J. Aníbal

Seasonal Variations in Gross Biochemical Composition, Percent Edibility, and Condition Index of the Clam Ruditapes decussatus Cultivated in the Ria Formosa (South Portugal)

ABSTRACT The grooved carpet shell clam Ruditapes decussatus (L. 1758) is one of the most popular and profitable molluscs exploited in rearing plots in the Mediterranean. However, annual catch has been declining steadily since the early 1990s. To understand the seasonality of its nutritional value, thus providing an improved basis for economic valuation of the resource, gross biochemical composition, percent edibility, and condition index were investigated during a year with monthly periodicity in a commercially exploited population of the clam R. decussatus in the Ria Formosa, a temperate mesotidal coastal lagoon located in the south of Portugal. Our results show that total and nonprotein nitrogen covaried during the year, resulting in a protein content that peaked in the warmest months. Although complementary in summer, carbohydrate and lipid contents showed irregular annual trends. The observed seasonality was comparable with that shown by studies elsewhere at similar latitudes, and is underpinned by the reproductive cycle of the species. Our results show the clams to be at their prime nutritional value at the beginning of summer, when protein content peaks.

Interception of nutrient rich submarine groundwater discharge seepage on European temperate beaches by the acoel flatworm, Symsagittifera roscoffensis.

Submarine groundwater discharge (SGD) occurs in intertidal areas, representing a largely unquantified source of solute fluxes to adjacent coastal zones, with nitrogen being constantly the keynote chemical of concern. In Olhos de Água SGD is present as groundwater springs or merely sub-aerial runoff. The occurrence of the flatworm Symsagittifera roscoffensis is described for the first time in Olhos de Água in connection to seepage flows. To assess the impact of this symbiotic flatworm on the nitrogen associated to groundwater discharge flow at the beach, nitrate uptake experiments were conducted in laboratory microcosms. Our results show that S. roscoffensis actively uptakes nitrate at different rates depending on light availability, with rates ≈ 10 times higher than that of its symbiotic microalgae alone. This supports the hypothesis that S. roscoffensis could be an important in situ nitrate interceptor, potentially playing a biological role on the transformation of groundwater-borne nitrate loads at the land-ocean boundary.

Age and growth in the Alfonsino, Beryx splendens (Berycidae) from the Azores (central eastern Atlantic)

Abstract Age was determined in the Alfonsino, Beryx splendens, by counting the opaque rings on the anti‐sulcal surface of left sagittae obtained from specimens, 15–43.5 cm fork length (FL), caught off the Azores. Females were from 1 to 12 years old and males were 1 to 9 years old. Von Bertalanffy (VB) growth equations were fitted to data obtained from age‐length keys, back calculation, and length‐frequency analyses. Growth was compared between sexes and among methods. Growth was similar in males, whereas in females the equations derived from length‐frequency analysis overestimated length‐at‐age relative to other methods. Sex specific growth could not be confirmed.

Physicochemical and Microbiological Changes in Dried Small-Spotted Catshark (Scyliorhynus canicula): Contributing to the Developing an Alternative Shark-Based Salted-Dried Seafood Product

ABSTRACT Our aim is to contribute to the valorization and optimization of a salted-dried seafood product prepared from small-spotted catshark (Scyliorhynus canicula) akin to “litão seco,” the high-priced, traditional dried blackmouth catshark (Galeus melastomus). This work focused on studying the changes in physicochemical and microbiological parameters of S. canicula salted (for 3 h or 24 h) and dried (convection oven for 24 h or tray drier for 3 h). As expected, salting and drying reduced the water content and water activity, while chloride content in fillets increased. Also, significant but distinct changes in color, namely CIE L* and b*, were observed. Total viable counts were significantly reduced in the salted-dried shark, but the later still presented Staphylococcus aureus, though at marginally acceptable, non-hazardous levels. The abundance of yeasts was reduced by 3 log(cfu/g) in samples oven-dried for 24 h but only by 0.8 log after 3 h in the tray-drier. From our results, salted-dried S. canicula has the required physicochemical characteristics and microbiological quality to be apt for human consumption and is a suitable candidate for becoming a traditional seafood product comparable to “litão seco.”

Effects of Spoilage on Nitrogen and Carbon Stable Isotopes Signatures of the Clam Ruditapes decussatus

Fish and seafood products are highly susceptible to post-mortem spoilage due to autolytic reactions at start, then microbiological activity and eventually oxidative reactions. Chemical and microbiological parameters are usually used to assess quality and make decisions for protecting public health, but they lack precision in defining which spoilage pathway is occurring at each moment. The objective of this work was to assess the effects of spoilage reactions on nitrogen and carbon stable isotopes in the grooved carpet shell clam, Ruditapes decussatus, and compare them to biochemical indicators of seafood deterioration, in order to better understand the relations between the different spoilage pathways during commercial storage conditions. Clams were kept in a refrigerator at 5 °C, to simulate normal commercial storage conditions, and sampled in the beginning of the experiment, and after eight, ten and twelve days. Moisture, condition index, percentage edibility, total volatile basic nitrogen (TVB-N), pH, nitrogen and carbon percentages and stable isotopes were determined for each sampling moment. Stable isotope analyses were performed using a Costech Elemental Analyzer (ECS 4010) coupled to a Thermo Finnigan Delta V Advantage. Stable isotopes analysis, especially for nitrogen, proved to be a good tool for the study of clam deterioration. Nitrogen stable isotopes results showed a relation with other spoilage indicators, such as pH and TVB-N, and allowed identifying spoilage specific pathways, such as amino acids decarboxylation and production of volatile nitrogen compounds.

Muxama and Estupeta: Traditional Food Products Obtained from Tuna Loins in South Portugal and Spain

In the south of Portugal (Algarve) and Spain (Andalucia), tuna has been traditionally consumed in three different ways: fresh, as tuna steaks; canned, e.g., in olive oil; and cured, salted, and/or salted-dried. The latter includes Muxama and Estupeta that are described herein. The word Muxama (in Portugal) or Mojama (in common use in Spain) comes from the Arab musama and means “dry.” The production of Muxama was developed by the Arabs more than a thousand years ago, based on a combination of (dry) salt preservation of tuna loins followed by drying. It is marketed in vacuum packages. On the other hand, Estupeta—a narrow piece of white, lipid- and fiber-rich muscle closely located to the dorsal loins—is cut from the loins and brined. It is marketed packed in glass jars filled with a light-brine solution.