Abstract Jumbo squid (Dosidicus gigas) muscle hardness has been related to hydroxylysyl-pyridinoline (HP) formation (collagen fibre stabilization) via condensation of oxidized ε-amino groups of lysine and/or hydroxylysine by lysyl oxidase (LOX). Previously published literature has suggested the presence of LOX isoforms in squid muscle. Thus, the objective of the present research was to test the hypothesis that squid LOX isoforms exist in fresh mantle muscle. A semi-pure LOX extract (SPLE) was used to perform an immunoblotting assay using two commercial human-LOX antibodies. Furthermore, SPLE (specific activity of 20 mU/mg of protein) was tested in vitro for possible HP formation using several collagenous materials. Immunoblotting assay confirmed the presence of squid LOX at 32 kDa and its isoforms at 34 kDa and 24 kDa. Although LOX oxidized ε-amino groups on collagenous materials, no HP formation was detected. However, the latter could promote interesting collagen functional modifications.

Abstract Loricariid catfish (Pterygoplichthys disjunctivus [Weber, 1991]) has invaded water catchments throughout the world, due to the lack of predators and high fecundity. An approach to control its population could be using its roe as food; however, more knowledge is needed. Thus, the present study aimed to evaluate the shelf-life of fresh loricariid catfish roe stored in ice, as an approach for possible food utilisation. Physicochemical characteristics (moisture content, aw, pH, hardness, and colour), protein electrophoresis (SDS-PAGE), amino and fatty acid contents, oxidative stability (TBARS) and microbiology of roe were analysed at 0, 2, 4, 6, 11, 15 and 21 days. Moisture content (58.5 ± 2.1 vs. 60.4 ± 1.2%), aw (0.89) and pH (5.87 ± 0.14 vs. 5.96 ± 0.03) were shelf-stable (initial vs. final day, respectively). SDS-PAGE showed minor hydrolysis of its protein. Ice storage increased roe free amino acid concentration, confirming proteolysis of its proteins/peptides with not impact on the fatty acid content and TBARS (2.4–3.3 mg malonadehyde/kg sample). Thus, ice storage of fresh loricariid catfish (P. disjunctivus [Weber, 1991]) roe, under the study conditions, proved to be an effective preservation method for its food utilisation, maintaining its physicochemical and microbiological characteristics for up to 20 days.

Abstract Enormous amounts of by-products and waste are generated during the processing of seafood, sometimes representing about 65% of the raw material employed. Seafood by-products (SB) include solid waste such as skin, head, viscera, trimmings, and bones; however, liquid wastes (effluents) derived from operations such as washing, thawing, cooking and the production of fishmeal are also produced. SB contain considerable amounts of protein and others biomolecules, which has been regularly processed as food ingredients for animal nutrition. But also, sometimes SB are used as fertilizers or discarded to environment without a previous treatment. Nowadays, there is an increasing interest in adding value to the protein material within SB by improving their properties through hydrolysis and thus releasing of peptides with bioactive properties. Thus, this review aims to present an overview of the potential of SB, focused on effluents, as a source of protein hydrolysates, summarizing their methods of production, bioactive property evaluation and structural characteristics.

Abstract The present research work determined the effect of the stable and oscillating seawater temperature at three different levels (21, 24 and 28°C), on the physiological condition of the lion’s paw scallop Nodipecten subnodosus. For this, we evaluated the following physiological indicators: adenosine triphosphate content (ATP), glycogen and total carbohydrates, as well as muscle yield index (MYI) and adenylated energy charge, which were determined in the abductor muscle of organisms, extracted directly from the lagoon and after the treatments application. It was found that in the experiment, concentrations of ATP, glycogen content, total carbohydrates, and MYI decreased significantly (P<0.05) after the application of treatments. No effect of temperature level and application form (oscillating and constant) on MYI and CEA was found, however, glycogen content showed a significant affect only from the temperature level, being organisms exposed to 28°C statistically different from those of 24 and 21°C. In conclusion, only the acclimatization temperature level affected the physiological condition of the lion’s paw scallop, being the organisms acclimatized to 28°C the most affected.

Resumen El presente trabajo de investigación determinó el efecto de la temperatura estable y oscilante del agua de mar a tres diferentes niveles (21, 24 y 28°C), sobre la condición fisiológica de la almeja mano de león Nodipecten subnodosus. Para ello, se evaluaron los siguientes indicadores fisiológicos: contenido de adenosina trifosfato (ATP), glucógeno y carbohidratos totales, así como índice de rendimiento muscular (IRM) y carga energética adenilada (CEA), los cuales se determinaron en el músculo abductor de organismos extraídos directamente de la laguna y después de la aplicación de los tratamientos. Se encontró que, en el experimento, las concentraciones de ATP, contenido de glucógeno, carbohidratos totales, e IRM disminuyeron significantemente (P<0.05) después de la aplicación de los tratamientos. No se encontró un efecto del nivel de temperatura y la forma de aplicación (oscilante y constante) en el IRM y CEA, sin embargo, en el contenido de glucógeno se obtuvo un afecto significativo solo del nivel de temperatura, siendo los organismos sometidos a 28°C diferentes (P<0.05) a los de 24 y 21°C. Por lo tanto, se concluyó, que solo el nivel de temperatura de aclimatación afectó la condición fisiológica de la almeja mano de león, siendo los organismos aclimatados a 28°C los más afectados.

El agua de cola es un efluente complejo compuesto por una gran variedad de sólidos, los cuales deben ser removidos en su mayor parte para generar un efluente que pueda ser vertido directamente al mar. En el presente estudio el agua de cola se centrifugó y posteriormente se trató con quitosano a distintos valores de pH y concentraciones con la finalidad de remover sólidos presentes. Mediante la centrifugación se logró remover el 33,88% de los sólidos totales; 28,52% de proteína; 97,50% de grasa; 40% de ceniza y 20% de NNP, y disminuyeron la DBO5 y la DQO en un 42,2 y 63,3% respectivamente. El porcentaje de transmitancia aumentó de 14,6 a 18,4 siendo éste un cambio pequeño en relación al contenido de sólidos removido. La adición de quitosano al agua de cola centrifugada redujo en 25% el contenido de sólidos totales, 55% el de proteína, 40% el de grasa, 24% el de cenizas y 60% el de NNP. De igual forma, disminuyó la DBO5 y la DQO en un 48,4 y 31,2% respectivamente. Como resultado de la adición el porcentaje de transmitancia aumentó de 18,4 a 86,0; indicando que tal aumento se debió principalmente a la remoción de pigmentos y no de materia orgánica. Se logró una disminución importante en DBO5 y DQO; sin embargo, se requieren otras herramientas para reducir estos valores a concentraciones establecidas en la reglamentación sanitaria.

The stickwater is a complex effluent consisting of a variety of solids, most of which should be removed to produce a new effluent that can be directly poured into the sea. In this study, stickwater was centrifuged to remove solids and the resulting liquid was then treated with chitosan at different concentrations and pH to eliminate the solids left in it. Centrifugation extracted 33.88% of total solids, 28.52% protein, 97.50% fat, 40% ash and 20% NPN. It also decreased in 42.2 and 63.3% the BOD5 and COD, respectively. Transmittance percent increased from 14.6 to 18.4, a small change in relation to the content of solids removed. The addition of chitosan to centrifuged stickwater decreased 25% of the total solids content, 55% of protein, 40% fat, 24% ash and 60% NPN. Likewise, the addition of chitosan decreased the BOD5 and COD in 48.4 and 31.2%, respectively. As a consequence, transmittance increased from 18.4 to 86.0%, indicating that such increase was mainly due to the elimination of pigments rather than organic matter. A significant decrease was achieved in BOD5 and COD; nevertheless, other tools are required to reduce these figures to the levels established by the environmental health regulations.

O residuo liquido (stickwater) é un efluente complexo composto por uma grande variedade de sólidos, os quais deven ser removidos principalmente para gerar un efluente que possa ser vertido diretamente ao mar. No presente estudo o residuo líquido foi centrifugado e posteriormente tratado com quitosana a distintos valores de pH e concentrações com a finalidade de remover sólidos presentes. Mediante a centrifugación se conseguiu remover 33,88% dos sólidos totais; 28,52% de proteína; 97,50% de gordura; 40% de cinza e 20% de NNP, e diminuiram a DBO5 e a DQO em 42,2 e 63,3% respectivamente. A porcentagem de transmitância aumentou de 14,6 a 18,4 sendo esta uma mudança pequena em relação ao conteúdo de sólidos removido. A adição de quitosana no residuo líquido centrifugado reduziu em 25% o conteúdo de sólidos totais, 55% o de proteína, 40% o de gordura, 24% o de cinzas e 60% o de NNP. De igual forma, diminuiu a DBO e a DQO em 48,4 y 31,2% respectivamente. Como resultado da adição, a porcentagem de transmitância aumentou de 18,4 a 86,0; indicando que tal aumento foi devido principalmente à remoção de pigmentos e não de matéria orgânica. Alcançou-se uma diminuição importante em DBO5 e DQO; no entanto, são requeridas outras ferramentas para reduzir estes valores a concentrações estabelecidas na regulamentação sanitária.