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- 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.
- 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.
- Adding value to bycatch fish species captured in the Portuguese coast—development of new food productsPublication . Silva, Frederica; Duarte, Ana M.; Mendes, Susana; Borges, Patrícia; Magalhães, Elisabete; Pinto, Filipa R.; Barroso, Sonia; Neves, Ana; Sequeira, Vera; Vieira, Ana Rita; Magalhães, Maria Filomena; Rebelo, Rui; Assis, Carlos; Gordo, Leonel SerranoWe live in a world of limited biological resources and ecosystems, which are essential to feed people. Consequently, diversifying target species and considering full exploitation are essential for fishery sustainability. The present study focuses on the valorization of three low commercial value fish species (blue jack mackerel, Trachurus picturatus; black seabream, Spondyliosoma cantharus; and piper gurnard, Trigla lyra) and of two unexploited species (comber, Serranus cabrilla and boarfish, Capros aper) through the development of marine-based food products with added value. A preliminary inquiry with 155 consumers from Região de Lisboa e Vale do Tejo (Center of Portugal) was conducted to assess fish consumption, the applicability of fish product innovation, and the importance of valorizing discarded fish. Five products (black seabream ceviche, smoked blue jack mackerel pâté, dehydrated piper gurnard, fried boarfish, and comber pastries) were developed and investigated for their sensory characteristics and consumer liking by hedonic tests to 90 consumers. The most important descriptors were identified for each product (texture, flavor, color, and appearance). Comber pastries had the highest purchase intention (88%), followed by black seabream ceviche (85%) and blue jack mackerel pâté (76%). Sensory evaluations showed a clear tendency of consumers to accept reformulated products, with the introduction of the low-value and unexploited species under study.
- Negative impact on the reproductive potential of blue jack mackerel Trachurus picturatus by Kudoa infection of the ovaryPublication . Neves, A.; Gordo, I.; Sequeira, V.; Vieira, A.R.; Silva, E.; Silva, F.; Duarte, A.M.; Mendes, S.; Ganhão, R.; Peleteiro, M.C.; Assis, C.; Rebelo, R.; Magalhães, M.F.; Gil, M. M.; Gordo, L.S.Reproduction of Trachurus picturatus off the western Portuguese coast was studied over 1 yr. During histological analyses, the presence of Kudoa sp. was detected in advanced vitellogenic oocytes. Kudoa infections are known to cause economic loss through the induction of postmortem liquefaction of fish muscles, but ovarian infection as reported in this study will seriously affect the reproductive potential of the species and thus impact fisheries productivity. Only females showed gonad infection which led to total degradation of advanced vitellogenic oocytes. No macroscopic, somatic or condition indices revealed differences between infected and uninfected females, rendering this infection event a concealed suppression of reproduction.
- Macroalgas para Aplicações Alimentares: Ingredientes Naturais na Prevenção da Diabetes Tipo 2Publication . Duarte, Ana Marta Cardoso; Silva, Maria Manuel Gil de Figueiredo Leitão e; Mendes, Susana Luísa da Custódia Machado; Guarino, Maria Pedro SucenaA diabetes mellitus corresponde a uma patologia caraterizada por hiperglicémia crónica, sendo a diabetes mellitus tipo 2 (DM2) relacionada com a deterioração progressiva das funções das células β pancreáticas. A nutrição é considerada fundamental no controlo da DM2, com evidências crescentes dos benefícios das macroalgas, pelo seu teor de compostos antioxidantes (ação inibitória sobre enzimas do metabolismo de glícidos) e riqueza nutricional em macronutrientes torna-as um recurso alimentar de excelência. O presente estudo visa a avaliação da atividade inibitória das enzimas α-amilase, α-glucosidase e dipeptidil-peptidase-4 (DPP4) pelo extrato da macroalga Fucus spiralis, bem como a avaliação da sua capacidade antioxidante, com posterior validação em matriz alimentar como caso de estudo. As condições de extração dos compostos bioativos, por vortex, banho de ultrassons, homogeneizador e sonicador, foram otimizadas utilizando a metodologia de superfície de resposta (MSR) usando o desenho central rotacional (CRD) com base em três variáveis independentes (tempo de extração, biomassa e solvente), tendo como resposta: IC50 para DPPH; μmol EAA/g para FRAP; mg EAG/g para TPC. Posteriormente, as condições ótimas de extração selecionadas, tiveram em conta a maior extração de antioxidantes, requisitos de sustentabilidade ambiental e segurança alimentar (ausência de solventes orgânicos, recurso de materiais e tempo reduzido). A extração de antioxidantes otimizada foi obtida recorrendo ao homogeneizador, com as condições de extração: solvente de 50 ml etanol/100 ml com 26 % biomassa, durante 300 segundos. O extrato otimizado revelou capacidade antioxidante, segundo os métodos estudados (FRAP = 134,560 ± 91,738 mol EAA/g extrato; TPC = 271,310 ± 12,710 mg EAG/g extrato), bem como inibição da α-amilase (IC50 = 0,018 (0,011 – 0,028) mg/ml), α-glucosidase (IC50 = 0,0004 (5,485 x 10-7 – 0,003) mg/ml) e DPP4 (IC50 = 0,003 (0,002 – 0,004) mg/ml). O potencial de inibição enzimático, avaliado por metodologia in vitro com métodos espectrofotométricos, revelou-se superior à acarbose, inibidor da α-amilase e α-glucosidase, alcançando-se inibições semelhantes entre a DPP4 e a diprotina A. Como caso de estudo, desenvolveu-se e caracterizou-se um puré de maçã com adição de extrato de Fucus spiralis. Os resultados demonstraram que o produto desenvolvido revelou capacidade antioxidante (FRAP = 239,062 ± 42,651 mol EAA/g extrato; TPC = 303,880 ± 14,570 mg EAG/g extrato), bem como inibição enzimática (IC50 α-amilase =0,027 (0,023 -0,032) mg/ml; IC50 α-glucosidase = 0,020 (0,018 – 0,023) mg/ml; e IC50 mínimo de 0,010 (0,004 – 0,021) mg/ml para a DPP4). A avaliação química do puré revelou teores de humidade >80 %, aumento do pH com o tempo, teores de sacarose >15 g/ 100 g e índice de escurecimento, ao fim de 8 dias, superior a 90 % nas amostras de puré e de 77 % num produto comercial semelhante, indicando elevada atividade enzimática. Por último, o puré foi avaliado por uma painel sensorial semitreinado, verificando-se boa aceitabilidade indicando potencial do produto desenvolvido no mercado. Foram inquiridos 105 diabéticos tipo 2, visando a avaliação do seu perfil de consumo, bem como a sua facilidade em interpretar rótulos alimentares permitindo conhecer a potencialidade do puré de maçã com extrato de alga desenvolvido, como caso de estudo. A amostragem é representada por mulheres (67,6 %, n = 71) entre os 56 e 65 anos (27,6 %, n = 29), do distrito de Lisboa (63,8 %, n = 67), com ensino básico ou inferior (52,4 %, n = 55) e com consumo maioritário de cereais e derivados (31,4 %, n = 33). Verificou-se que o consumo de algas é unicamente explicado pela idade (Fisher = 13,488, p-value = 0,006) e habilitações académicas (Fisher = 10,329, p-value = 0,005), instigando a necessidade de desenvolvimento de estratégias de promoção dos benefícios do consumo de algas na restante população. O extrato de Fucus spiralis demonstrou elevada capacidade antioxidante e de inibição de enzimas alvo na prevenção e controlo da patologia, tornando-se promissor na prevenção da DM2.
- Seasonal sensory evaluation of low commercial value or unexploited fish species from the Portuguese coastPublication . Silva, Frederica; Duarte, Ana M.; Mendes, Susana; Magalhães, Elisabete; Pinto, Filipa R.; Barroso, Sonia; Neves, Ana; Sequeira, Vera; Vieira, Ana Rita; Gordo, Leonel; Gil, Maria ManuelOverfishing is increasing over time, and according to FAO (Food and Agriculture Organization), about one third of the world’s fish stocks are now overfished. Thus, diversifying the target species is essential for fisheries sustainability contributing to improve resource-effcient processes. Non-target species can be valuable resources for the development of new food products. However, those species are scarcely studied, and it is of high importance to trace their seasonal sensory profile as a first step towards their valorisation. Therefore, in this study, seasonal influence on sensory properties of five low commercial value or unexploited fish species, namely Trachurus picturatus (blue jack mackerel), Spondyliosoma cantharus (black seabream), Trigla lyra (piper gurnard), Serranus cabrilla (comber) and Capros aper (boarfish), was assessed in order to identify the most favourable season for catching each species. Fish samples were assessed by a panel of 16 semi-trained assessors for sensory attributes previously identified. The evaluation takes place every 2 months. Statistical differences were reported between attributes and seasons for all species, except for T. lyra, which did not present any di erence in its sensory attributes throughout the year.
- Enhancing knowledge on low-value fishing species: the distinct reproductive strategy of two gurnard speciesPublication . Neves, Ana; Sousa, Inês; Sequeira, Vera; 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 SerranoThe depletion and overexploitation of several fish stock demands for a valorisation of non-target and discarded species. Nonetheless, such species are often poorly studied, and information on their biological parameters must be gathered for effective population management. For 1 year, the reproductive strategy of the piper gurnard Trigla lyra and the red gurnard Chelidonichthys cuculus was studied by monthly samples obtained from commercial boats operating on western Portuguese coast. Both species showed a biased sex ratio towards females, especially for larger length classes. Length at first maturity could be estimated only for red gurnard (22.1 and 19.9 cm for females and males, respectively) because all piper gurnard individuals caught were mature. Piper gurnard showed determinate fecundity and a short spawning season, from November to February with a peak in January, whereas red gurnard showed indeterminate fecundity and a wide spawning season, from late December to May. The relative annual fecundity estimated for red gurnard (1893 ± 728 oocytes x g-1 eviscerated weight [EW]) was higher than the one estimated for piper gurnard (1018 ± 250 oocytes x g-1 EW). Although important information for understanding the species dynamics is presented in this study, additional information on other life-history parameters and of species landings is required.
- CATA vs. FCP for a rapid descriptive analysis in sensory characterization of fishPublication . Silva, Frederica; Duarte, Ana M.; Mendes, Susana; Pinto, Filipa R.; Barroso, Sonia; Ganhão, Rui; Gil, Maria M.Storing non-marketable fish aboard fishing vessels takes up valuable storage space and, consequently, it is usually discarded. Therefore, the strategy to minimize the amount of discarded fish and boost the fishing economy should entail measures to turn unexploited species into marketable fish. The use of sensory descriptive analysis is usually the first step in the characterization of foods and assess their baseline appeal to the final consumer. In this study, the sensory characterization of five unexploited fish species was conducted, using a semi-trained panel, with the objective of establishing the appeal and marketability of these species. Check-all-that-apply (CATA) and Free Choice Profiling (FCP) were used to obtain descriptive attributes. Correspondence Analysis (CA) was used to examine CATA data and to compare both sensory methods, while Principal Component Analysis (PCA) was used for FCP data analysis. The results obtained with CATA method allowed to differentiate species by appearance, odor and flavor, while appearance and odor were statistically significant descriptors in FCP. CATA method was found to be more suitable to discriminate fish species, presenting a higher discriminatory power than FCP.