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- Stability, kinetics, and application study of phycobiliprotein pigments extracted from red algae Gracilaria gracilisPublication . Pereira, Tatiana; Barroso, Sonia; Mendes, Susana; Gil, Maria M.Phycobiliprotein (PBP) pigments were extracted from red algae Gracilaria gracilis through maceration in phosphate buffer using previously optimized conditions. The stability of PBPs in the extracts was assessed by monitoring the extracts at different pHs and temperatures for 10 days. Since phycoerythrin (PE) is the main PBP present in G. gracilis, PE content was spectroscopically determined and used as a response factor. Kinetic modeling was used to describe PE degradation under different ranges of T and pH. The pigment extracts presented higher stability at pH 6.9 and −20 °C. PE was semipurified by precipitation with ammonium sulphate 65% followed by dialysis against water until a purity index of 0.7. The pigment was successfully applied as colorant in pancakes and yogurts with a pigment concentration of 0.15%. This study highlights the potential of PE pigments extracted from G. gracilis for applications in food products.
- Development, characterisation, and consumer acceptance of an innovative vegan burger with seaweedPublication . Fernandes, Wilson D.; Pinto, Filipa R.; Barroso, Sónia; Gil, Maria MWhat consumers choose when purchasing food is of most importance to promote sustainability. The consumption of more sustainable foods should be stimulated, for example, by using more sustainable ingredients and by consumer education. Therefore, an innovative and highly nutritious vegan burger with seaweed (VBS) was developed using sustainable ingredients, such as pulses—grass pea (Lathyrus sativus L.) and chickpea (Cicer arietinum L.)—and the seaweed Dulse (Palmaria palmata L.) from aquaculture. VBS was analysed for its physico-chemical and nutritional characteristics, including antioxidant activity (DPPH, TPC) and fatty acid and mineral element profiles. Shelf life and consumer acceptability were determined. The VBS was shown to be a source of protein (8.01 ± 0.14% fresh weight (FW)), fibre (5.75% FW), and mineral elements, such as P, Fe, rich in Mg, Mn, and Cu, while having low sodium content. Moreover, it presents a low sugar content. Furthermore, no antioxidant activity was detected. The pasteurised and vacuum-packed product had a shelf life of 90 days and was well accepted by consumers (64.0% acceptance). It may be concluded that an innovative VBS, nutritionally rich and with a shelf life of 90 days, was developed and well accepted by consumers, which is a good addition to a rich and diverse diet.
- Quality assessment of chilled and frozen fish: mini reviewPublication . Duarte, Ana M.; Silva, Frederica; Pinto, Filipa R.; Barroso, Sonia; Gil, Maria MFish is a very perishable food and therefore several storage strategies need to be employed to increase its shelf-life, guaranteeing its safety and quality from catch to consumption. Despite the advances in modern fish storage technologies, chilling and freezing are still the most common preservation methods used onboard. The present review aims to summarize strategies to increase the shelf-life of fresh (chilled) and frozen fish, as whole, gutted, or fillet, involving the assessment of different traditional cooling and freezing conditions of di erent fish species caught in different locations. Although there are other factors that influence the fish shelf-life, such as the fish species and the stress suffered during catch, storage time and temperature and the amount of ice are some of the most important. In addition, the way that fish is stored (whole, fillet, or gutted) also contributes to the final quality of the product. In most studies, whole chilled and frozen fish present longer shelf-life than those preserved as gutted and filleted. However, it should be noted that other factors related to the organism, capture method, and transport to the preparation/processing industry should be considered for shelf-life extension.
- Modelling fish growth with imperfect data: The case of Trachurus picturatusPublication . Neves, Ana; Vieira, Ana Rita; Sequeira, Vera; Silva, Elisabete; Silva, Frederica; Duarte, Ana Marta; Mendes, Susana; Ganhão, Rui; Assis, Carlos; Rebelo, Rui; Magalhães, Maria Filomena; Gil, Maria Manuel; Gordo, Leonel SerranoGrowth modelling is essential to inform fisheries management but is often hampered by sampling biases and imperfect data. Additional methods such as interpolating data through backcalculation may be used to account for sampling bias but are often complex and time-consuming. Here, we present an approach to improve plausibility in growth estimates when small individuals are under-sampled, based on Bayesian fitting growth models using Markov Chain Monte Carlo (MCMC) with informative priors on growth parameters. Focusing on the blue jack mackerel, Trachurus picturatus, which is an important commercial fish in the southern northeast Atlantic, this Bayesian approach was evaluated in relation to standard growth model fitting methods, using both direct readings and back-calculation data. Matched growth parameter estimates were obtained with the von Bertalanffy growth function applied to back-calculated length at age and the Bayesian fitting, using MCMC to direct age readings, with both outperforming all other methods assessed. These results indicate that Bayesian inference may be a powerful addition in growth modelling using imperfect data and should be considered further in age and growth studies, provided relevant biological information can be gathered and included in the analyses.
- Optimization of phycobiliprotein pigments extraction from red algae Gracilaria gracilis for substitution of synthetic food colorantsPublication . Pereira, Tatiana; Barroso, Sónia; Mendes, Susana; Amaral, Renata A.; Dias, Juliana R.; Baptista, Teresa; Saraiva, Jorge A.; Alves, Nuno; Gil, Maria M.The extraction of phycobiliprotein (PBP) pigments from red algae Gracilaria gracilis was optimized using maceration, ultrasound-assisted extraction (ultrasonic water bath and ultrasonic probe), high pressure-assisted extraction, and freeze-thaw. The experimental conditions, namely homogenization time (t1), buffer concentration (C), treatment time (t2), biomass: buffer ratio (R), and pressure (P), were optimized using Response Surface Methodology (RSM). The yield of phycoerythrin (PE) extracted, determined spectroscopically, was used as the response variable. Maceration was the most efficient extraction method yielding 3.6 mg PE/g biomass under the optimal conditions (t1 = t2 = 10 min; C = 0.1 M; R = 1:50). Scanning Electron Microscopy (SEM) analysis of the biomass before and after the cell disruption treatments revealed a more efficient cell wall rupture with maceration.
- Increasing biological knowledge for better management of by-catch species: Age, growth, and mortality of piper and red gurnards (Teleostei: Triglidae)Publication . Sequeira, Vera; Sousa, Inês; Neves, Ana; Vieira, Ana Rita; Silva, Elisabete; Silva, Frederica; Duarte, Ana Marta; Mendes, Susana; Ganhão, Rui; Assis, Carlos; Rebelo, Rui; Magalhães, Maria Filomena; Gil, Maria Manuel; Gordo, Leonel SerranoGurnards are a valuable by-catch of mixed demersal fisheries and are commercially important in European waters, but they are often discarded, reported under “mixed gurnards” and with incomplete biological information by species. In the present work, a total of 558 piper gurnard specimens of between 10.9 and 44.4 cm (1 to 11 years) and 425 red gurnard specimens of between 10.2 and 42.1 cm (0 to 9 years) from the northeast Atlantic (Portuguese) coast were used to study age and growth. The von Bertalanffy growth parameters for piper gurnard were estimated through the combination of whole-otolith readings and back-calculation (L∞=44.7 cm, k=0.16 yr–1 and t0=–2.781 yr). For red gurnard the same growth parameters were estimated using whole-otolith readings (L∞=40.2 cm, k=0.28 yr–1 and t0=–1.074 yr). The results indicate that the red gurnard reaches a smaller length, although it grows faster than the piper gurnard. Natural, instantaneous and fishing mortalities were estimated as well as the exploitation rate for both species. For the Portuguese coast, the red gurnard showed a higher fishing mortality and exploitation rate than the piper gurnard, raising concerns about its sustainable management.
- Seasonal study of the nutritional composition of unexploited and low commercial value fish species from the Portuguese coastPublication . Duarte, Ana M.; Silva, Frederica; Mendes, Susana; Pinto, Filipa R.; Barroso, Sonia; Silva, Elisabete; Neves, Ana; Sequeira, Vera; Magalhães, Maria Filomena; Rebelo, Rui; Assis, Carlos; Vieira, Ana Rita; Gordo, Leonel Serrano; Gil, Maria M.Target species diversification is essential for fisheries sustainability and fish market revitalization. Fish discards are a widely recognized problem resulting from fisheries worldwide, and are of major concern for all sector players, from administrations, to fishermen, and scientists. However, non-target species are seldom studied, and information on nutritional profiles and seasonal changes in nutritional properties is generally lacking. This study assessed the seasonal nutritional composition of two unexploited (Serranus cabrilla, Capros aper) and three low commercial value fish species (Trachurus picturatus, Spondyliosoma cantharus, and Trigla lyra), captured on the Portuguese coast over 1 year. Significant seasonal variations were observed in the nutritional composition of all the species studied. Moisture and ash contents varied from 70% to 81% and from 5% to 13%, respectively. The maximum fat contents were 5% for C. aper and 4% for T. picturatus, allowing to classify all studied fishes as lean. The highest protein contents were recorded for C. aper (25%) and S. cantharus (20%). The unexploited and low commercial value fish species studied were shown to be good fat and protein sources, comparable to commonly consumed species, such as cod and salmon, having a great potential to become commonly consumed fish in Portugal.
- The influence of light and culture media on the growth of the red seaweed Gracilaria gracilis (Rhodophyta, Gracilariales) under laboratory conditionsPublication . Freitas, M.V.; Correia, A.; Ribeiro, J.; Pereira, C.; Afonso, C.; Gil, M.M.; Mendes, S.; Baptista, T.; Mouga, T.
- Sabor & AlgasPublication . Gil, Maria M; Borges, Patrícia; Mendes, Susana; Mouga, TeresaO conhecimento e a exploração do mar foram definidos pelas autoridades nacionais entre as grandes linhas estratégicas para o desenvolvimento de Portugal. Por conseguinte, um amplo conjunto de oportunidades e desafios impelem todos os agentes do sistema científico e tecnológico a assumir uma postura proactiva. Deste modo, a criação de uma atividade económica forte e dedicada ao mar, assente em atividades de I&D, assume um carácter decisivo na sociedade atual. Efetivamente, uma das linhas estratégicas identificadas tem como pilar basal a procura de recursos alimentares marinhos, que possam contribuir para uma alimentação equilibrada e saudável do ser humano. Neste sentido, as algas marinhas poderão desempenhar um papel preponderante nessa área. De facto, e desde sempre, as populações ribeirinhas têm usado as algas na elaboração de remédios caseiros que depois eram usados no tratamento de diversos problemas de saúde. Essas aplicações são produto do conhecimento empírico de muitas gerações e, na maioria dos casos, desconhece-se o mecanismo de ação. No entanto, investigações recentes[1],[2],[3],[4], desenvolvidas com o objetivo de analisar os componentes e as causas que alteram o bom funcionamento do organismo humano, dão provas concretas da importância das algas marinhas na saúde humana. A realidade demonstra que a evolução científica torna cada vez mais evidente (e pertinente) a necessidade de encontrar novos caminhos na pesquisa de alimentos diferenciadores, que promovam uma dieta equilibrada e com claros benefícios para a saúde humana.
- Lipid oxidation inhibition by natural tocopherols increases the nutritional value of tuna salamiPublication . Sousa, Rita; Pedrosa, Rui; Gil, Maria M.Introduction: The quality attributes of fish products deteriorate due to the lipid oxidation during processing and storage. Tuna salami is highly susceptible to oxidation, which can precipitate health hazards and economic losses in terms of inferior product quality. Methods: The effect of adding different natural antioxidants on the lipid oxidation, colour and fatty acid profile of tuna salami after nine days of storage at 4 ºC was assessed. Three different commercial mixes of tocopherols were added during the production of the tuna salami and samples were sliced and refrigerated for 9 days. Results: The lipid oxidation increased from 0.98 to 4.03 mg of malondialdehyde/kg. The oxidation process was inhibited by DLT-100 and VIT-100; however, RNX10 did not blunt the oxidative process. VIT and dose-limiting toxicity (DLT) reduced the total unsaturated fatty acid reduction. The RNX did not prevent the reduction of the a* value. Conclusion: It was concluded that tocopherols supplementation kept the nutritional value of tuna salami mainly by lipid oxidation inhibition.