The characteristics of flounder (Paralichthys patagonicus) were evaluated during a 12‐day period of storage in ice by monitoring the biochemical, microbiological and sensory parameters. The adenosine‐5′‐triphosphate and adenosine‐5′‐diphosphate were not detected, and the initial content of adenosine‐5′‐monophosphate (AMP) rapidly decreased to zero. Inosine‐5′‐monophosphate (IMP) but not adenosine (Ado) was present in muscle extracts. The AMP deaminase activity was found in the muscle. Conversely, the Ado deaminase activity was not detected. A 55% decrease in IMP concentration occurred during the first 2 days of storage. The inosine content was barely detectable (<0.1 μmol/g), probably because of the high nucleoside phosphorylase activity in the muscle. Hypoxanthine significantly (P < 0.01) increased up to the seventh day and then remained approximately constant. The muscle pH fluctuated between 6.6 and 7.0. The iced flounder was microbiologically acceptable for up to 7 days with aerobic plate counts reaching <107 cfu/g. The sensory score, determined by the Quality Index Method, linearly increased (r2 = 0.96) with the keeping time. All the parameters, including the K‐value, indicated that the shelf life of iced flounder was 7 days.

Fish discards are of major concern in new EU policies. Alternatives for the management of the new biomass that has to be landed is compulsory. The production of bioactive compounds from fish protein hydrolysates (FPH) has been explored in recent years. However, the viability of Scyliorhinus canicula discards, which might account for up to 90–100% of captures in mixed trawler, gillnet, and longline industrial fisheries, to produce FPH from the muscle with bioactivities has still not been studied in terms of the optimization of the experimental conditions to enhance its production. The effect of pH and temperature on the hydrolysis of the S. canicula muscle was mediated by three commercial proteases using response surface methodology. Temperatures of 64.6 °C and 60.8 °C and pHs of 9.40 and 8.90 were established as the best hydrolysis conditions for Alcalase and Esperase, respectively. Optimization of the best conditions for the maximization of antihypertensive and antioxidant activities was performed. Higher Angiotensin-converting enzyme (ACE) activity was found with Esperase. The pH optimum and temperature optimum for antioxidants were 55 °C/pH8.0 for ABTS/DPPH-Esperase, 63.1 °C/pH9.0 for DPPH-Alcalase, and 55 °C/pH9.0 for ABTS-Alcalase. No hydrolysis was detected when using Protamex.

The objective of this study was to develop a quality index method for Engraulis anchoita stored in ice and to determine its shelf-life based on this quality index method and chemical indices such as total volatile bases and thiobarbituric acid-reactive substances. Besides, the chemical composition with emphasis on the polyunsaturated fatty acids content was determined. The results indicate that E. anchoita is a valuable protein source and lipid with important content of n-3 polyunsaturated fatty acids. The developed quality index method scheme was composed of 28 demerit points, divided into 4 parameters and 10 attributes. All attributes showed correlation with time of storage (R > 0.90). The quality index (QI) presented a linear relationship with storage (QI = 2.55x days in ice + 1.76; R²= 0.98). In the shelf-life assessment-based quality index method, the rejection sensory point was observed after 7 days of storage due to the presence of unpleasant odours and deteriorated appearance. The total volatile basic nitrogen value remained below the upper limit of acceptability during the 10 days of ice storage. The evolution of thiobarbituric acid-reactive substances indicates lipids oxidation during the storage of anchovies. According to the results, the quality index method scheme developed for the E. anchoita stored in ice could be considered adequate to evaluate their freshness and to estimate its shelf-life.

This study examined the southern or Patagonian (41°–55° S) stock of Argentine hake Merluccius hubbsi, the more abundant of the two stocks on the Argentinean continental shelf. Pre‐recruits (age 0+ year individuals) of this stock settle and grow in the San Jorge Gulf (45°–47° S, 65° 30′ W), a complex habitat with large spatial variability in environmental features. Relative condition factor, hepatosomatic index, lipid content and fatty‐acid composition of muscle and liver, and diet information were combined with physical and biological data to evaluate: how nutritional status of age 0+ year hake varies spatially within the nursery ground; whether changes in condition are related to environmental factors and feeding; whether the indices are interchangeable metrics of condition. Both morphometric and biochemical indices showed dissimilar spatial trends; enhanced liver‐based condition coincided with low salinity nutrient rich waters, higher chlorophyll‐a values and abundances of Euphausia spp., the preferred prey at most stations, suggesting a bottom‐up effect on age 0+ year hake condition. Diminished condition at stations where Thermisto gaudichaudii was the main prey could derive from lower prey quality in terms of energy density and essential fatty acids content. Coastal waters of the gulf would be essential habitats for M. hubbsi pre‐recruits. Future monitoring of condition with liver‐based indices is encouraged in the gulf, where interannual increasing trends of satellite‐derived chlorophyll‐a values have been observed, which could have implications for recruitment of the species.

No abstract

Fish survival at early life stages depends on the temporal and spatial overlap with prey resources, following the match-mismatch hypothesis (Cushing, 1990). In temperate ecosystems, variability in physical and biological features such as the onset of stratification, light availability and the occurrence of phytoplankton blooms affects the seasonal and spatial patterns of zooplankton abundance, which further influences the feeding success of planktivorous fish. Adequate feeding translates into energy reserves stored within individuals, which reflect their well-being or physiological condition to accomplish essential biological processes such as growth and reproduction

Marine by-products contain valuable protein fractions. To ensure a profitable utilization of wastes from the fish industry, the knowledge about their quality and composition is necessary. Fish digestive proteolytic enzymes from cold-adapted ectothermic organisms have found applications in several industries because their temperature requirements and other characteristics differ from those of homologous proteases from warm-blooded animals. Herein, we describe detection, partial purification, and characterization of proteolytic enzymes from the viscera and heads of Engraulis anchoita. Enzymatic activities of the by-products were assayed using azocaseín as a substrate. To characterize the alkali protein fraction, the activity against inhibitors and their molecular weights were studied. The crude protein extract exhibited maximal activity at pH 8.0 and 60EC. Results relative to the substrate-specific Nabenzoyl-DL-arginine-p-nitroanilide and the 25 kDa molecular weight indicated that the recovered protease was trypsin. The activity showed an increment in presence of SDS and a slight decrease when it was incubated with EDTA. Increasing the concentration of NaCl up to 5% did not significantly decrease the protein's activity. The results obtained suggest that by-products of anchovy industry could be used in the detergents industry.

Percophis brasiliensis is a demersal species that constitutes an important resource of Argentine coastal fisheries. Nevertheless, information about bioenergetic dynamic of reproduction has not been reported. Therefore, seasonal variations of condition factors, biochemical composition and energy density of different tissues were analyzed in order to determine the strategy of energy allocation during the reproductive cycle of this species. Condition indices (hepatosomatic and K) showed a seasonal pattern opposite to that observed for gonadosomatic index, which was characterized by higher values during the reproductive period (spring-summer), decreasing at the end of spawning. Biochemical composition of different tissues also showed a clearly seasonality associated to reproductive cycle. Analysis of energy density variation of liver indicates that P. brasiliensis accumulate reserves in winter before reproduction, which later decrease during the spawning season. In contrast, the energy density in muscle did not show significant differences among seasons, indicating that individuals could be also using an external source of energy during spawning. Therefore, it is possible that P. brasiliensis respond to an intermediate strategy of energy allocation, combining characteristics of both capital breeders (stores energy previous to the onset of reproductive activity) and income breeders (acquire energy by active feeding during spawning period).