Fish viscera protein hydrolysates: Production, potential applications and functional and bioactive properties

Atlantic salmon (Salmo salar) waste as a unique source of biofunctional protein hydrolysates: Emerging productions, promising applications, and challenges mitigation

The Atlantic salmon is an extremely popular fish for its nutritional value and unique taste among several fish species. Researchers are focusing on the utilization of Atlantic salmon waste for generating protein hydrolysates rich in peptides and amino acids and investigating their health benefits. Several technological approaches, including enzymatic, chemical, and the recently developed subcritical water hydrolysis, are currently used for the production of Atlantic salmon waste protein hydrolysates. Hydrolyzing various wastes, e.g., heads, bones, skin, viscera, and trimmings, possessing antioxidant, blood pressure regulatory, antidiabetic, and anti-inflammatory properties, resulting in applications in human foods and nutraceuticals, animal farming, pharmaceuticals, cell culture, and cosmetics industries. Furthermore, future applications, constraints several challenges associated with industrial hydrolysate production, including sensory, safety, and economic constraints, which could be overcome by suggested techno processing measures. Further studies are recommended for developing large-scale, commercially viable production methods, focusing on eradicating sensory constraints and facilitating large-scale application.

Unexplored Opportunities of Utilizing Food Waste in Food Product Development for Cardiovascular Health

PURPOSE OF REVIEW

Global food production leads to substantial amounts of agricultural and food waste that contribute to climate change and hinder international efforts to end food insecurity and poverty. Food waste is a rich source of vitamins, minerals, fibers, phenolic compounds, lipids, and bioactive peptides. These compounds can be used to create food products that help reduce heart disease risk and promote sustainability. This review examines the potential cardiovascular benefits of nutrients found in different food waste categories (such as fruits and vegetables, cereal, dairy, meat and poultry, and seafood), focusing on animal and clinical evidence, and giving examples of functional food products in each category.

RECENT FINDINGS

Current evidence suggests that consuming fruit and vegetable pomace, cereal bran, and whey protein may lower the risk of cardiovascular disease, particularly in individuals who are at risk. This is due to improved lipid profile, reduced blood pressure and increased flow-mediated dilation, enhanced glucose and insulin regulation, decreased inflammation, as well as reduced platelet aggregation and improved endothelial function. However, the intervention studies are limited, including a low number of participants and of short duration. Food waste has great potential to be utilized as cardioprotective products. Longer-term intervention studies are necessary to substantiate the health claims of food by-products. Technological advances are needed to improve the stability and bioavailability of bioactive compounds. Implementing safety assessments and regulatory frameworks for functional food derived from food waste is crucial. This is essential for maximizing the potential of food waste, reducing carbon footprint, and improving human health.

Optimization of the autolysis of rainbow trout viscera for amino acid release using response surface methodology

Background

Due to the huge amounts of their production in Europe, their environmental impact, and the difficulty in processing them, there is a clear necessity for the valorization of rainbow trout viscera. Considering that the production of fishmeal with viscera can be problematic, and in order to make viscera more profitable, the production of fish protein hydrolysates has been considered. Although silage and enzymatic hydrolysis are the most common methods for obtaining hydrolysates, autolysis has emerged as an alternative method that uses endogenous enzymes of the viscera.

Methods

Considering the stability and characteristics of the enzymes, a factorial design was carried out using three variables: pH, temperature, and water content. The design resulted in 15 experiments, and the results were analyzed using response surface methodology. The optimum parameters were validated by comparing the predicted outcomes with experimental results. Additionally, a kinetics study was conducted to shorten the autolysis time. Results from autolysis were compared with those from silage and enzymatic hydrolysis in a previous study.

Results

The optimal conditions for achieving the highest degree of hydrolysis and yield of free amino acids (FAAs) per 100 g of viscera and per total protein were determined to be a pH of 8, a temperature of 40 °C, and a water content of 6.85%. The pH and content of the added water were found to be significant variables during autolysis ( p < 0.05). The kinetic study showed that 7 h was still required to be effective.

Conclusions

Autolysis achieved a lower degree of hydrolysis than silage; however, as it solubilized more protein, the global yield of free amino acids per 100 g of viscera was slightly higher. It was concluded that endogenous alkaline proteases could be used in an autolytic process to obtain a free amino acid-rich hydrolysate from trout viscera.

Diverse uses of valuable seafood processing industry waste for sustainability: a review

Seafoods are rich in untapped bioactive compounds that have the potential to provide novel ingredients for the development of commercial functional foods and pharmaceuticals. Unfortunately, a large portion of waste or discards is generated in commercial processing setups (50-80%), which is wasted or underutilized. These by-products are a rich source of novel and valuable biomolecules, including bioactive peptides, collagen and gelatin, oligosaccharides, fatty acids, enzymes, calcium, water-soluble minerals, vitamins, carotenoids, chitin, chitosan and biopolymers. These fish components may be used in the food, cosmetic, pharmaceutical, environmental, biomedical and other industries. Furthermore, they provide a viable source for the production of biofuels. As a result, the current review emphasizes the importance of effective by-product and discard reduction techniques that can provide practical and profitable solutions. Recognizing this, many initiatives have been initiated to effectively use them and generate income for the long-term sustainability of the environment and economic framework of the processing industry. This comprehensive review summarizes the current state of the art in the sustainable valorisation of seafood by-products for human consumption. The review can generate a better understanding of the techniques for seafood waste valorisation to accelerate the sector while providing significant benefits.

Effects of Various Decellularization Methods for the Development of Decellularized Extracellular Matrix from Tilapia (Oreochromis niloticus) Viscera

Tilapia, a widely farmed aquaculture fish, produces substantial waste, including viscera that contain extracellular matrix (ECM) utilized as a biomaterial for tissue regeneration applications. Extracting ECM from viscera requires a specific decellularization method, as no standardized protocol exists. This study performed three decellularization methods: sonication, orbital shaking at room temperature, and agitation at 4°C, using SDS and TX100 at concentrations of 0.1% and 0.3%. The effectiveness of each method was assessed through H&E staining, dsDNA quantification, and SEM imaging to verify cellular content removal and ECM structure preservation. Additional analyses, including ATR-FTIR, SDS-PAGE, protein quantification, HPLC, and detergent residue tests, were performed to examine functional groups, collagen composition, protein content, amino acid profiles, and detergent residues in the decellularized samples. The results of H&E staining showed a significant reduction in cellular components in all samples, which was confirmed through DNA quantification. Sonication with 0.3% SDS achieved the highest DNA removal rate (96.5 ± 1.1%), while SEM images revealed that agitation at 4°C with 0.3% TX100 better preserved ECM structure. Collagen was present in all samples, as confirmed by ATR-FTIR analysis, which revealed pronounced spectral peaks in the amide I, II, III, A, and B regions. Samples treated with agitation at 4°C using 0.1% SDS exhibited the highest protein content (875 ± 15 µg/mg), whereas those treated with TX100 had lower detergent residue. Overall, the decellularization methods effectively reduced DNA content while preserving ECM structure and components, highlighting the potential of tilapia viscera as bioscaffolds and offering insights into utilizing fish waste for high-value products.

Exploring the Multifaceted Potential of Endangered Sturgeon: Caviar, Meat and By-Product Benefits

Sturgeons are facing critical endangerment due to overfishing, habitat destruction, pollution and climate change. Their roe, highly prized as caviar, has driven the overexploitation, severely depleting wild populations. In recent years sturgeon aquaculture has experienced significant growth, primarily aimed at providing high-quality caviar and secondarily meat. This sector generates significant quantities of by-products, which are mainly treated as waste, being mostly discarded, impacting the environment, even though they are a source of bioactive molecules and potential applications in various sectors. This article presents a review of the proximate composition and nutritional value of sturgeon caviar and meat, also exploring the potential of the by-products, with an emphasis on the processing of these components, the chemical composition and the functional and bioactive properties. Although sturgeon caviar, meat, and by-products are highly valuable both nutritionally and economically, adopting sustainable practices and innovative approaches is crucial to ensuring the industry's future growth and maintaining ecological balance. Despite some limitations, like the deficient standardization of the methods for extracting and processing, sturgeon by-products have a tremendous potential to increase the overall value of sturgeon aquaculture and to promote a zero-waste approach, contributing to achieving the Sustainable Development Goals adopted by all United Nations Member States in 2015.

The Revalorization of Fishery By-Products: Types, Bioactive Compounds, and Food Applications

Recently, fish consumption has been increasing; subsequently, the number of by-products has also increased. However, generated residues are frequently discarded, and an appropriate management is necessary to properly use all fish by-products. Fishery by-products are well known for their content of bioactive compounds, such as unsaturated fatty acids, amino acids, minerals, peptides, enzymes, gelatin, collagen, and chitin. Several studies have reported that fishery by-products could provide significant properties, including antioxidant, antihypertensive, antimicrobial, anti-inflammatory, and antiobesity. Consequently, fish discards are of considerable interest to different industrial sectors, including food, nutraceuticals, medical, and pharmacology. In the food industry, the interest in using fishery by-products is focused on hydrolysates as food additives, collagen and gelatin as protein sources, chitin and chitosan to form edible films to protect food during storage, and oils as a source of Omega-3 and useful as antioxidants. Although different studies reported good results with the use of these by-products, identifying new applications in the food sector, as well as industrial applications, remains necessary.

Encapsulation of zingerone by self-assembling peptides derived from fish viscera: Characterization, interaction and effects on colon epithelial cells

The purpose of the present work was to encapsulate zingerone (a bioactive compound from ginger) by self-assembling peptides derived from fish viscera. The encapsulation conditions were investigated and the structure of fish peptides-zingerone complex was characterized. The interaction between zingerone and fish peptides was investigated using fluorescence spectroscopy. Further research was performed on the in vitro release of zingerone and fish peptide-zingerone as well as their antiproliferative effects on colon epithelial Caco-2 cells. The results demonstrated that zingerone can be successfully encapsulated by self-assembling peptides derived from fish viscera with high encapsulation efficiency and loading capacity. Furthermore, transmission electron microscope and confocal laser scanning microscope observations revealed the successful encapsulation of zingerone by fish viscera peptides. In addition, in vitro release and antiproliferative activity against Caco-2 cells can be significantly increased by encapsulating zingerone via peptide self-assembly. The current study advances knowledge of encapsulation of bioactive compounds through peptide self-assembly.

Antioxidant and antiproliferative activity of enzymatic hydrolysates from red tilapia (Oreochromis spp.) viscera

The antioxidant and antiproliferative activity of red tilapia (Oreochromis spp.) viscera hydrolysates (RTVH) was evaluated. For that, the hydrolysates was applied to three cancer cell lines (HepG2, Huh7 and SW480) and the control (CCD-18Co). Finally, the line on which the hydrolysate had the greatest effect (SW480) and the control (CCD-18Co) were subjected to the ApoTox-Glo Triplex Assay to determine apoptosis, toxicity, and cell viability. The result showed that hydrolysate had a dose-dependent cytotoxic effect selective on the three cancer cell lines, compared to the control cells. There is a relationship between the antioxidant capacity of RTVHs and their antiproliferative capacity on cancer cells evaluated, which achieved cell viability by action of RTVH of 34.68 and 41.58 and 25.41 %, to HepG2, Huh7 and SW480, respectively. The action of RTVH on cancer cell line SW480 is not due to the induction of apoptosis but to the rupture of the cell membrane.

Review of fish protein hydrolysates: production methods, antioxidant and antimicrobial activity and nanoencapsulation

Marine products have gained popularity due to their valuable components, especially protein, despite generating significant waste. Protein hydrolysates are widely recognized as the most effective method for transforming these low-value raw materials into high-value products. Fish protein hydrolysate (FPH), sourced from various aquatic wastes such as bones, scales, skin, and others, is rich in protein for value-added products. However, the hydrophobic peptides have limitations like an unpleasant taste and high solubility. Microencapsulation techniques provide a scientific approach to address these limitations and safeguard bioactive peptides. This review examines current research on FPH production methods and their antioxidant and antibacterial activities. Enzymatic hydrolysis using commercial enzymes is identified as the optimal method, and the antioxidant and antibacterial properties of FPH are substantiated. Microencapsulation using nanoliposomes effectively extends the inhibitory activity and enhances antioxidant and antibacterial capacities. Nevertheless, more research is needed to mitigate the bitter taste associated with FPH and enhance sensory attributes.

Potential inhibitory effect of highland barley protein hydrolysates on the formation of advanced glycation end-products (AGEs): A mechanism study

Advanced glycation end products (AGEs) can be caused during a glycoxidation reaction. This reaction is associated with complications of diabetes and the consequences of health problems. Therefore, we are exploring the prohibitory effect of highland barley protein hydrolysates (HBPHs) on AGE formation. Herein, first extracted the protein from highland barley with various pH conditions and then hydrolyzed using four different proteolytic enzymes (flavourzyme, trypsin, papain, pepsin) under different degrees of hydrolysis. We assessed three degrees of hydrolysates (lowest, middle, highest) of enzymes used to characterize the antioxidant activity and physicochemical properties. Among all the hydrolysates, flavourzyme-treated hydrolysates F-1, F-2, and F-3 indicated the high ability to scavenge DPPH (IC50 values of 0.97 %, 0.63 %, and 0.90 %), structural and functional properties. Finally, the inhibitory effect of the most active hydrolysates F-1, F-2, and F-3 against the AGEs formation was evaluated in multiple glucose-glycated bovine serum albumin (BSA) systems. Additionally, in a BSA system, F-3 exhibited the strong antiglycation activity, effectively suppressed the non-fluorescent AGE (CML), and the fructosamine level. Moreover, it decreased carbonyl compounds while also preventing the loss of thiol groups. Our results would be beneficial in the application of the food industry as a potential antiglycation agent for several chronic diseases.

Comparison of amino acid release between enzymatic hydrolysis and acid autolysis of rainbow trout viscera

Fish protein hydrolysates were obtained from cultured rainbow trout (Oncorhynchus mykiss) viscera using commercial and endogenous enzymes. Two methods were employed for hydrolysis: acid autolysis (also known as silage) at room temperature for 10 days in acidic conditions, until total solubilisation, and enzymatic hydrolysis using Alcalase 2.4 LFG, Protana Prime, and the endogenous enzymes in the viscera. The effectiveness of both methods in releasing free amino acids (FAA) was assessed. After evaluating the results, the most effective enzymatic hydrolysis was optimized. The findings indicated that enzymatic hydrolysis with Alcalase, Protana Prime and endogenous enzymes combined for 7 h at a dose of 1% of protein, and a 7-day acid autolysis yielded the highest degree of hydrolysis (83.8% and 75.8%), a yield of FAA from viscera of 5.9% and 3.2%, and a yield of FAA from total protein of 71.3% and 52.5%, respectively. In conclusion, the use of commercial enzymes was more efficient in releasing amino acids, but endogenous enzymes showed a strong proteolytic capacity during acid autolysis, suggesting it also as a promising method to produce FAA-rich hydrolysates.

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.

Regenerative Food Innovation: The Role of Agro-Food Chain By-Products and Plant Origin Food to Obtain High-Value-Added Foods

Food losses in the agri-food sector have been estimated as representing between 30 and 80% of overall yield. The agro-food sector has a responsibility to work towards achieving FAO sustainable goals and global initiatives on responding to many issues, including climate pressures from changes we are experiencing globally. Regenerative agriculture has been discussed for many years in terms of improving our land and water. What we now need is a focus on the ability to transform innovation within the food production and process systems to address the needs of society in the fundamental arenas of food, health and wellbeing in a sustainable world. Thus, regenerative food innovation presents an opportunity to evaluate by-products from the agriculture and food industries to utilise these waste streams to minimise the global effects of food waste. The mini-review article aims to illustrate advancements in the valorisation of foods from some of the most recent publications published by peer-reviewed journals during the last 4-5 years. The focus will be applied to plant-based valorised food products and how these can be utilised to improve food nutritional components, texture, sensory and consumer perception to develop the foods for the future.

Antioxidant, Antibacterial Properties of Novel Peptide CP by Enzymatic Hydrolysis of Chromis notata By-Products and Its Efficacy on Atopic Dermatitis

This study investigated the antioxidant, antimicrobial, and anti-atopic dermatitis (AD) effects of a novel peptide (CP) derived from a Chromis notata by-product hydrolysate. Alcalase, Flavourzyme, Neutrase, and Protamex enzymes were used to hydrolyze the C. notata by-product protein, and the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activity was measured. Alcalase hydrolysate exhibited the highest ABTS radical-scavenging activity, leading to the selection of Alcalase for further purification. The CHAO-1-I fraction, with the highest ABTS activity, was isolated and further purified, resulting in the identification of the peptide CP with the amino acid sequence Ala-Gln-Val-Met-Lys-Leu-Pro-His-Arg-Met-Gln-His-Ser-Gln-Ser. CP demonstrated antimicrobial activity against Staphylococcus aureus, inhibiting its growth. In a 2,4-dinitrochlorobenzene (DNCB)-induced AD-like skin model in mice, CP significantly alleviated skin lesions, reduced epidermal and dermal thickness, and inhibited mast cell infiltration. Moreover, CP suppressed the elevated levels of interleukin-6 (IL-6) in the plasma of DNCB-induced mice. These findings highlight the potential of CP as a therapeutic agent for AD and suggest a novel application of this C. notata by-product in the fish processing industry.

Enzymatic Preparation and Processing Properties of DPP-IV Inhibitory Peptides Derived from Wheat Gluten: Effects of Pretreatment Methods and Protease Types

The choice of appropriate proteases and pretreatment methods significantly influences the preparation of bioactive peptides. This study aimed to investigate the effects of different pretreatment methods on the hydrolytic performance of diverse proteases during the production of dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides derived from wheat and their foaming and emulsion properties. Dry heating, aqueous heating, and ultrasound treatment were employed as pretreatments for the protein prior to the enzymatic hydrolysis of wheat gluten. FTIR analysis results indicated that all pretreatment methods altered the secondary structure of the protein; however, the effects of dry heating treatment on the secondary structure content were opposite to those of aqueous heating and ultrasound treatment. Nevertheless, all three methods enhanced the protein solubility and surface hydrophobicity. By using pretreated proteins as substrates, five different types of proteases were employed for DPP-IV inhibitory peptide production. The analysis of the DPP-IV inhibitory activity, degree of hydrolysis, and TCA-soluble peptide content revealed that the specific pretreatments had a promoting or inhibiting effect on DPP-IV inhibitory peptide production depending on the protease used. Furthermore, the pretreatment method and the selected type of protease collectively influenced the foaming and emulsifying properties of the prepared peptides.

Nutrient recovery and recycling from fishery waste and by-products

The circular bio-based economy offers great untapped potential for the food industry as possible valuable products and energy can be recovered from food waste. This can promote more sustainable and resilient food systems in Europe in follow-up of the European Commission's Farm to Fork strategy and support the global transition to more sustainable agri-food systems with the common agricultural and fisheries policies. With its high nutrient content, waste and by-products originating from fish and seafood industry (including aquaculture) are one of the most promising candidates to produce alternative fertilising products which can play a crucial role to replace synthetic mineral fertilisers. Whereas several studies highlighted the opportunities to recover valuable compounds from fishery waste, study towards their potential for the production of fertilising products is still scarce. This study presents an extensive overview of the characteristics of fishery waste and by-products (i.e., fish processing waste, fish sludge, seafood waste/by-products), the state-of-the-art nutrient recovery technologies and recovered nutrients as fertilising products from these waste streams. The European Commission has already adopted a revised Fertilising Products Regulation (EU) 2019/1009 providing opportunities for fertilising products from various bio-based origins. In frame of this opportunity, we address the quality and safety aspects of the fishery waste-derived fertilising products under these criteria and highlight possible obstacles on their way to the market in the future. Considering its high nutrient content and vast abundance, fish sludge has a great potential but should be treated/refined before being applied to soil. In addition to the parameters currently regulated, it is crucial to consider the salinity levels of such fertilising products as well as the possible presence of other micropollutants especially microplastics to warrant their safe use in agriculture. The agronomic performance of fishery waste-derived fertilisers is also compiled and reported in the last section of this review paper, which in most cases perform equally to that of conventional synthetic fertilisers.

Comprehensive review: by-products from surimi production and better utilization

Over 1 million MT of surimi is produced globally, which theoretically would generate approximate 2 million MT of solid by-products and more than 1 million MT of wash water. Utilization of the by-products has increasingly become interested based on their nutritional, economical, and environmental issues. Surimi by-products represent an important source of valuable compounds such as functional protein, collagen, gelatin, fish oil, peptides, minerals, and enzymes. Better utilization of the by-products would make the surimi industry sustainable and profitable. This review paper characterizes sources and composition of the solid by-products and wash water generated from the surimi production as well as factors related to extraction and processing techniques. In addition, the potential food applications are explored including specialty foods and snacks, flavor ingredients, bioactive ingredients, and functional ingredients. Moreover, an outlook summarizing the challenges and prospects on the utilization of surimi by-products is provided.

Sea Bass Side Streams Extracts Obtained by Pulsed Electric Fields: Nutritional Characterization and Effect on SH-SY5Y Cells

Fish side streams are an environmental and economic problem. In this work, pulsed electric fields (PEF) extraction was optimized and used as a new method for their valorization. Sea bass head, skin, viscera, and backbone were used. PEF technology (123-300 kJ/kg, 1-3 kV/cm) improved the extraction of proteins and antioxidant compounds from head and skin, but was not successful for viscera. SDS-PAGE showed that the protein molecular weight distribution was affected by the extraction process, revealing differences between the control and PEF extraction conditions. In addition, the extraction of macro-minerals and micro-minerals were also evaluated. The effect of PEF differed according to the matrix and the mineral studied. Heavy metals were also taken into account, studying the presence of As, Cd, Hg, and Pb in the extracts. PEF pre-treatment reduced the presence of As in skin, viscera, and backbone, ranging from 18.25 to 28.48% according to the matrix evaluated. The analysis of potential antioxidant bioactive peptides showed that the treatment of the sample directly influenced their variety. Additionally, the extracts obtained from the head were found to increase cell viability when tested on SH-SY5Y cells. In conclusion, PEF extraction can be a useful tool for the valorization of fish side streams.

Physicochemical, technofunctional, in vitro antioxidant, and in situ muscle protein synthesis properties of a sprat (Sprattus sprattus) protein hydrolysate

Introduction

Sprat (Sprattus sprattus) is an underutilized fish species that may act as an economic and sustainable alternative source of protein due to its good amino acid (AA) profile along with its potential to act as a source of multiple bioactive peptide sequences.

Method and results

This study characterized the physicochemical, technofunctional, and in vitro antioxidant properties along with the AA profile and score of a sprat protein enzymatic hydrolysate (SPH). Furthermore, the impact of the SPH on the growth, proliferation, and muscle protein synthesis (MPS) in skeletal muscle (C2C12) myotubes was examined. The SPH displayed good solubility and emulsion stabilization properties containing all essential and non-essential AAs. Limited additional hydrolysis was observed following in vitro-simulated gastrointestinal digestion (SGID) of the SPH. The SGID-treated SPH (SPH-SGID) displayed in vitro oxygen radical antioxidant capacity (ORAC) activity (549.42 μmol TE/g sample) and the ability to reduce (68%) reactive oxygen species (ROS) production in C2C12 myotubes. Muscle growth and myotube thickness were analyzed using an xCELLigence™ platform in C2C12 myotubes treated with 1 mg protein equivalent.mL^-1 of SPH-SGID for 4 h. Anabolic signaling (phosphorylation of mTOR, rpS6, and 4E-BP1) and MPS (measured by puromycin incorporation) were assessed using immunoblotting. SPH-SGID significantly increased myotube thickness (p < 0.0001) compared to the negative control (cells grown in AA and serum-free medium). MPS was also significantly higher after incubation with SPH-SGID compared with the negative control (p < 0.05).

Conclusions

These preliminary in situ results indicate that SPH may have the ability to promote muscle enhancement. In vivo human studies are required to verify these findings.

Trends in fisheries waste utilization: a valuable resource of nutrients and valorized products for the food industry

The rise in fisheries production worldwide has caused a remarkable increase in associated anthropogenic waste. This poses significant concerns due to adverse environmental impacts and economic losses. Owing to its renewability, high abundance, and potential as a rich source of many nutrients and bioactive compounds, strategies have been developed to convert fish waste into different value-added products. Conventional and improved methods have been used for the extraction of biomolecules from fish waste. The extracted fish waste-derived value-added products such as enzymes, peptides, fish oil, etc. have been used to fortify different food products. This review aims to provide an overview of the nature and composition of fish waste, strategies for extracting biomolecules from fish waste, and the potential application of fish waste as a source of calcium and other nutrients in food fortification and animal feed has been discussed. In context to fishery waste mitigation, valorization, and circular bioeconomy approach are gaining momentum, aiming to eliminate waste while producing high-quality value-added food and feed products from fishery discards.

Mineral Bioaccessibility and Antioxidant Capacity of Protein Hydrolysates from Salmon (Salmo salar) and Mackerel (Scomber scombrus) Backbones and Heads

Information on the bioaccessibility of minerals is essential to consider a food ingredient as a potential mineral fortifier. In this study, the mineral bioaccessibility of protein hydrolysates from salmon (Salmo salar) and mackerel (Scomber scombrus) backbones and heads was evaluated. For this purpose, the hydrolysates were submitted to simulated gastrointestinal digestion (INFOGEST method), and the mineral content was analyzed before and after the digestive process. Ca, Mg, P, Fe, Zn, and Se were then determined using an inductively coupled plasma spectrometer mass detector (ICP-MS). The highest bioaccessibility of minerals was found in salmon and mackerel head hydrolysates for Fe (≥100%), followed by Se in salmon backbone hydrolysates (95%). The antioxidant capacity of all protein hydrolysate samples, which was measured by Trolox Equivalent Antioxidant Capacity (TEAC), increased (10-46%) after in vitro digestion. The heavy metals As, Hg, Cd, and Pb were determined (ICP-MS) in the raw hydrolysates to confirm the harmlessness of these products. Except for Cd in mackerel hydrolysates, all toxic elements were below the legislation levels for fish commodities. These results suggest the possibility of using protein hydrolysates from salmon and mackerel backbones and heads for food mineral fortification, as well as the need to verify their safety.

Collagen, protein hydrolysates and chitin from by-products of fish and shellfish: An overview

Waste processing from fish and seafood manufacturers represents a sustainable option to prevent environmental contamination, and their byproducts offer different benefits. Transforming fish and seafood waste into valuable compounds that present nutritional and functional properties compared to mammal products becomes a new alternative in Food Industry. In this review, collagen, protein hydrolysates, and chitin from fish and seafood byproducts were selected to explain their chemical characteristics, production methodologies, and possible future perspectives. These three byproducts are gaining a significant commercial market, impacting the food, cosmetic, pharmaceutical, agriculture, plastic, and biomedical industries. For this reason, the extraction methodologies, advantages, and disadvantages are discussed in this review.

Food Peptides for the Nutricosmetic Industry

In recent years, numerous reports have described bioactive peptides (biopeptides)/hydrolysates produced from various food sources. Biopeptides are considered interesting for industrial application since they show numerous functional properties (e.g., anti-aging, antioxidant, anti-inflammatory, and antimicrobial properties) and technological properties (e.g., solubility, emulsifying, and foaming). Moreover, they have fewer side effects than synthetic drugs. Nevertheless, some challenges must be overcome before their administration via the oral route. The gastric, pancreatic, and small intestinal enzymes and acidic stomach conditions can affect their bioavailability and the levels that can reach the site of action. Some delivery systems have been studied to avoid these problems (e.g., microemulsions, liposomes, solid lipid particles). This paper summarizes the results of studies conducted on biopeptides isolated from plants, marine organisms, animals, and biowaste by-products, discusses their potential application in the nutricosmetic industry, and considers potential delivery systems that could maintain their bioactivity. Our results show that food peptides are environmentally sustainable products that can be used as antioxidant, antimicrobial, anti-aging, and anti-inflammatory agents in nutricosmetic formulations. Biopeptide production from biowaste requires expertise in analytical procedures and good manufacturing practice. It is hoped that new analytical procedures can be developed to simplify large-scale production and that the authorities adopt and regulate use of appropriate testing standards to guarantee the population's safety.

Understanding fish waste management using bibliometric analysis: A supply chain perspective

Food loss and waste have become an issue of global significance, considering their concurrent effects on the socioeconomic and environmental facet of society. Despite this domain gaining prolific attention recently, issues hampering the effective utilization of residues from fish processing usually go unidentified in developing economies such as India. This occurs mainly owing to fragmented supply chains, inappropriate handling, discontinuous cold chains, inadequate temperature monitoring and so on, affecting quality and causing underuse. Any researcher trying to understand the prospects of utilizing these fish processing co-streams in a developing economy with the vision of improving consumption, economic sustainability, reducing discards and promoting circularity faces a lacuna. The authors address this demand in research by identifying the validity of this domain both in the global and native research community by conducting a detailed review using bibliometric analysis and content analysis. Data from Scopus with 717 documents, comprising 612 research articles from 78 countries, 1597 organizations and 2587 authors, are analysed. Results signify (i) developing a focus on hydroxyapatite production, bio-methane generation, transesterification processes, biomass and the rest raw material generated from fish processing, and (ii) reduced research on supply chain-related aspects despite their considerable importance. To comprehend this deficiency, especially in the Indian stance, barriers hindering the utilization of generated by-products are identified, and recommendations for improvements are proposed. The results will provide the struts for a circular and sustainable supply chain for processed seafood in developing economies.

Eco-friendly preparation and characterization of bioplastic films made from marine fish-scale wastes

Synthetic plastics are becoming hazardous wastes, posing a threat to environmental sustainable health; hence, they must be replaced with alternatives. This study aimed to prepare corn starch-based bioplastics using fish scale through film casting technique as an alternative to synthetic plastics. In this work, four types of bioplastic films (CSF, CSFSF1, CSFSF2, FSF) containing different percentages of fish-scale powder and corn starch were prepared. Physical and chemical properties such as texture, color, solubility in hot water, tensile strength, functional groups, and morphology of all the four types of the prepared bioplastics were analyzed. The mixture of fish-scale powder and corn starch powder in the ratio of 1:3 (CSFSF1) yielded the best results. Its average thickness is 0.0420 ± 0.001 mm, water absorption range is 55-60%, tensile strength is 6.06 ± 0.05 MPa, and thermal stability is 278.741 °C. In the biodegradability test, degradation was noticed after 7 days of treatment with organic waste. The degradation was confirmed by surface changes in the morphology and the development of Aspergillus sp. Corn starch film (CSF) exhibited the highest degradation (60%), while the fish-scales film (FSF) underwent the least degradation (28%). The produced bioplastics were prepared from eco-friendly, inexpensive, and natural materials. Thus, the present research has provided a viable alternative to synthetic plastics.

Fish By-Products: A Source of Enzymes to Generate Circular Bioactive Hydrolysates

Fish viscera are usually discarded as waste, causing environmental problems, or as low-value by-products. This study describes a self-sufficient and zero waste approach to obtain enzymes and protein hydrolysates from fish by-products. Firstly, recovery steps of viscera enzymatic extract were applied, and the resulting raw extract was stable at a pH range of 8-9 and at temperatures between 40 and 50 °C. The application of the extracted enzymes and alcalase on fish by-products hydrolysis was also determined. The selected conditions for the enzymatic hydrolysis were 10% (E/S) for 6 h using viscera enzymatic extract and 3% (E/S) for 2 h using alcalase. Fish protein hydrolysates (FPH) proved to have a notable antioxidant capacity with similar activity, ~11 mg ascorbic acid/g dry extract (ABTS assay) and ~150 mg Trolox/g dry extract (ORAC assay). FPH were also able to inhibit the angiotensin-converting enzyme, however, alcalase hydrolysates revealed a higher antihypertensive potential, IC₅₀ of 101 µg of protein/mL. In general, FPH obtained by both enzymes systems maintained these bioactivities after the passage throughout a simulated gastrointestinal tract. The hydrolysates also displayed important technological properties, namely oil absorption capacity (~1 g oil/g sample) and emulsifying property (~40%). Therefore, it will be conceivable to use fish by-products based on a circular economy approach to generate added value compounds for animal and human nutrition.

Transformation of Seafood Side-Streams and Residuals into Valuable Products

Seafood processing creates enormous amounts of side-streams. This review deals with the use of seafood side-streams for transformation into valuable products and identifies suitable approaches for making use of it for different purposes. Starting at the stage of catching fish to its selling point, many of the fish parts, such as head, skin, tail, fillet cut-offs, and the viscera, are wasted. These parts are rich in proteins, enzymes, healthy fatty acids such as monounsaturated and polyunsaturated ones, gelatin, and collagen. The valuable biochemical composition makes it worth discussing paths through which seafood side-streams can be turned into valuable products. Drawbacks, as well as challenges of different aquacultures, demonstrate the importance of using the various side-streams to produce valuable compounds to improve economic performance efficiency and sustainability of aquaculture. In this review, conventional and novel utilization approaches, as well as a combination of both, have been identified, which will lead to the development of sustainable production chains and the emergence of new bio-based products in the future.

Liposome System for Encapsulation of Spirulina platensis Protein Hydrolysates: Controlled-Release in Simulated Gastrointestinal Conditions, Structural and Functional Properties

This study aimed to evaluate the physicochemical, structural, antioxidant and antibacterial properties of chitosan-coated (0.5 and 1% CH) nanoliposomes containing hydrolyzed protein of Spirulina platensis and its stability in simulated gastric and intestine fluids. The chitosan coating of nanoliposomes containing Spirulina platensis hydrolyzed proteins increased their size and zeta potential. The fourier transform infrared spectroscopy (FT-IR) test showed an effective interaction between the hydrolyzed protein, the nanoliposome, and the chitosan coating. Increasing the concentration of hydrolyzed protein and the percentage of chitosan coating neutralized the decreasing effect of microencapsulation on the antioxidant activity of peptides. Chitosan coating (1%) resulted in improved stability of size, zeta potential, and poly dispersity index (PDI) of nanoliposomes, and lowered the release of the hydrolyzed Spirulina platensis protein from nanoliposomes. Increasing the percentage of chitosan coating neutralized the decrease in antibacterial properties of nanoliposomes containing hydrolyzed proteins. This study showed that 1% chitosan-coated nanoliposomes can protect Spirulina platensis hydrolyzed proteins and maintain their antioxidant and antibacterial activities.

Response Surface Modeling and Optimization of Enzymolysis Parameters for the In Vitro Antidiabetic Activities of Peanut Protein Hydrolysates Prepared Using Two Proteases

Optimization of the enzymolysis process for preparing peanut protein hydrolysates using alcalase and trypsin was performed by employing the central composite design (CCD) of response surface methodology (RSM). The independent variables were solid-to-liquid ratio (S/L), enzyme-to-substrate ratio (E/S), pH, and reaction temperature, while the response variables were degree of hydrolysate (DH), α-amylase, and α-glucosidase inhibitory activity. The highest DH (22.84% and 14.63%), α-amylase inhibition (56.78% and 40.80%), and α-glucosidase inhibition (86.37% and 86.51%) were obtained under optimal conditions, which were S/L of 1:26.22 and 1:30 w/v, E/S of 6% and 5.67%, pH of 8.41 and 8.56, and temperature of 56.18 °C and 58.75 °C at 3 h using alcalase (AH) and trypsin (TH), respectively. Molecular weight distributions of peanut protein hydrolysates were characterized by SDS-PAGE, which were mostly ˂10 kDa for both hydrolysates. Lyophilized AH and TH had IC₅₀ values of 6.77 and 5.86 mg/mL for α-amylase inhibitory activity, and 6.28 and 5.64 mg/mL for α-glucosidase inhibitory activity. The IC₅₀ of AH and TH against DPPH radical was achieved at 4.10 and 3.20 mg/mL and against ABTS radical at 2.71 and 2.32 mg/mL, respectively. The obtained hydrolysates with antidiabetic activity could be utilized as natural alternatives to synthetic antidiabetics, particularly in food and pharmaceutical products.

Effects of Mangosteen Peel Phenolic Compounds on Tilapia Skin Collagen-Based Mineralized Scaffold Properties

A proper valorization of biological waste sources for an effective conversion into composites for tissue engineering is discussed in this study. Hence, the collagen and the phenolic compound applied in this investigation were extracted from waste sources, respectively, fish industry rejects and the peels of the mangosteen fruit. Porous scaffolds were prepared by combining both components at different compositions and mineralized at different temperatures to evaluate the modifications in the biomimetic formation of apatite. The inclusion of mangosteen extract showed the advantage of increasing the collagen denaturation temperature, improving the stability of its triple helix. Moreover, the extract provided antioxidant activity due to its phenolic composition, as confirmed by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant assays. Mineralization was successfully achieved as indicated by thermogravimetry and scanning electron microscopy. A higher temperature and a lower extract concentration reduced the calcium phosphate deposits. The extract also affected the pore size, particularly at a lower concentration. The X-ray diffraction pattern identified a low degree of crystallization. A high mineralization temperature induced the formation of smaller crystallites ranging from 18.9 to 25.4 nm. Although the deposited hydroxyapatite showed low crystallinity, the scaffolds are suitable for bone tissue applications and may be effective in controlling the resorbability rate in tissue regeneration.

Characterization and Evaluation of Proteolysis Products during the Fermentation of Acid Whey and Fish Waste and Potential Applications

Reduction of waste in the food industry is critical to sustainability. This work represents one strategy of valorizing waste streams from the dairy (acid whey) and fisheries industries (fish waste) using fermentation. The main approach was to characterize the peptides produced by this fermentation under three conditions: (1) fermentation without adding inoculum; (2) with the addition of a single lactic acid bacterial strain; and (3) the addition of a consortium of lactic acid bacteria. Previous results indicated that the rapid acidification of this fermentation was advantageous for its food safety and microbial activity. This work complements our previous results by defining the rate of peptide production due to protein digestion and using two-dimensional (2D) gel electrophoresis and proteomic analysis to give a more detailed identification of the peptides produced from different waste streams. These results provide important information on this process for eventual applications in industrial fermentation and, ultimately, the efficient valorization of these waste streams.

Attenuation of allergenicity of roasted cod with Allium spp.: characterization of principal anti-allergenic constituent and action mechanism

Cod is rich in high-quality proteins and is a popular ingredient in many cuisines. However, it has also been a culprit in many seafood allergy cases. In the present study, the effect of pretreatment with Allium powders on the allergenicity and sensory profile of roasted cod was investigated. Enzyme-linked immunosorbent assay (ELISA) showed significantly reduced antibody-binding capacity of the Allium-pretreated samples compared with the control. The anti-allergenic effect was further confirmed with indirect ELISA using human sera. Moreover, the Allium pretreatments resulted in lower free sulfhydryl contents and higher surface hydrophobicity of the protein extracts prepared from the roasted cod samples, consistent with structural changes in favor of reduced allergenicity. Among the five Allium spp. evaluated, Chinese chive was the most effective, and mangiferin was identified to be a major anti-allergenic constituent. Docking simulation and mass spectrometry analyses revealed its strong parvalbumin-binding affinity and capability to reduce parvalbumin content in roasted cod, respectively. Finally, sensory evaluation indicated that the attenuation of allergenicity of roasted cod with the Allium spp. powders was accompanied by positive modulation of its flavor and taste profiles. These findings may provide insights for the development of dietary-phytochemical-based strategies for the management of parvalbumin-associated allergies.

Comparison of the molecular properties and volatile compounds of Maillard reaction products derived from animal- and cereal-based protein hydrolysates

The changes in the molecular properties and volatile compounds of Maillard reaction products obtained from chicken bone extract (CBE), wheat protein (WP), and rice protein (RP) hydrolysates were compared in this study. Pressure cooking was used to prepare CBE, which was then filtered, defatted, and concentrated. The optimum enzyme-substrate (E/S) ratio of CBE, WP, and RP on Flavourzyme® using the Michaelis-Menten model was 4.0, 5.7, 4.8% w/w, respectively. The occurrence of the Maillard reaction was demonstrated by the lowering of pH, low molecular weight peptides (<1K Da), and total free amino acids after the samples were heat-treated. Volatile compounds were analysed using gas chromatography-mass spectrometry (GC-MS) in conjunction with headspace solid-phase microextraction (SPME) sampling. Pyrazines, furan, and thioethers were detected in the MRPs of CBE, WP and RP. It was concluded that the MRPs of CBE, WP, and RP could be used as potential natural flavours in food applications.

Resource recovery from fish waste: Prospects and the usage of intensified extraction technologies

Globally, the valorization of fish biowaste as a feedstock to recover valuable components is an emerging research and commercial interest area to achieve the SDG goals by 2030. Fish waste-derived biomolecules are increasingly finding diverse applications in food and other biotechnological fields due to their excellent chemical, structural and functional properties. The focus of this review is to highlight the conventional valorization routes and recent advancements in extraction technologies for resource recovery applications, primarily focusing on green processes. Biointensified processes involving ultrasound, microwave, sub- and supercritical fluids, pulsed electric field, high-pressure processing, and cold plasma are extensively explored as sustainable technologies for valorizing fish discards and found numerous applications in the production of functional and commercially important biomaterials. With challenges in recovering intracellular bioactive compounds, selectivity, and energy requirement concerns, conventional approaches are being relooked continuously in the quest for process intensification and sustainable production practices. Nonetheless, in the context of 'zero waste' and 'biorefinery for high-value compounds', there is immense scope for technological upgradation in these emerging alternative approaches. This work details such attempts, providing insights into the immense untapped potential in this sector.

Impacts of pH and Base Substitution during Deaerator Treatments of Herring Milt Hydrolysate on the Odorous Content and the Antioxidant Activity

Despite the biological interest in herring milt hydrolysate (HMH), its valorization is limited by its unpleasant odor resulting from the presence of mainly amine and carbonyl compounds. Recently, a deaerator was demonstrated as an interesting avenue to reduce the odorous content of HMH. However, the removal rate of amine and carbonyl compounds was highly dependent on the operating conditions, and the impact of such a process on the biological potential of HMH was not considered. Therefore, this study aimed to optimize the deaerator process by assessing the impacts of the combination of deaerator treatments at neutral and basic pH, the increase in pH from 10 to 11, and the substitution of NaOH by KOH on the odorous content and the antioxidant activity of HMH. Results showed that the highest deodorization rate of HMH was obtained when a deaerator treatment at neutral pH was combined with another one at basic pH using KOH for alkalization. This condition resulted in a decrease in the dimethylamine and trimethylamine contents by 70%, while certain compounds such as 2,3-pentanedione, methional, (E,E)-2,4-heptadienal, or (E,Z)-2,6-nonadienal were almost completely removed. Removal mechanisms of the targeted compounds were totally identified, and the performance of the developed process was confirmed by sensory analysis. Lastly, it was shown that the antioxidant potential of HMH was not affected by the deodorization process. These results demonstrated the feasibility of deodorizing a complex matrix without affecting its biological potential.

Anti-Obesity Effect of Porcine Collagen Peptide in 3T3-L1 Adipocytes and High-Fat Diet-Fed Mice by Regulating Adipogenesis

Obesity is one of the most common diseases caused by an imbalance in the intake and expenditure of energy, and it is associated with various metabolic complications. This study aimed at investigating the anti-obesity effects and mechanisms of porcine collagen peptide (PCP) using 3T3-L1 preadipocytes and high-fat diet (HFD)-fed mice. The PCP treatment significantly inhibited the adipocyte differentiation and attenuated the mRNA expression of transcription factors (CCAAT/enhancer-binding protein alpha [C/EBPα] and peroxisome proliferator-activated receptor gamma [PPARγ]) and the lipogenic gene (fatty acid synthase [FAS]) expression in 3T3-L1 preadipocytes. In the in vivo study, HFD-fed mice were fed low- (1.5 g/kg body weight/day) and high- (4.5 g/kg body weight/day) PCP for 12 weeks and compared with the normal diet-fed group and HFD-fed control group. The PCP-fed groups showed significantly lower body weight gain, white fat weight gain, serum triglycerides, and adipocyte size compared with the HFD-fed group. The changes in body fat were associated with the upregulation of adiponectin and the downregulation of leptin, C/EBPα, PPARγ, and FAS. These results suggest that PCP has the potential to reduce obesity by suppressing adipogenesis and could be applied as a functional food material.

Bioactive Peptides: An Understanding from Current Screening Methodology

Bioactive peptides with high potency against numerous human disorders have been regarded as a promising therapy in disease control. These peptides could be released from various dietary protein sources through hydrolysis processing using physical conditions, chemical agents, microbial fermentation, or enzymatic digestions. Considering the diversity of the original proteins and the complexity of the multiple structural peptides that existed in the hydrolysis mixture, the screening of bioactive peptides will be a challenge task. Well-organized and well-designed methods are necessarily required to enhance the efficiency of studying the potential peptides. This article, hence, provides an overview of bioactive peptides with an emphasis on the current strategy used for screening and characterization methods. Moreover, the understanding of the biological activities of peptides, mechanism inhibitions, and the interaction of the complex of peptide–enzyme is commonly evaluated using specific in vitro assays and molecular docking analysis.

Physiological and Clinical Aspects of Bioactive Peptides from Marine Animals

Biological molecules in nutraceuticals and functional foods have proven physiological properties to treat human chronic diseases. These molecules contribute to applications in the food and pharmaceutical industries by preventing food spoilage and cellular injury. Technological advancement in the screening and characterization of bioactive peptides has enabled scientists to understand the associated molecules. Consistent collaboration among nutritionists, pharmacists, food scientists, and bioengineers to find new bioactive compounds with higher therapeutic potential against nutrition-related diseases highlights the potential of the bioactive peptides for food and pharmaceutic industries. Among the popular dietary supplements, marine animals have always been considered imperative due to their rich nutritional values and byproduct use in the food and pharmaceutical industries. The bioactive peptides isolated from marine animals are well-known for their higher bioactivities against human diseases. The physiological properties of fish-based hydrolyzed proteins and peptides have been claimed through in vitro, in vivo, and clinical trials. However, systematic study on the physiological and clinical significance of these bioactive peptides is scarce. In this review, we not only discuss the physiological and clinical significance of antioxidant and anticancer peptides derived from marine animals, but we also compare their biological activities through existing in vitro and in vivo studies.

Quality of red tilapia viscera oil (Oreochromis sp.) as a function of extraction methods

This study aimed to propose a simple and efficient heating-freezing method for oil recovery from red tilapia (Oreochromis sp.) viscera, suitable for industrial application and that does not affect its composition. Three methodologies for oil extraction were studied: a) direct heating (69 °C and 29 min) of samples followed by separation of the oil by decantation, b) direct heating with subsequent freezing and c) solvent extraction assisted by ultrasound. For the oil obtained by each methodology, the following factors were determined: peroxide and iodine values, oxidative stability index, yield percentages and fatty acid profile and, to evaluate the changes thereof, a thermal analysis by differential scanning calorimetry was performed. An oil extracted by centrifugation from fresh viscera was used as control. Results showed yields of 92,126%, 60,99% and 55,36% for the oil obtained by heating and freezing, heating and decanting and solvent extraction, respectively, the other evaluated parameters were similar among each other. The content of PUFA was not affected by heating when compared to the control oil, although a decrease was observed in the solvent extracted oil. This behavior was corroborated with the thermal analysis, which showed that the higher PUFA content, the lower the melting temperatures of the oils and the energy required for phase change. A principal component analysis allowed determining that while there are no differences in the abundance of fatty acids C20:1, 14:0, 18:0, 16:1 and C16:0, there are differences for fatty acids C18:1 and C18:2 depending on the method of extraction used in the oil obtention. The results of this study show that the heating-freezing extraction method is a good alternative for acquiring value-added products and facilitates their implementation in rural areas. Furthermore, allows obtaining a product with high content of polyunsaturated fatty acids (at least a third of the total content).

Sustainable processes for treatment and management of seafood solid waste

Seafood processing is an important economical activity worldwide and is an integral part of the food chain system. However, their processing results in solid waste generation whose disposal and management is a serious concern. Proteins, amino acids, lipids with high amounts of polyunsaturated fatty acids (PUFA), carotenoids, and minerals are abundant in the discards, effluents, and by-catch of seafood processing waste. As a result, it causes nutritional loss and poses major environmental risks. To solve the issues, it is critical that the waste be exposed to secondary processing and valorization for recovery of value added products. Although chemical waste treatment technologies are available, the majority of these procedures have inherent flaws. Biological solutions, on the other hand, are safe, efficacious, and ecologically friendly while maintaining the intrinsic bioactivities after waste conversion. Microbial fermentation or the actions of exogenously introduced enzymes on waste components are used in most bioconversion processes. Algal biotechnology has recently developed unique technologies for biotransformation of nutrients, which may be employed as a feedstock for the recovery of important chemicals as well as biofuel. Bioconversion methods combined with a bio-refinery strategy offer the potential to enable environmentally-friendly and cost-effective seafood waste management. The refinement of these wastes through sustainable bioprocessing interventions can give rise to various circular bioeconomies within the seafood processing sector. Moreover, a techno-economic perspective on the developed solid waste processing lines and its subsequent environmental impact could facilitate commercialization. This review aims to provide a comprehensive view and critical analysis of the recent updates in seafood waste processing in terms of bioconversion processes and byproduct development. Various case studies on circular bioeconomy formulated on seafood processing waste along with techno-economic feasibility for the possible development of sustainable seafood biorefineries have also been discussed.

Identification of black sturgeon caviar pigment as eumelanin

Reported herein is the purification of the pigment of black sturgeon caviar and its unambiguous identification as a typical eumelanin by means of chemical degradation coupled with electron paramagnetic resonance (EPR) evidence. HPLC and LC-MS analysis of oxidative degradation mixtures revealed the formation of pyrrole-2,3,5-tricarboxylic acid (PTCA), a specific marker of eumelanin pigments, in yields compatible with a 6.5% w/w pigment content. EPR spectral features and parameters were in close agreement with those reported for a typical natural eumelanin such as Sepia melanin from squid ink. The identification for the first time of eumelanin in a fish roe is expected to provide a novel molecular basis for the valorization of black caviar and production wastes thereof in food chemistry and diet.

Valorization of fish byproducts: Sources to end-product applications of bioactive protein hydrolysate

Fish processing industries result in an ample number of protein-rich byproducts, which have been used to produce protein hydrolysate (PH) for human consumption. Chemical, microbial, and enzymatic hydrolysis processes have been implemented for the production of fish PH (FPH) from diverse types of fish processing byproducts. FPH has been reported to possess bioactive active peptides known to exhibit various biological activities such as antioxidant, antimicrobial, angiotensin-I converting enzyme inhibition, calcium-binding ability, dipeptidyl peptidase-IV inhibition, immunomodulation, and antiproliferative activity, which are discussed comprehensively in this review. Appropriate conditions for the hydrolysis process (e.g., type and concentration of enzymes, time, and temperature) play an important role in achieving the desired level of hydrolysis, thus affecting the functional and bioactive properties and stability of FPH. This review provides an in-depth and comprehensive discussion on the sources, process parameters, purification as well as functional and bioactive properties of FPHs. The most recent research findings on the impact of production parameters, bitterness of peptide, storage, and food processing conditions on functional properties and stability of FPH were also reported. More importantly, the recent studies on biological activities of FPH and in vivo health benefits were discussed with the possible mechanism of action. Furthermore, FPH-polyphenol conjugate, encapsulation, and digestive stability of FPH were discussed in terms of their potential to be utilized as a nutraceutical ingredient. Last but not the least, various industrial applications of FPH and the fate of FPH in terms of limitations, hurdles, future research directions, and challenges have been addressed.