Search Results (190)

Marine by-products, including fishery discards, seafood-processing residues, aquaculture wastes, crustacean shells, and seaweed-derived side streams, are heterogeneous feedstocks rich in proteins, lipids, minerals, chitinous materials, polysaccharides, and bioactive compounds. This review examines insect-mediated bioconversion as a controlled biorefinery strategy for transforming these unstable marine residues into functional aquafeed ingredients and value-added bioproducts. We compare major marine feedstock classes and industrially relevant insects, with emphasis on substrate–insect matching, moisture control, salinity, lipid and ash load, texture, spoilage risk, and safety. Particular attention is given to how marine substrates can tailor insect meal, insect oil, chitinous fractions, hydrolysates, frass, and functional feed additives. The review further summarizes aquafeed applications of insect-derived products, including fishmeal and fish-oil replacement, protein and amino acid quality, lipid enrichment, gut health, immunity, and disease resistance in aquatic animals. Microbiome-assisted strategies, such as fermentation, enzymatic pretreatment, and gut or substrate microbial management, are discussed as tools to improve substrate stability, digestibility, and product quality. Finally, safety, regulation, scale-up, life cycle assessment, and techno-economic issues are considered. Overall, marine insect biorefineries should be optimized not only for biomass yield, but also for product quality, traceability, and application-specific safety. Full article

The replacement of fishmeal (FM) in aquafeeds for carnivorous fish remains challenging due to reduced palatability and adverse effects on liver health and intestinal microbiota. Marine by-products-based additives containing fish protein hydrolysates and seaweed polysaccharides have shown potential to overcome these limitations. This study evaluated the effects of graded supplementation of Haiweisu (HWS), a multi-marine by-product formulated with squid viscera hydrolysate, small-molecule components from fish protein hydrolysate, seaweed polysaccharides, and seaweed residue as a carrier, in a FM-free diet for juvenile largemouth bass. Four isonitrogenous and isolipidic diets were prepared: a FM-free control diet (CON) and three diets supplemented with 10, 20, or 30 g/kg HWS (designated S10, S20, and S30, respectively). Each diet was fed to triplicate groups of fish (29.26 ± 2.61 g) for 56 days. Results showed that HWS supplementation linearly increased final body weight, weight gain rate, and feed intake, while significantly reducing the feed conversion ratio (p < 0.05). All HWS-supplemented groups exhibited markedly lower hepatic lipid accumulation and plasma total cholesterol levels compared with the CON group, accompanied by alleviated hepatocellular steatosis and inflammatory infiltration as revealed by Oil Red O and H&E staining. Moreover, HWS significantly enhanced intestinal microbiota alpha diversity (Ace, Chao, Sobs, and Shannon indices), decreased the relative abundance of the dominant genus Mesomycoplasma, and enriched potentially beneficial genera including Methylobacterium, Delftia, and Sphingomonas (p < 0.05). In conclusion, dietary HWS supplementation effectively improved growth performance, alleviated hepatic steatosis and inflammation, and beneficially reshaped the intestinal microbiota in juvenile largemouth bass fed a FM-free diet. These findings support HWS as a promising functional additive for sustainable FM-free aquafeeds in carnivorous fish species. Full article

Large volumes of waste by-products are generated by the continuing growth of the fish production industry. To address this issue, this study valorized the protein hydrolysate extracted from fish waste for use as an active compound in a packaging system. An edible film was developed based on a chitosan/gelatin (CG) matrix, incorporated with fish protein hydrolysate (FPH) extracted from snakeskin gourami processing waste, at concentrations of 0%, 2%, 4%, 6%, and 8%. Introducing FPH into the film’s matrix enhanced the UV protection properties but decreased transparency. The incorporation of 4% FPH significantly increased the film tensile strength and antioxidant capacity by 47.67% and 65.04%, respectively, compared to the control, while concentrations of FPH exceeding 4% had a detrimental effect on film mechanical and antioxidant capacities. 4P-CG was identified as the optimal formulation and applied as an edible coating for sun-dried snakeskin gourami at 4 °C for 14 days. The 4P-CG coating preserved the quality of sun-dried fish by reducing weight loss and inhibiting microbial growth, which extended the shelf life by four days compared to the control (non-coated) and other CG-coated fish. These findings suggest that 4P-CG is a promising, sustainable active packaging solution for enhancing the stability and safety of fatty aquatic related products while contributing to the circular economy through waste reduction. Full article

Over the past decade, an increasing demand for natural antioxidants has driven research into antioxidant peptides and protein hydrolysates from fish and their processing by-products. Catfishes, especially species like Pangasius and Clarias, generate large amounts of protein-rich by-products, which represent a valuable bioresource for valorization. This review discusses advances from the past decade in the production, characterization, and antioxidant capacity of protein hydrolysates and peptides that have been discovered from catfish muscle and by-products. This review emphasizes enzymatic hydrolysis strategies, using Alcalase and other commercial and by-product-derived proteases. Potent antioxidant fractions, particularly those with low molecular weight (<3 kDa) and rich in hydrophobic/aromatic amino acids, have been obtained from the hydrolysates. Mechanisms of antioxidant action, which include hydrogen atom transfer and electron transfer, are discussed in this review, along with the efficacy of catfish-derived antioxidant peptides and protein hydrolysates as demonstrated in chemical and in vivo models. Applications in food systems, such as emulsion-type sausages, have shown potential for shelf-life extension. Nevertheless, knowledge gaps remain, which include an over-dependence on in vitro assays, limited identification of antioxidant peptide sequences, and insufficient data on sensory properties, intestinal permeability, bioavailability, and stability under food processing conditions. Future work should prioritize proteomic characterization, cellular validation, flavor-masking strategies, and scalable production protocols to accelerate the application of catfish protein hydrolysates as viable natural antioxidants for the functional food industry. Full article

This study investigated the replacement of squid-liver powder (SLP) with different marine protein hydrolysates in diets for Pacific white shrimp (Litopenaeus vannamei) over an eight-week feeding period. A control diet contained 5% SLP, whereas four test diets replaced 1% of the diet (dry-matter basis) with tuna hydrolysate liquid (TH), shrimp hydrolysate powder (SH), fish hydrolysate powder (FH), or salmon silage liquid (SS), with soybean meal adjusted to maintain dietary protein balance. Shrimp fed the TH diet showed higher final body weight (15.76 ± 0.24 g shrimp⁻¹) and specific growth rate (3.18 ± 0.02% day⁻¹) than those fed the other experimental diets (p < 0.05). TH also increased feed intake (20.96 ± 0.49 g shrimp⁻¹) and was associated with higher trypsin activity (3236 ± 226 unit h⁻¹ mg protein⁻¹) and improved protein digestibility. Histological observations indicated greater hepatopancreatic cell density and increased intestinal villus height in the TH group. In addition, survival of shrimp fed TH (90.0 ± 2.8%) was higher than that observed in the FH and SS groups (p < 0.05), and hemolymph from TH-fed shrimp showed stronger inhibitory activity against Vibrio parahaemolyticus. Overall, among the evaluated hydrolysates, 1% tuna hydrolysate (dry-matter basis) produced the most consistent improvements across growth performance, digestive capacity, and selected health-related indicators, supporting its feasibility as a partial substitute for squid liver powder in shrimp diets. Full article

Hypertension is a major controllable risk factor associated with cardiovascular disease, myocardial infarction, stroke, heart failure, and end-stage diabetes. While commercial antihypertensive drugs are effective in managing high blood pressure, they often come with a range of side effects. Additionally, individuals who begin anti-hypertensive treatment may need to continue these medications throughout their lifetime. In response to these challenges, recent studies have focused on the potential of antihypertensive peptides and hydrolysates derived from food proteins. Food protein-derived peptides and hydrolysates help lower blood pressure (hypertension) primarily by inhibiting the renin–angiotensin system (RAS). Some peptides or protein hydrolysates derived from milk and fish have been proven to be safe and effective anti-hypertensive products, and they are currently on the market. The bioactive peptides and hydrolysates derived from plant proteins with a long history of safe consumption are generally considered safe and have shown some advantages over animal protein-derived peptides. This review provides an up-to-date overview of plant protein-derived antihypertensive peptides and hydrolysates, covering their ACE- and renin-inhibiting activities and mechanisms, in vivo and clinical evidence, bioavailability, production and commercialization challenges, and perspectives for future research. Full article

This study evaluated protein hydrolysates from fish collagen (Col) and sheep keratin (Ker) as potential biostimulants in the hydro-priming of coriander (Coriandrum sativum L.) seeds. Seeds treated with low, non-nutritional doses of Col (0.5%) and Ker (1%) were compared with non-primed (C) and water-primed (H) controls under optimal conditions and after high-temperature stress (35 °C, 9 days). After stress removal, H-Col and H-Ker seeds achieved ~90% germination, whereas H and C reached 78% and 60%, respectively, confirming improved seed quality and post-stress recovery. Seedlings from Col- and Ker-treated seeds showed enhanced growth, higher biomass, and increased chlorophyll and precursor content. High-temperature stress also acted as a priming factor, modifying elemental profiles and stimulating carotenoid antioxidant synthesis. ATR–FTIR analyses indicated changes in cell wall composition and protein structure, particularly in the H-Ker variant. The results demonstrate that collagen and keratin hydrolysates, as industrial by-products, possess strong phytobiostimulatory potential and can be applied in sustainable strategies to improve seed quality and plant stress resilience. Full article

The invasive fish Atherina boyeri constitutes an ecologically disruptive yet underexploited biomass with strong potential for transformation into value-added biofunctional ingredients. This study investigates the functional, antioxidant, and antimicrobial properties of protein hydrolysates that were produced from fish collected in the Hirfanlı and Yamula reservoirs using three commercial proteases (alcalase, bromelain, and flavourzyme). Bromelain produced the highest degree of hydrolysis, yielding higher proportions of low-molecular-weight peptides and greater radical-scavenging activity. Flavourzyme hydrolysates exhibited the most favorable emulsifying properties, Alcalase hydrolysates produced the highest foaming capacity and stability. All hydrolysates showed high absolute zeta-potential values across pH 3–9, demonstrating strong colloidal stability. Protein solubility remained above 80% across most pH levels, indicating extensive peptide release and improved compatibility with aqueous media. The Oil-binding capacity (2.78–3.75 mL/g) was consistent with reported values for marine hydrolysates. Antioxidant and antimicrobial evaluations revealed clear enzyme-dependent patterns, with Bromelain exhibiting the strongest DPPH activity and Alcalase and Flavourzyme showing the most pronounced inhibition of major foodborne pathogens. Additionally, all hydrolysates exhibited measurable ACE-inhibitory activity, with flavourzyme-derived peptides showing the highest inhibitory activity, underscoring their potential relevance for antihypertensive applications. These findings highlight the strategic valorization of A. boyeri through enzymatic hydrolysis, demonstrating its potential as a sustainable, clean-label functional ingredient source. Full article

African catfish (Clarias gariepinus, AC) is one of the most widely farmed freshwater fish species in Central Europe. Processing operations generate up to 55% by-products (BPs), predominantly carcasses rich in proteins, lipids, and minerals. This study develops a comprehensive valorization process for ACBPs to recover gelatin, protein hydrolysate, fish oil, and pigments. The processing protocol consisted of sequential washing, oil extraction, demineralization, and biotechnological treatment to disrupt the collagen quaternary structure. A two-factor experimental design was employed to optimize the processing conditions. The factors included the extraction temperatures of the first (35–45 °C) and second fraction (50–60 °C). We hypothesized that enzymatic conditioning, combined with sequential hot-water extraction, would yield gelatin with properties comparable to those of mammalian- and fish-derived gelatins, while enabling a near-zero-waste process. The integrated process yielded 18.2 ± 1.2% fish oil, 9.8 ± 2.1% protein hydrolysate, 1.7 ± 0.7% pigment extract, and 25.3–37.8% gelatin. Optimal conditions (35 °C/60 °C) produced gelatin with gel strength of 168.8 ± 3.6 Bloom, dynamic viscosity of 2.48 ± 0.02 mPa·s, and yield of 34.76 ± 1.95%. Life cycle assessment (LCA) identified two primary environmental hotspots: water consumption and energy demand. This near-zero-waste biorefinery demonstrates the potential for comprehensive valorization of aquaculture BPs into multiple value-added bioproducts. Full article

The rapidly developing food industry necessitates the efficient use of raw materials, which can be achieved through the production of functional ingredients with high nutritional value. Secondary fish raw materials generated during the filleting of Atlantic cod (Gadus morhua), including vertebral bones with residual muscle tissue, skin, tails, and fins, represent a promising source of both biologically active compounds and highly digestible protein substances. The aim of this study was to evaluate the properties of protein hydrolysates obtained from secondary Atlantic cod raw materials by conventional enzymatic hydrolysis and combined enzymatic-ultrasonic treatment. The best results were achieved at a power of 320 W and a treatment duration of 3.5 min prior to the addition of the enzyme preparation (Protozyme C). The application of ultrasound enhanced the degree of hydrolysis by 4–5% while simultaneously reducing the amount of enzyme used. Electrophoretic analysis demonstrated a predominance of smaller peptides in the 10–15 kDa range compared to the control sample (43–95 kDa). Infrared spectroscopy confirmed structural changes in the samples under study, manifested in an increase in the number of terminal groups and partial disaggregation of the peptide mixture. Particle size distribution analysis revealed a more uniform distribution and a decrease in the median particle size in samples with ultrasonic pretreatment. The safety and antioxidant activity assessment did not show any toxic effects, but manifested a significant increase in antioxidant indicators (2.5–3.2 times) compared to the control sample. The results obtained show the enzymatic-ultrasonic treatment to be promising for the integrated processing of fish raw materials and the production of functional food ingredients with improved properties. Full article

An eight-week study was conducted to evaluate the effects of dietary marine protein hydrolysates as fish meal replacements in low-fish-meal diets on the growth performance, feed utilization, and health status of Asian seabass (Lates calcarifer). The high-fish-meal (HFM) diet contained 25% fish meal, while the low-fish-meal (LFM) diet replaced 60% of the fish meal with soybean meal. Three experimental diets were formulated by supplementing the LFM diet with 5% tuna hydrolysate (TH), 2% shrimp hydrolysate (SH), and 5% salmon silage (SS), each replacing an equivalent amount of fish meal. These diets were designated as LFM + TH, LFM + SH, and LFM + SS, respectively. The results showed that the LFM + TH diet significantly improved the percentage of weight gain, average daily growth, specific growth rate, protein efficiency ratio, and feed conversion ratio compared to the LFM diet (p < 0.05), without negatively affecting feed intake or metabolic markers. Histological analysis revealed improved villus length and goblet cell count in the intestine, indicating better nutrient absorption (p < 0.05). However, no significant differences were observed in hematological and immunological parameters, blood plasma metabolic markers, or carcass proximate composition (p > 0.05). Furthermore, the LFM + TH diet exhibited superior survival rates under ammonia stress, highlighting its potential to enhance stress tolerance. These findings suggest that marine protein hydrolysates, particularly 5%TH, can serve as a sustainable and efficient alternative to fish meal protein in diets with up to 60% in soybean meal compensation, promoting better growth and survival in Asian seabass. Full article

This study was conducted in two phases: first, to assess the impact of microbial fermentation on enhancing the nutritional quality of fish by-products, and second, to evaluate the effects of replacing fishmeal with these fermented by-products in the diet of Nile tilapia (Oreochromis niloticus) on growth performance, blood parameters, antioxidant indices, immunity, digestive enzyme activity, and carcass composition. In the initial phase, proteolytic activity of five bacterial strains including Bacillus subtilis (ATCC: 6051), B. licheniformis (IBRCM: 10204), Lactiplantibacillus plantarum (PTCCs: 1058 and 1745), and Lactobacillus casei (PTCC: 1608) was evaluated using growth assays in skimmed milk culture media and analyzed using Image-J software. B. licheniformis exhibited the highest proteolytic activity and was selected for fermentation. Resulting hydrolyzed proteins were characterized by peptides with molecular weights below 11 kDa. In the second phase, fishmeal was replaced with fermented by-products at five levels (0 (control), 25, 50, 75, and 100%). Two hundred ten Nile tilapia with an average weight of 2.83 ± 0.05 g were stocked in fifteen 200 L plastic tanks at three replicates, with 14 fish per tank, and fed daily at a rate of 7% of their body weight for 63 days. With increasing levels of fishmeal replacement (25% to 75%), significant improvements (p < 0.05) were observed in final weight gain, body weight gain, specific growth rate, protein production value, and protein efficiency ratio. Additionally, blood plasma concentrations of hormones T₃ and T₄, immunoglobulin level, the activities of complement (ACH₅₀), and antioxidant enzymes (catalase and superoxide dismutase) increased significantly in fish fed the diets with fermented by-products compared to those of the control diet (p < 0.05). The optimal replacement levels for specific growth rate and feed conversion ratio were identified as 86.28% and 83.91%, respectively. Full article

Valorisation of crab by-products by enzymatic hydrolysis (EH) is proving to be a promising strategy to promote sustainable aquaculture and support a circular economy for crustaceans. Crab processing generates significant amounts of by-products that, if not properly managed, pose an environmental and economic challenge. These by-products are rich in chitin, proteins, and bioactive compounds and offer significant untapped potential for the development of functional feed. This review focuses on the application of enzymatically hydrolysed crab by-products as functional feed additives in aquaculture and their effects on fish growth, health management, and, consequently, human health. Recent studies have shown that EH effectively recovers chitin and bioactive peptides and improves the digestibility and bioavailability of nutrients in aquaculture. The inclusion of crude chitin, along with residual proteins and calcium carbonate, in the diet of farmed fish has been associated with increased growth, improved immune responses, and greater disease resistance, emphasising their critical role in fish health management. In addition, these functional additives contribute to the development of innovative aquafeeds with high added value and improved nutritional quality, while reducing environmental waste. Overall, the utilisation of crustacean by-products through enzymatic hydrolysis represents a valuable tool for the sustainable development of crustacean aquaculture, promotes the circular economy, and supports the development of innovative functional feeds while improving the growth and health of farmed fish, which has a positive impact on human health through their consumption. Full article

The study presents the potential of milkfish frame, a by-product of milkfish processing, as a source of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides with potential applications in type 2 diabetes management. Proteomic analysis identified key proteins, including 65 kDa warm temperature acclimation protein 1 and myosin heavy chain. In silico prediction (BIOPEP-UWM) guided the selection of proteases for generating DPP-IV inhibitory peptides. Enzymatic hydrolysates were produced and evaluated for bioactivity. Among the treatments, pepsin hydrolysis (2% v/v, 8 h) yielded the highest peptide content (283.64 mg/g), soluble protein (86.46%), and DPP-IV inhibitory activity (68.47%). The resulting milkfish frame pepsin hydrolysate (MFH) was further enhanced through ultrafiltration and simulated gastrointestinal digestion, which improved the DPP-IV inhibitory and antioxidant capacities. Cytotoxicity assays confirmed that MFH (0–100 μg/mL) was non-toxic to FL83B hepatocytes after 24 h. Moreover, treating TNF-α-induced FL83B cells with 10 μg/mL MFHs improved cell viability, reducing the toxicity induced by TNF-α in cells. These findings show that MFHs exhibit promising antidiabetic potential and could serve as natural alternatives to synthetic drugs for type 2 diabetes management. This also demonstrates the valorization of fish processing by-products into functional food ingredients, advancing sustainable approaches in food innovation. Full article

Protein hydrolysates have potential as sustainable functional feed ingredients or additives for the aquaculture industry. This study examined the growth-promoting effects of duck-blood protein hydrolysate (DBPH, <10 kDa) on the flowerhorn cichlid (Amphilophus citrinellus × Cichlasoma trimaculatum). Fish with an average weight of 3.24 ± 0.22 g were randomly assigned to four dietary treatments: a negative control (basal diet) and basal diets supplemented with 0.5%, 1%, and 2% DBPH. After 90 days of the feeding trial, growth parameters indicated that supplementation with 1% and 2% DBPH enhanced growth. However, the muscle composition and skin coloration did not differ significantly. Transcriptome sequencing of the liver tissue yielded 39.83 GB of high-quality clean data. De novo transcriptome assembly identified 32,824 unigenes, of which 21,385 were successfully annotated based on public databases. Differential expression analysis identified 269 upregulated and 232 downregulated genes. To clarify the growth-promoting effects of DBPH, five glycolysis/gluconeogenesis-related genes (tpi, gapdh, pck1, ldh, and adh) were validated by liver qRT-PCR, and the results were consistent with those of the transcriptomic analysis. These findings provide new insights into the mechanisms by which DBPH supplementation could enhance growth, as evidenced by alterations in glycolysis and gluconeogenesis pathways, indicating potential as a novel feed additive in aquaculture. Full article