Fish Loss/Waste and Low-Value Fish Challenges: State of Art, Advances, and Perspectives

Marine Animal Co-Products-How Improving Their Use as Rich Sources of Health-Promoting Lipids Can Foster Sustainability

Marine lipids are recognized for their-health promoting features, mainly for being the primary sources of omega-3 fatty acids, and are therefore critical for human nutrition in an age when the global supply for these nutrients is experiencing an unprecedent pressure due to an ever-increasing demand. The seafood industry originates a considerable yield of co-products worldwide that, while already explored for other purposes, remain mostly undervalued as sustainable sources of healthy lipids, often being explored for low-value oil production. These co-products are especially appealing as lipid sources since, besides the well-known nutritional upside of marine animal fat, which is particularly rich in omega-3 polyunsaturated fatty acids, they also have interesting bioactive properties, which may garner them further interest, not only as food, but also for other high-end applications. Besides the added value that these co-products may represent as valuable lipid sources, there is also the obvious ecological upside of reducing seafood industry waste. In this sense, repurposing these bioresources will contribute to a more sustainable use of marine animal food, reducing the strain on already heavily depleted seafood stocks. Therefore, untapping the potential of marine animal co-products as valuable lipid sources aligns with both health and environmental goals by guaranteeing additional sources of healthy lipids and promoting more eco-conscious practices.

Green Chemistry to Valorize Seafood Side Streams: An Ecofriendly Roadmap toward Sustainability

A major challenge facing sustainable seafood production is the voluminous amounts of nutrient-rich seafood side streams consisting of by-catch, processing discards, and process effluents. There is a lack of a comprehensive model for optimal valorization of the side streams. Upcoming green chemistry-based processing has the potential to recover diverse valuable compounds from seafood side streams in an ecofriendly manner. Microbial and enzymatic bioconversions form major green processes capable of releasing biomolecules from seafood matrices under mild conditions. Novel green solvents, because of their low toxicity and recyclable nature, can extract bioactive compounds. Nonthermal technologies such as ultrasound, supercritical fluid, and membrane filtration can complement green extractions. The extracted proteins, peptides, polyunsaturated fatty acids, chitin, chitosan, and others function as nutraceuticals, food supplements, additives, etc. Green processing can address environmental, economic, and technological challenges of valorization of seafood side streams, thereby supporting sustainable seafood production. Green processing can also encourage bioenergy production. Multiple green processes, integrated in a marine biorefinery, can optimize valorization on a zero-waste trade-off, for a circular blue economy. A green chemistry-based valorization framework has the potential to meet the Sustainable Development Goals (SDGs) of the United Nations.

A bibliometric approach to understanding the recent development of self-sufficient fish feed production utilizing agri-food wastes and by-products towards sustainable aquaculture

The global agri-food industry generates a large volume of waste annually, which causes both environmental and economic problems. Recently, there has been a growing interest in the use of agri-food wastes and by-products to produce self-sufficient fish feed. This study aimed to analyze the intellectual structure of the recent research on the utilization of agri-food wastes and by-products as self-sufficient fish feed materials based on 922 Scopus-indexed core collection documents from 252 journals written by 4420 authors from 73 countries with an annual growth rate of 18.65% over the last four years (2019-2022). This bibliometric study implemented knowledge domain visualization (KDV) using VOSViewer and Biblioshiny in the Bibliometrix R-package to investigate the basic scientometric profile of the selected fields. The results showed that Dawood M.A.O., with PageRanks of 0.0732, 19 total publications, 695 global citations from 2019 to 2022, and closeness values of 0.25, was the most productive author within the field. Subsequently, China was determined to be the most productive country (93 valid documents) and have the strongest collaboration network. Major research hotspots in the field included aquaculture and sustainable aquaculture, fish feed with agri-food waste, rainbow trout species, the development of a circular economy, probiotic applications, and cell signaling cytokines and peptides. This bibliometric study provides comprehensive information on the intellectual domain and research landscape on self-sufficient fish feed and also shows how interest in this research topic and similar ones is growing.

Comparative study on nutritional quality and serum biochemical indices of common carp (Cyprinus carpio) aged 11 to 13 months aged cultured in traditional ponds and land-based container aquaculture systems

In the study, the physical characteristics, nutritional composition, mineral elements, volatile substances, and serum biochemistry of common carp (Cyprinus carpio) after rearing for two months were compared and analyzed to reveal the differences in muscle nutritional quality and serum biochemical indices between fish raised in traditional ponds (TP) and land-based container recirculating aquaculture systems (C-RAS). One hundred fish were selected from each aquaculture mode for the following experiments. Results show that: in terms of physical properties, C-RAS frozen seepage rate was significantly lower than that in TP (P < 0.05), the chewiness, gumminess, springiness, resilience, adhesiveness, cohesiveness, and shearing of C-RAS group were significantly higher than in TP (P < 0.01). Regarding muscle nutrients, the moisture, the crude lipid contents of C-RAS group were significantly lower than that of the TP group (P < 0.05), and the crude protein content of C-RAS group was extremely significantly higher than that in TP (P < 0.01). The saturated fatty acids (ΣSFA) and polyunsaturated fatty acids (ΣPUFA) in the muscle of C-RAS were significantly higher than that in TP (P < 0.01), and monounsaturated fatty acids (ΣMUFA) of C-RAS were significantly lower than that in TP (P < 0.01). Methionine content in C-RAS was significantly higher than that in TP (P < 0.05). In terms of mineral elements, the contents of K and Se in C-RAS were significantly higher than those in TP, and the content of Zn in C-RAS was significantly lower than that in TP (P < 0.05). In terms of volatile substances, nonanal, octanal, and benzaldehyde in C-RAS were significantly lower than those in TP(P < 0.01), 2,3-diethyl-5-methylpyrazine, ethyl 3-methylpentanoate, butyl formate were significantly higher than those in TP (P < 0.01). In terms of serum biochemistry, the glucose index in C-RAS was extremely significantly lower than that in TP group, total protein, albumin, alkaline phosphatase, and triglyceride were extremely significantly higher than those in TP (P < 0.01). Experiments show that the aquaculture mode has a large impact on the physical properties of the common carp, nutrients, mineral elements, volatile matter, and serum biochemical. In conclusion, the common carp cultured in C-RAS systems had better muscle nutritional quality, which provides a reference for future regulation of fish nutritional quality by C-RAS.

Functional proteins through green refining of seafood side streams

Scarcity of nutritive protein is a major global problem, the severity of which is bound to increase with the rising population. The situation demands finding additional sources of proteins that can be both safe as well as acceptable to the consumer. Food waste, particularly from seafood is a plausible feedstock of proteins in this respect. Fishing operations result in appreciable amounts of bycatch having poor food value. In addition, commercial processing results in 50 to 60% of seafood as discards, which consist of shell, head, fileting frames, bones, viscera, fin, skin, roe, and others. Furthermore, voluminous amounts of protein-rich effluents are released during commercial seafood processing. While meat from the bycatch can be raw material for proteinous edible products, proteins from the process discards and effluents can be recovered through biorefining employing upcoming, environmental-friendly, low-cost green processes. Microbial or enzyme treatments release proteins bound to the seafood matrices. Physico-chemical processes such as ultrasound, pulse electric field, high hydrostatic pressure, green solvent extractions and others are available to recover proteins from the by-products. Cultivation of photosynthetic microalgae in nutrient media consisting of seafood side streams generates algal cell mass, a rich source of functional proteins. A zero-waste marine bio-refinery approach can help almost total recovery of proteins and other ingredients from the seafood side streams. The recovered proteins can have high nutritive value and valuable applications as nutraceuticals and food additives.

Conversion of Fishery Waste to Proteases by Streptomyces speibonae and Their Application in Antioxidant Preparation

Proteinaceous wastes from the fishery process are an abundant renewable resource for the recovery of a variety of high-value products. This work attempted to utilize several proteinaceous wastes to produce proteases using the Streptomyces speibonae TKU048 strain. Among different possible carbon and nitrogen sources, the protease productive activity of S. speibonae TKU048 was optimal on 1% tuna head powder. Further, the casein/gelatin/tuna head powder zymography of the crude enzyme revealed the presence of three/nine/six proteases, respectively. The crude-enzyme cocktail of S. speibonae TKU048 exhibited the best proteolytic activity at 70 °C and pH = 5.8. Sodium dodecyl sulfate strongly enhanced the proteolytic activity of the cocktail, whereas FeCl3, CuSO4, and ethylenediaminetetraacetic acid could completely inhibit the enzyme activity. Additionally, the crude-enzyme cocktail of S. speibonae TKU048 could efficiently enhance the 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities of all tested proteinaceous materials including the head, viscera, and meat of tuna fish; the head, viscera, and meat of tilapia fish; the head, meat, and shell of shrimp; squid pen; crab shell; and soybean. Taken together, S. speibonae TKU048 revealed potential in the reclamation of proteinaceous wastes for protease production and antioxidant preparation.