This study examined the potential of using the freshwater shrimp, Caridina nilotica (CNM), and mung beans, Vigna radiata (VRM), to replace Rastrineobola argentea fishmeal (RAF) as the primary protein source in fish feeds in East Africa. Six diets with varying proportions of RAF, CNM, VRM and full fat soybean meal were tested on Nile tilapia (initial body mass ± SD: 3.30 ± 0.27 g). The growth performance was best in groups fed diets containing either R. argentea or C. nilotica or a combination of the two. Growth was poorest in the fish fed a combination of C. nilotica and V. radiata, and intermediate in the groups fed the commercial formulation and a diet containing a combination of R. argentea and V. radiata. The cost of feed per kg of fish produced decreased with increasing inclusion of C. nilotica. The price of feed per kg of fish produced was comparatively high in feeds containing V. radiata due to poor feed conversion ratio. Of all the diets tested, the price of feed per kg of fish produced was highest in the commercial formulation. Caridina nilotica is a good candidate to substitute R. argentea fishmeal in practical diets for Nile tilapia.
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Filleting and freezing in relation to rigor mortis, and a well-controlled cold-chain are important to maintain quality of fish. Atlantic herring (Clupea harengus) was processed and frozen pre or postrigor, and stored at either unstable modeled temperature conditions (at −25 ° C for 2 months, then stressed at −12 ° C for 1 month, followed by −25 ° C for up to 5 months) , or at stable storage conditions (−25 ° C) for 5 months. Analyzes on yield, physicochemical properties, lipid oxidation and hydrolysis of the light and dark muscle were performed. Prerigor freezing and stable storage conditions effectively reduced thawing loss, and inhibited lipid oxidation and hydrolysis of the light muscle. The dark muscle was more susceptible to lipid oxidation than the light; therefore, removal of the dark muscle may increase stability of the more valuable light muscle. Temperature stress must be avoided to maintain quality and extend shelf-life of industrially frozen herring fillets.
Temperature stress and fluctuations are common problems in frozen storage of fish products. This study investigated how storage temperature variations within an industrial frozen storage facility affected the physicochemical properties of Tra catfish (Pangasius hypophthalmus) fillets. Effects of commercial processing additives (mixture of sodium phosphates, sodium chloride, sodium citrate and citric acid), and vacuum packaging on the physicochemical properties of the fillets during 12 months of industrial storage were also studied and compared to controlled storage conditions (−18.6 ± 0.2 ° C). Temperature in the industrial storage was above −18 ° C, which is the recommended temperature for frozen fish products. This accelerated thawing loss, lipid oxidation and hydrolysis. Additives were effective in inhibiting lipid degradation, and retaining cooking yield, while vacuum packaging protected the fish from lipid oxidation and hydrolysis. Most importantly, temperature must be strictly controlled to ensure the quality of Tra catfish products during frozen storage.
Physicochemical changes of Icelandic golden redfish (Sebastes marinus) as affected by seasonal variation (June and November) and raw material freshness (processed 4 and 9 days postcatch) during frozen storage (at −25 ° C for 20 months) were studied to find optimal conditions for production of high ‐ quality frozen products. Thawing loss, cooking yield, and color of the fillets as well as chemical composition, water holding capacity, pH, total volatile basic nitrogen, lipid oxidation, and hydrolysis of the light and dark muscle were analyzed every 4 months of frozen storage. Lipid hydrolysis was the main degradation process in the light muscle, while the dark muscle was more affected by lipid oxidation. Fish caught in November showed greater instability in the analyzed parameters during storage than fish caught in June, which could be linked to differences in individual poly unsaturated fatty acids between the two seasons. The quality attributes of fish processed on day 9 were similar to fish processed 4 days postcatch, except slightly higher thawing loss and yellowness, were observed in fish processed 9 days postcatch. Stability of golden redfish through frozen storage was higher in the fish caught in June than in November.
The distribution and characteristics of water in the muscle of various commercially available Icelandic heavily salted Atlantic cod products were analyzed with proton magnetic resonance methods. The products varied in choice of catching method, in pre- or post-rigor processing, flattening or filleting cut, and pre-salting technique (brine injection with salt with / without polyphosphates, brining and pickling) and choice of brine-injection instruments.
All products had heterogeneous water distributions, but the level of heterogeneity was dependent on the handling during processing. Brine injection led to salt-induced swelling, which effect remained after the kench dry salting step. Double brine injection induced needle traces in the muscle, even after kench salting. Relaxation time analysis indicated that pickle salted products had the highest degree of protein denaturation in the muscle amongst the analyzed pre-salting methods. The multi-parametric analysis indicated how powerful the MR methods are for process and product characterization and optimization.
Fast and non-destructive prediction of the quality characteristics of food products during frozen storage are of great value both for the food industry and the consumers. The current study investigated the potential of using low field Nuclear Magnetic Resonance (NMR) along with multivariate chemometric methods to predict various important physicochemical quality parameters in Atlantic mackerel during frozen storage, as affected by season of catch, freezing method and temperature, as well as frozen storage duration. The obtained results clearly showed that transverse relaxation data obtained by low field NMR can be effectively used to simultaneously predict multiple quality characteristics of the mackerel fillets through storage, including water and lipid content, water holding capacity, lipid oxidation (peroxide value (PV), and thiobartituric reactive substances (TBARS)) and lipid hydrolysis (free fatty acids (FFA)) content within the muscle. The NMR data could furthermore be used to predict variations in the muscle due to season of catch, the frozen storage duration of the mackerel samples when all samples were used, and whether the fish had been headed and gutted or stored whole, which freezing equipment had been used, and the frozen storage temperature for mackerel samples caught at the end of July. Simplified monitoring and optimization of these quality parameters in frozen mackerel with a fast and non-destructive analytical technique like low field NMR is thus of great value for the fishing industry
Marine Synechococcus cyanobacteria are major contributors to global oceanic primary production and exhibit a unique diversity of photosynthetic pigments, allowing them to exploit a wide range of light niches. However, the relationship between pigment content and niche partitioning has remained largely undetermined due to the lack of a single-genetic marker resolving all pigment types (PTs). Here, we developed and employed a robust method based on three distinct marker genes (cpcBA, mpeBA, and mpeW) to estimate the relative abundance of all known Synechococcus PTs from metagenomes. Analysis of the Tara Oceans dataset allowed us to reveal the global distribution of Synechococcus PTs and to define their environmental niches. Green-light specialists (PT 3a) dominated in warm, green equatorial waters, whereas blue-light specialists (PT 3c) were particularly abundant in oligotrophic areas. Type IV chromatic acclimaters (CA4-A / B), which are able to dynamically modify their light absorption properties to maximally absorb green or blue light, were unexpectedly the most abundant PT in our dataset and predominated at depth and high latitudes. We also identified populations in which CA4 might be nonfunctional due to the lack of specific CA4 genes, notably in warm high-nutrient low-chlorophyll areas. Major ecotypes within clades I – IV and CRD1 were preferentially associated with a particular PT, while others exhibited a wide range of PTs. Altogether, this study provides important insights into the ecology of Synechococcus and highlights the complex interactions between vertical phylogeny, pigmentation, and environmental parameters that shape Synechococcus community structure and evolution.
Atlantic salmon (Salmo salar L.) populations from different river origins mix in the North Atlantic during the marine life stage. To facilitate marine stock identification, we developed a genetic baseline covering the European component of the species' range excluding the Baltic Sea, from the Russian River Megra in the north-east, the Icelandic Ellidaar in the west, and the Spanish Ulla in the south , spanning 3737 km North to South and 2717 km East to West. The baseline encompasses data for 14 microsatellites for 26,822 individual fish from 13 countries, 282 rivers, and 467 sampling sites. A hierarchy of regional genetic assignment units was defined using a combination of distance-based and Bayesian clustering. At the top level, three assignment units were identified comprising northern, southern, and Icelandic regions. A second assignment level was also defined, comprising eighteen and twenty-nine regional units for accurate individual assignment and mixed stock estimates respectively. The baseline provides the most comprehensive geographical coverage for an Atlantic salmon genetic data-set, and a unique resource for the conservation and management of the species in Europe. It is freely available to researchers to facilitate identification of the natal origin of European salmon.
Food safety is embedded in food-related problems, and in proposed solutions. Despite continuous investment, the WHO estimates 23 million cases of foodborne illness and 5000 deaths in Europe every year and Europeans are not confident in the food system. Now, the circular economy aims to improve global food security through sustainable production, thus new ingredients, methods and food safety challenges. Food is unequivocally linked to non-communicable diseases, and changes are needed for nutritional food safety. Emerging and re-emerging foodborne pathogens are changing the epidemiology of foodborne diseases. Additionally, some chemicals are of concern, and food is a major source of human exposure. Finally, risk communication is required for management of consumer-based foodborne hazards, yet this foodborne illness is common. We ignore food safety challenges at our peril as potential consequences of a lapse are huge; keeping the food supply safe is a never-ending task.
Background
The continuous high expectations on the world's fisheries to provide products for human consumption is leading to increased overexploitation of fishing stocks. This unsustainable exploitation desperately calls for other suitable resources that can relieve the pressure on the fisheries. The utilization of Calanus finmarchicus has been proposed as a suitable alternative. There is, however, still a question of both ecological and economic sustainability of such exploitation.
Scope and approach
This review describes currently utilized marine resources, and compares the suitability of C. finmarchicus as a useful alternative for those resources. Additionally, the review describes the life history and chemical composition of C. finmarchicus. Current utilization of C. finmarchicus is also described, along with industrial methods used to derive various products from Calanus, as well as a discussion of other potential products from the resource.
Key findings and conclusions
C. finmarchicus can potentially be considered an alternative marine resource as it has a unique lipid composition, is rich in antioxidants, and contains various enzymes. However, the question of sustainable catching remains unanswered and must be addressed before C. finmarchicus can be considered for utilization.