Search Results (364)

Protein hydrolysates (PHs) have emerged as a pivotal category of plant biostimulants in sustainable agriculture. They are derived from the enzymatic, chemical, or thermal hydrolysis of agro-industrial by-products of animal or plant origin. These complex mixtures of free amino acids, oligopeptides, and polypeptides enhance crop productivity, nutrient use efficiency, and abiotic stress resilience. This review examines and compares the production methods, chemical composition, agronomic performance, physiological mechanism, and safety profiles of animal-derived (A-PHs) and vegetal-derived (V-PHs) protein hydrolysates, with particular emphasis on hydrolyzed collagen (HC) as an emerging biostimulant. Furthermore, the specific physiological roles of proline in mediating plant stress tolerance and hydroxyproline-rich glycoproteins in maintaining cell wall integrity are evaluated. Animal-derived sources, including collagen, keratin, and fish by-products, are characterized by elevated glycine, proline, and hydroxyproline concentrations, amino acids with established roles in root architecture promotion, reactive oxygen species (ROS) scavenging, and osmotic adjustment under stress. Conversely, V-PH exhibit richer bioactive peptide profiles and superior environmental sustainability indices. Underlying mechanisms encompass hormone-like activities mimicking auxin and gibberellin signaling, transcriptional reprogramming of nitrogen assimilation pathways, antioxidant enzyme modulation, and rhizosphere microbiota stimulation. Full article

Sheep hemoglobin hydrolysate (SHH) has important biological antioxidant functions. However, the specific mechanism is not well understood. The aim of this study was to investigate the antioxidant activity of SHH in vivo and its potential mechanism. Eighteen Sprague Dawley rats were randomly divided into DG (gavaged with 0.9% saline), VC (gavaged with vitamin C 100 mg/kg BW) and SHH (gavaged with SHH 800 mg/kg BW) groups. The rats were given intragastric administration for 21 days. On the 22nd day, all rats were intraperitoneally injected with diquat as a challenge. The results showed that SHH treatment had no obvious effect on the growth performance and main organ index of rats after the diquat challenge. Compared to the DG group, the SHH group maintained higher serum T-AOC and GSH-Px levels after the diquat challenge. SHH significantly increased GSH-Px activity in the liver and kidney, and decreased MDA content in the kidney after the diquat challenge. SHH significantly up-regulated the gene expression of TrxR in the liver and Nrf2 in the kidney but had no significant effect on the expression of NF-κB in the kidney. Histopathological observations showed that SHH could improve the morphology of liver cells, and no obvious pathological damage was found in all organs. In conclusion, the relative decrease in oxidative stress markers observed with prophylactic SHH supplementation after diquat challenge may be mediated by the regulation of transcriptional expression of Nrf2-related redox genes. These findings demonstrate SHH’s potential as a natural antioxidant and provide promising strategies for converting low-value meat industry byproducts into functional supplements. Full article

Background/Objectives: Atopic dermatitis (AD) is a multifactorial inflammatory skin disorder in which epidermal barrier disruption and dysregulated immune responses drive persistent cutaneous inflammation. Owing to their broad spectrum of biological activities, marine-derived peptides have attracted increasing attention as potential therapeutic agents capable of modulating inflammatory and immune pathways. Methods: In this study, a novel peptide, WPN-15 (NGAIADQQPQRPNIV), was isolated from enzymatic hydrolysates of walleye pollock (Gadus chalcogrammus) tail by-products using an activity-guided purification process consisting of dialysis, fast protein liquid chromatography-gel permeation chromatography (FPLC-GPC), reverse-phase high-performance liquid chromatography (RP-HPLC), and electrospray ionization mass spectrometry (ESI-MS). The anti-inflammatory activity of WPN-15 was first examined in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages, and subsequently validated in a 2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis model using six-week-old male BALB/c mice. Results: WPN-15 significantly inhibited nitric oxide production in LPS-stimulated macrophages without causing cytotoxic effects. Topical administration of WPN-15 markedly alleviated DNCB-induced AD-like kin lesions, significantly reduced dermatitis severity scores, and decreased serum interleukin (IL)-6 levels. Histological evaluation further demonstrated that WPN-15 attenuated epidermal hyperplasia, dermal thickening, and mast cell infiltration. Furthermore, WPN-15 significantly downregulated the mRNA expression of IL-1β and IL-6 and inhibited signal transducer and activator of transcription 3 (STAT3) phosphorylation in skin tissues, indicating that its protective effects are mediated, at least in part, through the suppression of the IL-6/STAT3 signaling pathway. Conclusions: WPN-15 effectively attenuated inflammatory responses and pathological features associated with experimental AD. These findings demonstrate that walleye pollock tail by-products represent a valuable and sustainable source of bioactive peptides and support the potential application of WPN-15 as a marine-derived therapeutic candidate for the management of AD. Full article

Rainbow trout is produced in large quantities worldwide, generating substantial processing by-products, among which collagen-rich skin and bone require high-value utilization. Rainbow trout collagen peptides potentially exhibit antiplatelet activity based on structural similarity to reported antiplatelet fish collagen peptides, while their active peptide sequences and underlying mechanisms require investigation. In this study, rainbow trout skin collagen was hydrolyzed by neutral protease, yielding a hydrolysate with 70.52% inhibition of platelet aggregation at 4 mg/mL. The fraction with high antiplatelet activity, N2-2, was obtained via separation by ODS-C18 and Sephadex LH-20 chromatography, which was enriched in Gly, Pro, and Hyp residues and characterized by mild hydrophilicity and a moderate molecular weight. Peptide sequences in the N2-2 were identified by HPLC-MS/MS, followed by molecular docking-based screening, and the four peptides selected were synthesized and evaluated for antiplatelet activity in vitro. Peptides MTGP and OOGGHG exhibited higher antiplatelet activity, with IC₅₀ values of 0.52 mM and 0.54 mM, respectively. Molecular docking indicated that MTGP and OOGGHG stably bind to the P2Y12 receptor via hydrogen bonding with key residues (Lys280, Arg256, and Asn191), with hydrophobic interactions contributing to complex stability. This study adds support to the feasibility of natural antiplatelet functional foods from rainbow trout collagen. Full article

Lentinus edodes stipe is an under-utilised processing by-product that holds potential as a natural umami source. This study systematically compared nine enzymatic hydrolysis combinations, including single proteases, cellulase, and double enzyme systems comprising both protease–protease and protease–cellulase mixtures, to optimise the release of taste-active and volatile flavor compounds from the stipes. The Flavourzyme-only hydrolysate achieved the highest degree of hydrolysis (50.38%), the richest 5′-nucleotides (5.46 mg/g), free amino acids (59.06 mg/g) and volatile compounds (150.23 μg/kg), and an equivalent umami concentration of 288 g monosodium glutamate equivalent per 100 g matter. It also delivered the strongest umami taste and the lowest bitterness in sensory evaluation. The double-enzyme systems consistently underperformed due to competitive substrate binding, suboptimal pH for companion enzymes, and potential mutual protease digestion. Among the volatile compounds, 1,2,4-trithiolane and cedrol were identified as key aroma differentiators by multivariate analysis. These findings demonstrate that Flavourzyme alone constitutes the optimal enzymatic system for producing clean-tasting, umami-rich condiments from L. edodes stipes and caution against indiscriminate enzyme blending without prior compatibility assessment. The optimized hydrolysis process provides a scalable route for the industrial valorisation of mushroom processing by-products. Full article

Tilapia (Oreochromis niloticus) scales represent an underutilized by-product with considerable potential as a source of bioactive peptides that can be released through enzymatic hydrolysis. This study evaluated the production of protein hydrolysates from demineralized tilapia scales using Alkaline Protease or Esperase 8.0 L^® (Alkaline Protease and Esperase 8.0 L® were kindly provided by Novozymes, Bagsværd, Denmark), and examined the impact of simulated gastrointestinal digestion (SGID) on their bioactivities. The highest degree of hydrolysis (DH) was obtained with Alkaline Protease (12.4%), generating peptide fractions predominantly below 1000 Da, with a major population around 888 Da. Both hydrolysates exhibited antioxidant activity, with the Alkaline Protease hydrolysate showing higher ferric reducing antioxidant power (FRAP) and Fe(II)-chelating activity. The hydrolysates also displayed significant angiotensin-converting enzyme (ACE) inhibitory activity (IC₅₀: 13–14 µg/mL), dipeptidyl peptidase IV (DPP-IV) inhibitory activity (IC₅₀: 0.66–0.69 mg/mL), and prolyl endopeptidase (PEP) inhibitory activity (IC₅₀: 0.63–0.72 mg/mL). The digests were non-cytotoxic at the concentrations tested (<10 mg/mL) in STC-1 enteroendocrine cells. Following SGID, increased ACE-inhibitory activity was observed, with IC₅₀ values as low as 4.6 µg/mL, whereas DPP-IV and PEP-inhibitory activities decreased. The intestinal digest of the Esperase hydrolysate also exhibited significant cellular antioxidant activity in the ROS assay. Overall, these results indicate that tilapia scale hydrolysates are a promising source of peptides associated with in vitro enzyme inhibitory and antioxidant activities. However, the specific bioactive peptides responsible for these effects were not identified. Therefore, further studies involving peptide characterization, bioavailability assessment, and in vivo validation are required to establish their physiological relevance and potential applications as functional ingredients. Full article

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

Drought represents one of the major constraints limiting maize productivity in southeastern Europe, particularly under non-irrigated conditions. This study evaluated the effectiveness of foliar biostimulants derived from animal collagen and keratin hydrolysates in mitigating drought stress and improving maize performance in southern Romania during a six-year field experiment (2020–2025). During the screening phase (2020–2022), four formulations (FM1, FM2, KC, and K2) were applied at two rates (5 and 10 L ha⁻¹) and compared with an untreated control. Significant effects of biostimulant formulation and dose were identified for plant height and grain yield (p < 0.001). Duncan’s multiple range test showed that K2 applied at 10 L ha⁻¹ achieved the highest mean grain yield (87.71 q ha⁻¹), significantly exceeding the untreated control (70.94 q ha⁻¹). Based on these results, K2 was selected for long-term validation during 2023–2025 and subsequently evaluated across the entire six-year experimental period. Mean grain yield increased from 52.06 q ha⁻¹ in the untreated control to 58.74 and 64.91 q ha⁻¹ following K2 application at 5 and 10 L ha⁻¹, respectively. Yield improvements were particularly pronounced during years characterized by severe precipitation deficits, when relative yield increases reached up to 41.9%. Economic analysis demonstrated positive net returns in all experimental years, with average profits of 108.6 EUR ha⁻¹ and 206.9 EUR ha⁻¹ for the 5 and 10 L ha⁻¹ application rates, respectively. The results demonstrate that keratin-based biostimulants derived from industrial by-products can improve maize productivity, enhance drought resilience, and contribute to circular-economy approaches in sustainable agriculture. Full article

Jackfruit seeds, a by-product of the jackfruit processing industry, comprise a substantial proportion of starch. As a result, jackfruit seeds are emerging as a viable source of fermentable sugars for fermentation processes. In this study, α-amylase from Bacillus licheniformis TKU004 was employed to hydrolyze gelatinized jackfruit seed starch slurry, and the hydrolysis conditions were systematically optimized using the Box–Behnken design (BBD) coupled with response surface methodology (RSM). Three independent variables, including incubation temperature (40–60 °C), enzyme-to-substrate ([E]/[S]) ratio (5–10 U/g), and reaction time (2–6 h), were evaluated, with dextrose equivalent (DE, %) as the response. The optimal hydrolysis parameters were determined to be 47 °C, an [E]/[S] ratio of 10 U/g, and a reaction time of 5.1 h, yielding a predicted DE of 31.72%. Experimental validation confirmed a DE of 32.85 ± 1.12%, in close agreement with the model prediction. HPLC (high-performance liquid chromatography) analysis of the hydrolysate revealed a composition of 14.20% glucose, 56.51% maltose, and 29.29% maltooligosaccharides, indicating that this process is well-suited for producing high-maltose syrup. In short, this study demonstrates the feasibility of valorizing jackfruit seed waste into value-added carbohydrate products through enzymatic hydrolysis with B. licheniformis α-amylase. 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

Gelatin capsule waste (GCW), a protein-rich by-product, represents a promising substrate for the generation of potential bioactive substances, including free amino acids and other soluble substances generated during enzymatic hydrolysis. In this study, gelatin hydrolysates with degrees of hydrolysis (DH) ranging from 10% to 40% were produced using the commercial enzymes NS AC0106 (endopeptidase) and NS AC0107 (aminopeptidase) to enhance their functional properties. Increasing DH significantly improved antioxidant activity, surface hydrophobicity, and emulsifying capacity (p < 0.05), while sterilization further enhanced antioxidant capacity. Structural analyses confirmed extensive protein degradation and conformational modifications, as evidenced by SDS–PAGE (formation of low-molecular-weight substances), FTIR (shifts in the amide I region), and NMR (release of free amino acids). Electronic tongue analysis indicated that enzymatic hydrolysis enhanced umami and salty taste attributes. Notably, hydrolysis using NS AC0107 at 40% DH resulted in the highest antioxidant activity, together with pronounced umami taste and low bitterness. Overall, GCW-derived hydrolysates show considerable potential as functional ingredients and provide a sustainable strategy for the valorization of protein-rich industrial by-products. Full article

Porcine blood meal is a protein and iron-rich animal by-product, but its use in companion animal diets is often limited by poor solubility and variable digestibility caused by thermal processing. This study evaluated whether enzymatic hydrolysis could improve the physicochemical properties, digestibility, iron-related characteristics, and antioxidant capacity of porcine blood meal for potential use in canine diets. Porcine blood meal was hydrolyzed using alcalase or pepsin under controlled conditions, and the resulting hydrolysates were characterized by degree of hydrolysis, electrophoretic peptide profiles, techno-functional properties, in vitro digestibility using a simulated canine gastrointestinal model, heme and non-heme iron fractions, and antioxidant activities. Alcalase treatment produced a higher degree of hydrolysis and more extensive peptide fragmentation than pepsin. Consistent with these structural changes, the alcalase hydrolysate exhibited significantly higher in vitro apparent digestibility. Enzymatic hydrolysis increased extractable heme iron while reducing ferrozine-reactive non-heme iron, suggesting changes in iron binding forms after proteolysis. Hydrolyzed samples also showed enhanced radical scavenging activity and ferric-reducing capacity, whereas superoxide dismutase (SOD)-like activity decreased following hydrolysis. These findings indicate that controlled enzymatic hydrolysis, particularly with alcalase, could improve apparent digestibility and non-enzymatic antioxidant capacity of porcine blood meal, supporting its potential as an iron-containing ingredient in canine diets. Further in vivo studies would be required to confirm iron availability and nutritional efficacy. 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

Mycoprotein production by Pleurotus salmoneostramineus was evaluated using the bread industry by-products wheat bran hydrolysate (WBH) and stale bread hydrolysate (SBH) as carbon sources, with mung bean protein hydrolysate (MBH) as a nitrogen source, within a circular bioeconomy framework. Enzymatic hydrolysis effectively converted these food industry waste streams into fermentable substrates with complementary nutritional profiles: SBH provided the highest total sugar content (57.53 g/L), while MBH contributed the highest total nitrogen (3.58 g/L) and essential amino acid content (215.05 mg/100 mL). Of 11 WBH:SBH ratio formulations evaluated under static cultivation, WB4 (WBH:SBH 70:30; C/N 27.32:1) was identified as the optimal carbon source formulation, producing the highest biomass (3.46 g/L) and protein content (23.19 g/100 g) after 14 days. Subsequent nitrogen source optimization under dynamic cultivation (200 rpm, 5 days) showed that MBH supplementation at 5 g/L produced the highest biomass (16.59 g/L), protein content (66.71 g/100 g), and absolute protein production (11.07 g/L). The amino acid profile of mycoprotein produced under optimized conditions met or exceeded the FAO/WHO-recommended essential amino acid requirements for older children, adolescents, and adults; the essential amino acid content (354.72 mg/g protein) was comparable to soy protein isolate and exceeded that of wheat gluten. Mycelial morphology shifted from filamentous networks under static conditions to fragmented clump structures under dynamic cultivation with MBH supplementation. These findings indicate the feasibility of producing nutritionally complete mycoprotein from food industry waste streams, with potential applications in plant-based food formulations. 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