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- Response surface methodology in the optimization of extraction conditions for Gracilaria gracilis extracts for use in thermoplastic food coatingsPublication . Reboleira, João; Andrade, Mariana A.; Sanches-Silva, Ana; Ganhão, Rui; Mendes, Susana; Vilarinho, Fernanda; Félix, Rafael; Pinheiro, Joaquina; Bernardino, Susana M.Incorporation of antioxidant agents in edible films and packages often relies in the usage of essential oils and other concentrated hydrophobic liquids, with reliable increases in antimicrobial and antioxidant activities of the overall composite, and consequent improvements in product shelf life. These oils are often obtained from plant sources and the usage of organic solvents in their extraction has been criticized as to whether it constitutes a health hazard for consumers [1, 2, 3]. The use of water-soluble antioxidant agents is less common, due to lower activities and extraction yields. As such, using commonly available seaweeds as the source for both the main polymers and the supplementing antioxidant/antimicrobial agents in bioactive films can potentially reduce production costs and create a safer, more sustainable product [1]. Hydroethanolic extracts of commercially available red macroalgae Gracilaria gracilis were evaluated for their antioxidant potential and phenolic content, as part of the preliminary assays for the selection of algal biomass for the enrichment of thermoplastic films. The extracts were obtained through use of solid-liquid extractions, over which yield, DPPH radical reduction capacity, total phenolic content, and FRAP activity assays were measured [4, 5]. Solid to liquid ratio (SLR), extraction time, and ethanol to water ratio were selected as independent variables with experimental ranges and configurations obtained using a Box-Behnken design with three factors, resulting in 15 experimental conditions. Extraction duplicates were used [4]. Response surface methodology was then used to estimate the effect of each extraction condition on the tested bioactivities. Bioactivities were significantly (p<0.05) and positively affected by the presence of ethanol in the extraction solvent, while extraction yield was reduced. Lower solid to liquid ratios (higher solvent proportions) resulted in higher yields, but had no significant (p<0.05) impact on bioactivities. Time was not a relevant factor in any of the measured variables, and as such will be minimized in any further work. 100% ethanol with minimum extraction time (10 minutes) and 1g to 5mL SLR maximize antioxidant activities per gram of dry extract. Maximum ethanolic yields were obtained with a theoretical extraction of 100 minutes and a 1g to 25mL SLR. Aqueous extractions displayed similar results in terms of optimum conditions, but with overall lower bioactivities and higher yields, very likely due to high amounts of soluble polysaccharides. While the high antioxidant activities from the ethanolic extracts encourage the selection of this solvent for extraction of bioactives, low yields may make them later unfeasible. Future studies over the compatibility of these extracts in the polymeric matrix of the films, as well as further optimization of the extraction process will be necessary before the definitive choice for bioactive origin and processing is made.
- 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.
- Novel active food packaging films based on whey protein incorporated with seaweed extract: development, characterization, and application in fresh poultry meatPublication . Andrade, Mariana A.; Barbosa, Cássia H.; Souza, Victor G. L.; Coelhoso, Isabel M.; Reboleira, João; Bernardino, Susana; Ganhão, Rui; Mendes, Susana; Fernando, Ana Luisa; Vilarinho, Fernanda; Silva, Ana Sanches; Ramos, FernandoAlgae and seaweeds are used in cookery since the beginnings of human civilization, particularly in several Asian cultures. Phenolic compounds are secondary metabolites produced by aquatic and terrestrial plants for their natural defense against external stimuli, which possess powerful antimicrobial and antioxidant properties that can be very important for the food industry. The main objective of this study was to develop a whey protein concentrate active coating, incorporated with a Fucus vesiculosus extract in order to delay the lipid oxidation of chicken breasts. Ten hydroethanolic extracts from F. vesiculosus were obtained and their antioxidant capacity was evaluated through two antioxidant activity assays: the DPPH radical scavenging activity and -carotene leaching assay. The total content in phenolics compounds was also determined by Folin-Ciocalteu method. The chosen extract was the one obtained from the freeze-dried F. vesiculosus using 75% (v/v) ethanol as extraction solvent. The extract was successfully incorporated into a whey protein film and successfully strengthened the thickness, tensile strength, and elastic modulus. The active film also was able to inhibit the chicken breasts lipid oxidation for 25 days of storage.
- Characterization of nutritional, physicochemical, and phytochemical composition and antioxidant capacity of three strawberry “Fragaria X ananassa Duch.” Cultivars (“Primoris”, “Endurance”, and “Portola”) from western region of PortugalPublication . Ganhão, Rui; Pinheiro, Joaquina; Tino, Clara; Faria, Hugo; Gil, Maria MIn this study, nutritional composition (protein, lipids, carbohydrates, ash, and moisture), physicochemical properties (soluble solid content, titratable acidity, texture and instrumental colour on surface, and internal section), phytochemicals (total phenolic content and anthocyanin content), and antioxidant capacity (DPPH—2,2'-diphenyl-1-picrylhydrazyl radical scavenging capacity and ferric-reducing antioxidant power) of three strawberry (Fragaria X ananassa Duch.) cultivars (cv. “Primoris”, cv. “Endurance”, and cv. “Portola”) produced in the western region of Portugal (Caldas da Rainha) were evaluated. From the obtained, results no significant differences (P > 0.05) in nutritional composition were detected in all of the cultivars; with the exception of lower protein content observed in cv. “Portola” (0.57 g/100 g +- 0.04; P < 0.05). Regarding the a* value of whole strawberry fruits, no significant differences (P > 0.05) were found in any of the cultivars, which revealed a similar redness. The cv. “Endurance” revealed the highest bioactivity content compared to the other cultivars. Overall, these results provide important information about the high quality of strawberry produced in the western region of Portugal and may be used as a tool for adding value to a functional food in the Mediterranean diet due to the phytochemical composition and nutritional value of strawberry fruits.
- Desenvolvimento de Paté de lapa, Patella spp. com adição de medronho, Arbutus unedoPublication . Ganhão, R.; Rodrigues, S.; Maranhão, P.Limpets Patella are gastropods molluscs with an increasing use in human food, being a popular food too much appreciated in several coastal regions of Portugal. According to the chain of seafood, the consumption of fishery products rich in polyunsaturated fatty acids, has replaced the products of terrestrial animals through the filleted products, restructured products and precooked products. Food oxidation is the most important cause in the deterioration of nutritional and sensory quality of fish products. So, in recent years, there has been an increasing utilization of natural antioxidants of vegetable origin (fruits and vegetables) in substitution of the synthetic antioxidants in the preparation of restructured products of animal origin (burgers, sausages and pâtés). In addition to this antioxidant effect, there is a beneficial relationship between the consumption of fruit and vegetable rich in phenolic compounds in the prevention of certain diseases. So, this project intends to produce and characterize physical-chemical properties, sensorial analysis and microbiological analysis in one pâté elaborate with limpets and with addition of arbutus wild fruit, as well as valorisation of these raw materials to providing the nutritional/functional and economic value to the development of an innovative product (pâté). Furthermore, we evaluated the oxidative stability of pâté in refrigeration for 90 days and its acceptability. Thus, we produced three types of innovative pâtés: I) Patella spp. pâté with BHT (PCON), II) Patella spp. pâté with 3% of the Arbutus unedo (PAU3) and III) Patella spp. pâté with 6% of the Arbutus unedo (PAU6). The results of the evaluation of oxidative stability (PAU6>PAU3>PCON) confirm the high performance of the Arbutus unedo extract rich in phenolic compounds as effective inhibitor in lipid oxidation of the Patella spp. pâté and with good sensory acceptability.
- 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.
- Motivation and preferences of Portuguese consumers’ towards sea urchin roePublication . Lourenço, Sílvia; Mendes, Susana; Raposo, Andreia; Santos, Pedro M.; Gomes, Ana S.; Ganhão, Rui; Costa, José L.; Gil, Maria M.; Pombo, AnaSea urchin roe is a gastronomic delicacy appreciated worldwide and Portugal is the third largest consumer nation of seafood. However, sea urchin roe is recognized as a seafood by few members of the national coastal communities. Motivated by an increasing interest of gastronomic and aquaculture sectors in producing this seafood, a survey was conducted among the participants of gastronomic festivals aiming to characterize the motivations and preferences regarding sea urchin roe. The results showed that a high percentage of consumers would be willing to eat sea urchin roe in a restaurant, and approximately half of these were not motivated to buy it in the supermarket. The consumers willing to buy sea urchins in the supermarket, would buy it as the whole urchin or the chilled/frozen roe. In conclusion, sea urchin roe can be characterized as a high valued shellfish to be consumed in restaurants.
- Optimization of extraction conditions for Gracilaria gracilis extracts and their antioxidative stability as mart of microfiber food coating additivesPublication . Reboleira, João; Ganhão, Rui; Mendes, Susana; Adão, Pedro; Andrade, Mariana; Vilarinho, Fernanda; Sanches-Silva, Ana; Sousa, Dora; Mateus, Artur; Bernardino, SusanaIncorporation of antioxidant agents in edible films and packages often relies in the usage of essential oils and other concentrated hydrophobic liquids, with reliable increases in antimicrobial and antioxidant activities of the overall composite, but with less desirable synthetic sources and extraction methods. Hydroethanolic extracts of commercially-available red macroalgae Gracilaria gracilis were evaluated for their antioxidant potential and phenolic content, as part of the selection of algal biomass for the enrichment of thermoplastic film coatings. The extracts were obtained through use of solid-liquid extractions, over which yield, DPPH radical reduction capacity, total phenolic content, and FRAP activity assays were measured. Solid-to-liquid ratio, extraction time, and ethanol percentages were selected as independent variables, and response surface methodology (RSM) was then used to estimate the e ect of each extraction condition on the tested bioactivities. These extracts were electrospun into polypropylene films and the antioxidant activity of these coatings was measured. Similar bioactivities were measured for both 100% ethanolic and aqueous extracts, revealing high viability in the application of both for antioxidant coating purposes, though activity losses as a result of the electrospinning process were above 60% in all cases.
- Poultry shelf-life enhancing potential of nanofibers and nanoparticles containing Porphyra dioica extractsPublication . Reboleira, João; Adão, Pedro; Guerreiro, Sara F.C.; Dias, Juliana R.; Ganhão, Rui; Mendes, Susana; Andrade, Mariana; Vilarinho, Fernanda; Sanches-Silva, Ana; Mateus, Artur; Alves, Nuno; Bernardino, Susana M.Aqueous extracts of commercially available red macroalgae Porphyra dioica were integrated as inner coatings of food-grade polypropylene (PP) films through use of electrospinning and electrospraying technologies. Two coating formulations (A = 5 wt% P. dioica extract and 7.5 wt% polyvinyl alcohol (PVA); B = 1 wt% P. dioica extract, 1 wt% PVA, and 17% gelatine) were evaluated as to their capacity to delay spoilage of minced chicken breasts, through monitoring of microbial growth (total mesophile aerobic colony counts), colour stability, lipid oxidation (thiobarbituric acid reactive substances (TBARS)), and sensory analysis over a 4-day refrigerated storage. Scanning electron microscopy (SEM) imaging revealed an increased nanofiber and nanoparticle density on extract-enriched fibers, without compromise to their morphology or the homogeneity of the coatings. Total microbial counts on coating B samples was significantly (p < 0.001) reduced compared to uncoated plastic wraps. The coated samples also exhibited fewer colour degradation, though the coatings did not di er substantially from uncoated plastic wrap. Sensory analysis test subjects successfully distinguished the raw samples based on their treatment and gave a positive approval rating (66.7%) to the extract-enriched coatings when asked about edibility post storage.