Effect on Antioxidant ActivityPublication . Guiné, Raquel P. F.; Barroca, M. J.; Mansinhos, I.; Silva, A. M.Salicornia and Sarcocornia belong to the same family and have similar morphological and organoleptic properties. [1]. The objective of this work was to evaluate the antioxidant activity extracts obtained from the plants in the fresh state and after being dried. Their extracts may represent a valuable source for developing novel food products (antioxidant-enriched foods), and/or table salt substitutes that satisfy the desires of consumers in terms of health benefits and sensorial acceptance. The plants (Salicornia macrostachya Moric. and Sarcocornia perennis) were collected from Portuguese salt pans, in the central region of Portugal and the aerial parts were used as raw material. The drying of plants was performed in a pilot tray drier at 40 ºC and air velocity of 1.5 ms -1 , for approximately three days. The initial moisture content was 92.30% and 84.24%, respectively, for Salicornia and Sarcocornia. The drying was carried out until reaching a final moisture content of 5%. The antioxidant activity was measured with DPPH method. Regarding the DPPH method, the results showed that the incubation time of 15 minutes is enough to measure the DPPH scavenging activity in halophyte extracts in the tested range of extract concentrations (Figure 1). However, the time defined to measure the DPPH scavenging activity was fixed at 30 minutes, since this was the common time in different laboratorial protocols. For Salicornia, the values of inhibition IC 50 were 1.09 and 1.12 mg/mL for the fresh and dried samples, respectively. For Sarcocornia, the values of IC 50 were 1.42 and 1.02 mg/mL for the fresh and dried samples, respectively. The results showed that the convective air-drying process at 40 ºC is adequate to improve the shelf life of the two halophyte plants, since the antioxidant activity was maintained or even improved as compared with the fresh samples. This might be due to a response of the plant to the stress induced by the heat and humidity conditions in the drying chamber. In this way, it was concluded that both studied halophyte plants constitute a valuable source of natural antioxidants when they are consumed as foods either in the fresh or dried states. Additionally, their extracts may represent a valuable source for developing novel antioxidant-enriched food products aimed to meet the desires of consumers who seek for health-beneficial foods.
- Evaluation of the antioxidant activity of extracts obtained form cherry seeds.Publication . Dulyanska, Y.; Cruz-Lopes, Luísa; Esteves, Bruno; Ferreira, José; Domingos, Idalina; Lima, M. J. Reis; Correia, Paula; Ferreira, Manuela; Fragata, Anabela; Barroca, Maria João; Silva, A. M.; Guiné, Raquel P. F.Annual cherry production in Portugal is around 19,000 tonnes, in an area of about 6,450 ha and covering about 11,100 farms, concentrated in some northern and central interior territories. It is also in these regions that in recent decades there has been a significant increase in farms specialized in the production of cherry, using new cultivars and new technologies in a business production model. Apart from being consumed in fresh form, cherries are used for many food preparations, like sweets, jellies or confectionary. In the plants that transform cherries, a significant amount of cherry seeds (also called cherry pits) is generated as residue or waste. The possible usage of these residues as raw material for extraction of compounds with antioxidant properties is beneficial in term of economic value as well as environmental impact. Hence, the objective of this work was to obtain extract rich in compounds with antioxidant activity from cherry seeds. The cherry seeds were obtained from a local waste management company, Nutrofertil, located in Tondela, in the district of Viseu (Portugal). They were grinded and then submitted to extraction procedures testing different operating conditions: magnetic stirrer versus ultrasound, different solvents (methanol, ethanol, water) and temperatures (from 35 ºC to 80 ºC). For the obtained extracts antioxidant activity was evaluated through spectrophotometric methods, using the DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-di-(3-ethylbenzthiazoline sulfonic acid)) radicals, and also the Ferric Reducing Antioxidant Power Assay (FRAP). All measurements were replicated at least trice, and were expressed as mg Trolox equivalents per gram (mg TE/g). The results obtained for the different experimental conditions indicated that least efficient extractions at ambient temperature were obtained with methanol using magnetic stirrer and with water using ultrasounds, for which the antioxidant activities measured by the DPPH method were 0.26 and 0.33 mg TE/g and by the ABTS method were 0.82 and 0.86 mg TE/g, respectively. Most efficient methods were water:ethanol (at 50% concentration) and water (100%), using magnetic stirrer in both cases. Highest antioxidant activity was obtained for water:ethanol by the DPPH method (0.72 mg TE/g) and for water (100%) by the ABTS method (1.25 mg TE/g). Tests with different concentrations for the aqueous solutions of ethanol and at different temperatures revealed that with increasing concentration of water the antioxidant diminished, from 0.62 to 0.27 mg TE/g at 35 ºC using the DPPH method. Additionally, the variation in temperature allowed reaching a maximum extraction of compounds with antioxidant activity at 70 ºC and decreasing thereafter. The maximum values obtained were registered at 70 ºC for all cases and were 0.74 mg TE/g for the water:ethanol 50:50 (v/v) by the DPPH method, 2.16 mg TE/g for the water:ethanol 60:40 (v/v) by the ABTS method and 3.43 mg TE/g for the water:ethanol 60:40 (v/v) by the FRAP method. The results obtained by the different methods were concordant in terms of the observed trends but giving different values of the measured antioxidant activity, which is a common characteristic observed in these types of evaluation techniques. This research allowed establishing some operational conditions that should be selected in order to maximize the extraction of compounds with antioxidant activity from cherry seeds. The use of ultrasounds was not found beneficial and the magnetic stirrer technique revealed to be more useful. Also the use of methanol was not found suitable, which is a good point given that this solvent is more pollutant and has more problems of toxicity. With respect to temperature, it was found that temperatures higher than 70 ºC are not beneficial because they induce the degradation of some bioactive compounds thus reducing the antioxidant activity of thee extracts.
- Secagem da planta Sarcocornia perennis: cinética e impacto nas propriedades físicas e nutricionaisPublication . Barroca, Maria João; Guiné, Raquel; Ressurreição, S.; Silva, A. M.; Marques, M. P. M.; Carvalho, L. A. E. B.As plantas halófitas são tolerantes à salinidade da água e, por isso, vivem em zonas costeiras, junto ao mar, como salinas, marinhas e sapais. Na biodiversidade de plantas halófitas, existem géneros comestíveis, como a 'Sarcocornia' e a 'Salicornia', também conhecidas como erva-salada, sal verde ou espargos do mar. Estas plantas, outrora consideradas ervas daninhas, actualmente são utilizadas por conceituados 'chefs' no tempero de saladas e na confecção de pratos 'gourmet'. Estudos recentes têm demonstrado que estas plantas são ricas em vitaminas, minerais, ácidos gordos polinsaturado ómega 3 e ómega 6, como o ácido alfa-linoleico e o ácido linoleico, e fitoquímicos. Estes componentes apresentam um extenso leque de funções biológicas, frequentemente relacionadas com a inibição do crescimento de células tumorais, redução do colesterol e prevenção da obesidade, devido à inibição de processos oxidativos nocivos à saúde humana. Contudo, tal como a generalidade dos vegetais, a planta 'Sarcocornia perennis' é perecível e por conseguinte é necessário recorrer a processos de conservação para prolongar a sua utilização para fins gastronómicos. A secagem é um dos métodos de preservação que permite a estabilidade dos alimentos à temperatura ambiente e diversificação do seu uso através, por exemplo, da sua incorporação noutras matrizes alimentares.
- Study of antioxidant activity in extracts from fresh and dried halophyte plantsPublication . Barroca, M. J.; Mansinhos, I. F. P.; Guiné, Raquel P. F.; Silva, A. M.Salicornia macrostachya Moric. and Sarcocornia perennis subsp. alpini belong to the same family and share morphological and organoleptic characteristics. The visually appealing in terms of freshness, color and particular taste, nutritional values and health benefits are recognized by their consumers as attributes that warrant their gourmet status. The objective of this work was to study the effect of incubation time on antioxidant capacity of these plants. Moreover, the work investigates the antioxidant activity of the extracts of the two halophyte plants and evaluates the effect of air drying the plants at 40 ºC and the procedure of concentration the extracts before evaluating the antioxidant activity, measured with DPPH method. The two halophyte plants, Salicornia macrostachya Moric. and Sarcocornia perennis subsp. alpini were collected from Portuguese salt pans, in the central region of Portugal, and the aerial parts were used as raw material. The drying of plants was performed in a pilot tray drier at 40 ºC and air velocity of 1.5 m/s, for approximately 3 days. The DPPH free radical scavenging of the methanolic extracts was analysed in extracts obtained from fresh and dried plants. The determination of the antioxidant activity was made with the DPPH radical. The results showed that, in summary, and regarding the DPPH assay, the incubation time of 15 minutes is enough to measure the DPPH scavenging activity in halophyte extracts. Furthermore, the convective air-drying process at 40 ºC showed to be an appropriate process to increase the shelf life of the halophyte plants and the antioxidant capacoty of the halophyte plants, as a response to the stress provoked by the heat and humidity drying conditions. The plant extracts showed significant antioxidant potential, with high radical scavenging activity. The extracts prepared from Salicornia macrostachya and Sarcocornia perennis had, respectively, values of IC50 equal to 1.09 and 1.42 mg/mL. However, the antioxidant activity of extracts obtained from dried plants increased much more since the IC50 decreased to around 0.6 mg/mL, regardless of the halophyte plant. Both halophytes plant are a valuable source of natural antioxidants and nutrients for use in food. Besides, their crude extracts may represent a valuable source for developing novel food products (antioxidant-enriched foods) that satisfy the desires of consumers in terms of health benefits and sensorial acceptance.
- Valorization of Halimione portulacoides as food ingredient Biological and Nutritional StudiesPublication . Pires, A.; Agreira, S.; Ressurreição, S.; Marques, J.; Guiné, Raquel P. F.; Barroca, Maria João; Silva, A. M.The prospect of global warming and freshwater reduction leads to an increase of saline and dry conditions of the land and leads to an enhanced need for salt-tolerant crops. Halimione portulacoides (sea purslane) is an halophyte plant found on coastlines and salt marches around the coasts of North Africa, South-West Asia and Europe. In Europe is one of the most productive and abundant species in salt marshes. H. portulacoides (sea purslane, “gramata branca” or “beldroega do mar” in Portuguese) is dispersed along the coast of the Iberian Peninsula. In this study, the leaves of sea purslane, collected in salt marshes of Figueira da Foz (Portugal) were characterized at nutritional and mineral composition. Total phenolic compounds (Folin Ciocalteu method) and antioxidant activity (-carotene/linoleic acid, metal chelating ability, FRAP and CUPRAC method) were also assessed in methanolic extracts obtained from the leaves. Moreover, was developed an enriched food (butter) with sea purslane powdered dried leaves and the sensorial evaluation (colour, flavour, scent, texture and overall acceptance) of the novel food was performed by a consumer panel. The butter was prepared according to standard procedure, controlling butter´s moisture content up to 16%. A portion of butter was salty with NaCl (1.0%) and the other with 0.8 % of dried leaves of sea purslane. After salting, the butter was worked vigorously to ensure even distribution of the salt or sea purslane powder. The butter enriched with H. portulacoides is presented in Figure 1. Figure 1. Butter enriched with H. portulacoides. From a nutritional point of view, sea purslane leaves may be considered as a good source of dietary fibre, protein, natural minerals such as sodium, calcium, magnesium and manganese. The intake of 100 g of fresh leaves sea purslane provides 24%, 28%, 74% and 78%, respectively, of the daily value recommended for calcium, magnesium, manganese and sodium. Due to their content in sodium, sea purslane can be viewed as a good candidate to be a food ingredient to replace salt (NaCl). On the other hand, leaves showed a high level of total phenolic compounds and a considerable antioxidant. Concerning the food sensory evaluation, butter with the incorporation of H. portulacoides had the higher scores in all organoleptic characteristics. Thus, it was verified that the use of H. portulacoides can be considered a promising salt substitute in butter and a good alternative to enhance the nutritional and sensorial characteristics of products, with additional health benefits.