Characterization of Fish Protein Hydrolysate from Tilapia (Oreochromis Niloticus) by-Product

A comprehensive investigation of the use of freeze concentration appro aches for the concentration of fish protein hydrolysates

Fish protein hydrolysates (FPH) are inherently unstable in their liquid form, necessitating either freezing or dewatering for stabilization. Gentle methods such as freeze concentration can be used to remove water, this can be achieved by freezing water in solution by decreasing the bulk temperature below freezing point and separating pure ice crystals from concentrated solution. This approach serves as an alternative to techniques like evaporation and reverse osmosis for concentrating solutions that have high water content, significant nutritional value, and thermolabile compounds. This is crucial as many bioactive compounds degrade when exposed to elevated temperatures. Another notable advantage of this technology is its potential to reduce energy consumption by up to 40% when integrated into the FPH drying process. Although this technology is currently industrialized primarily for juices, it can achieve concentrations of up to 60°Brix and manage viscosities up to 400 mPa.s. Numerous studies have been dedicated to enhancing design and processes, leading to a 35% reduction in the system's capital cost and a 20% reduction in energy consumption. Moreover, freeze concentration can synergize with other concentration techniques, creating more efficient hybrid processes. This review aims to introduce freeze concentration as a superior option for preserving fish protein hydrolysates, enhancing their stability, and maintaining their nutritional and bioactive qualities.

Enzyme-free method for preparation of sturgeon extracts with antioxidant, hepatoprotective and immune-enhancing functions

Sturgeon has a long lifespan and slow evolutionary rate due to their powerful endogenous antioxidant system. This work aimed to assess the in vitro and in vivo antioxidant activity of sturgeon extracts from both muscle and roe. The extraction process without enzyme hydrolysis is not only simple, but also can produce extracts with better free radicals scavenging abilities than enzymatic hydrolysates in both cellular and in vivo experiments. Moreover, in mouse models with liver injury and immunosuppression treatment, the sturgeon extracts demonstrated strong hepatoprotective and immune-enhancing functions, comparable to vitamin C and ginseng extract supplements, which were attributed to abundant antioxidant peptides of the extracts. The 15 isolated peptides exhibited diverse free radical scavenging ability. Therefore, the sturgeon extracts showed high potential to be applied in food and biomedical industries.

Molecular Interaction of Angiotensin-I Converting Enzyme (ACE) with Peptides Derived from Collagen Type i as Analogue for Tilapia By-Product Protein Precursor

The study aimed to investigate the molecular interaction of ACE-inhibitory peptides derived from collagen type I. Collagen type I alpha 1 and alpha 2 were used in this work was to analogue the tilapia by-product protein precursor for ACE-inhibitory peptides production. In silico production of ACE-inhibitory peptides derived collagen type I from BIOPEP was used to simulate peptide-ACE interaction using Autodock Vina. Most potent ACE-inhibitory tri-and di-peptides, Gly-Leu-Pro (GLP IC50 1.62 μM) and Cys-Phe (CF IC50 1.96 μM) derived alpha 1 and Leu-Gly-Pro (LGP IC50 0.72 μM), and Glu-Tyr (EY IC50 2.68 μM) derived alpha 2 were chosen from BIOPEP database. The hydrophobicity of the amino acids is suggested to contribute to bioactivity. These peptides inhibited the active sites of ACE at the C terminal residue. The zinc (II) interacted with all four peptides directly and indirectly. GLP and CY of alpha 1 could share a bond with His 383, His 387, and Glu 411 instead of directly binding to the zinc (II) atom. ACE has a zinc ion in its coordinates with His 383, His 387, and Glu 411. Alpha 2's LGP and EY were directly bound to Zinc (ii) atoms.

Modelling of the kinetics of red tilapia (Oreochromis spp.) viscera enzymatic hydrolysis using mathematical and neural network models

The present work modelled the enzymatic hydrolysis of red tilapia (Oreochromis spp.) viscera with Alcalase® 2.4 L in both 0.5 and 5 L reactors. The best conditions for the enzymatic hydrolysis were 60°C and pH 10. The product inhibited the enzymatic hydrolysis, and the enzyme deactivated following second-order reaction. K_M and K_p from a secondary plot of K_M^app as a function of inhibitor concentration, and k_2, p, and k_3 were found by non-linear regression. While the obtained parameters modelled the 0.5 L reactor well, it did not model the 5 L reactor, probably because of unconsidered fluid dynamics in the model. To have a better modelling, a neural network (tensorflow.keras.models module) was built and trained. The neural network modelled the enzymatic hydrolysis of red tilapia at several concentrations of substrate and enzyme. This result proved that neural networks are a powerful tool for modelling biological processes.

Protein Hydrolysates Derived from Animals and Plants—A Review of Production Methods and Antioxidant Activity

There is currently considerable interest on the use of animal, plant, and fungal sources in the production of bioactive peptides, as evidenced by the substantial body of research on the topic. Such sources provide cheap and environmentally friendly material as it often includes waste and by-products. Enzymatic hydrolysis is considered an efficient method of obtaining peptides capable of antioxidant activity. Those properties have been proven in terms of radical-scavenging capacity using the DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2-azinobis-(3-ethyl-benzothiazoline-6-sulphonic acid)), hydroxyl and superoxide radical methods. Additionally, the reducing power, ferrous ion-chelating (FIC), ferric reducing antioxidant power (FRAP), and the ability of the protein hydrolysates to inhibit lipid peroxidation have also been explored. The results collected in this review clearly indicate that the substrate properties, as well as the conditions under which the hydrolysis reaction is carried out, affect the final antioxidant potential of the obtained peptides. This is mainly due to the structural properties of the obtained compounds such as size or amino acid sequences.

The Impact of COVID-19 Pandemic on Seafood Safety and Human Health

The coronavirus disease (COVID-19) pandemic caused several negative impacts on global human health and the world’s economy. Food and seafood safety and security were among the principal challenges and causes of concern for the food industry and consumers during the spread of this global pandemic. This article focused on the effects of COVID-19 pandemic on potential safety issues with seafood products and their processing methods. Moreover, the potential impacts of coronavirus transmission through seafood on human health were evaluated. The role of authenticity, traceability, and antimicrobials from natural sources to preserve seafood and the possible interaction of functional foods on the human immune system are also discussed. Although seafood is not considered a principal vector of SARS-CoV-2 transmission, the possible infections through contaminated surfaces of such food products cannot be neglected. The positive effects of seafood consumption on possible immunity built up, and COVID-19 are also summarized.

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).

Chemometric evaluation of enzymatic hydrolysis in the production of fish protein hydrolysates with acetylcholinesterase inhibitory activity

Fish protein hydrolysates (FPH) obtained from industrial processing residues are sources of bioactive peptides. The enzymatic hydrolysis process is essential in obtaining specific bioactivities such as inhibition of the enzyme acetylcholinesterase (AChE). In this study the effect of different hydrolysis conditions on the properties of FPH to inhibit the enzyme acetylcholinesterase. A chemometric evaluation, based on a central composite rotatable design and principal component analysis, was applied to select hydrolysis conditions with best yield, degree of hydrolysis and acetylcholinesterase inhibition. Experimental design results for AChE inhibition were between 10.51 and 40.45% (20, 30 and 50 mg.mL^-1 of FPH), and three hydrolysis conditions were selected based on PCA evaluation. The amino acids profile, FTIR and AChE inhibition kinetics were evaluated. Results showed a mixed type of inhibition behavior and, the docking molecular analyzes suggest that the inhibition AChE occurred due to the basic amino acids, mainly by arginine.

Carangoides bartholomaei (Cuvier, 1833) stomach: a source of aspartic proteases for industrial and biotechnological applications

The viscera and other residues from fish processing are commonly discarded by the fishing industry. These by-products can be a source of digestive enzymes with industrial and biotechnological potential. In this study, we aimed at the extraction, characterization, and application of acidic proteases from the stomach of Carangoides bartholomaei (Cuvier, 1833). A crude extract from the stomachs was obtained and submitted to a partial purification process by salting-out, which obtained a Purified Extract (PE) with a specific proteolytic activity of 54.0 U⋅mg-1. A purification of 1.9 fold and a yield of 41% were obtained. The PE presents two isoforms of acidic proteases and a maximum proteolytic activity at 45 °C and pH 2.0. The PE acidic proteolytic activity was stable in the pH range of 1.5 to 7.0 and temperature from 25 °C to 50 °C. Purified Extract kept 35% of its proteolytic activity at the presence of NaCl 15% (m/v) but was totally inhibited by pepstatin A. Purified Extract aspartic proteases presented high activity in the presence of heavy metals such as Cd2+, Hg2+, Pb2+, Al3+, and Cu2+. The utilization of PE as an enzymatic addictive in the collagen extraction from Nile tilapia scales has doubled the process yield. The results indicate the potential of these aspartic proteases for industrial and biotechnological applications.

Fractionation of Tilapia By-Product Protein Hydrolysate Using Multilayer Configuration of Ultrafiltration Membrane

Production of small-sized peptides is significant because of their health benefits. Ultrafiltration (UF) membrane provides an effective fractionation of small-sized peptides on a large scale. Thus, the present study was aimed to evaluate the performance of multilayer UF membrane in fractionating tilapia fish by-product (TB) protein hydrolysate by observing the permeate flux, peptide transmission, and peptide distribution under different stirring speed, pH of feed solution, and salt concentration (NaCl). The fractionation process was carried out using a dead-end UF membrane system that consists of a stack of two membrane sheets with different (10/5 kDa) and similar (5/5 kDa) pore sizes in one device. The highest permeate flux (10/5 kDa–39.5 to 47.3 L/m2.h; 5/5 kDa– 15.8 to 20.3 L/m2.h) and peptide transmission (10/5 kDa–51.8 to 61.0%; 5/5 kDa–18.3 to 23.3%) for both multilayer membrane configurations were obtained at 3.0 bar, 600 rpm, pH 8, and without the addition of salt. It was also found that the permeates were enriched with small-size peptides (<500 Da) with a concentration of 0.58 g/L (10/5 kDa) and 0.65 g/L (5/5 kDa) as compared to large-sized peptides (500–1500 Da) with concentration of 0.56 g/L (10/5 kDa) and 0.36 g/L (5/5 kDa). This might indicate the enrichment of small-size peptides through the multilayer membrane which could potentially enhance the biological activity of the protein hydrolysate fraction.

Tilapia viscera hydrolysate extract alleviates oxidative stress and renal damage in deoxycorticosterone acetate-salt-induced hypertension rats

Background and Aim:

Hypertension is closely related to oxidative stress conditions, which increases malondialdehyde (MDA) expression and renal damage. Tilapia viscera hydrolysate extract (TVHE) contains compounds and peptides that act as antioxidants. This study aimed to investigate TVHE therapy effect on MDA levels and renal histological conditions in deoxycorticosterone acetate (DOCA)-salt-induced hypertension rats.

Materials and Methods:

Tilapia viscera were defatted and hydrolyzed using Alcalase enzyme to obtain TVHE. TVHE antioxidant activity was measured using the 1,1-diphenyl-2-picrylhydrazyl method. Fifteen Wistar male rats were divided into five groups: Normal control (without induced DOCA-salt), DOCA-salt, DOCA-salt+Captopril 5 mg/kg body weight (BW), DOCA-salt+TVHE 150 mg/kg BW, and DOCA-salt+TVHE 300 mg/kg BW. MDA level and renal histology were observed in each group.

Results:

TVHE half maximal inhibitory concentration values ranged from 3.87±0.35 μg/mL to 42.03±3.55 μg/mL, which were identified as in the very strong Blois category. TVHE and captopril therapy reduced MDA expression significantly (p<0.05) compared to DOCA-salt only. TVHE and captopril therapy also improved glomerular damage in DOCA-salt-induced hypertension rats.

Conclusion:

TVHE has antioxidant ability, decreased MDA level, and decreased glomerular damage in DOCA-salt-induced hypertension rats.

Optimization of the Red Tilapia (Oreochromis spp.) Viscera Hydrolysis for Obtaining Iron-Binding Peptides and Evaluation of In Vitro Iron Bioavailability

Iron deficiencies continue to cause significant health problems in vulnerable populations. A good strategy to combat mineral deficiency includes fortification with iron-binding peptides. This research aims to determine the optimal conditions to hydrolyze red tilapia viscera (RTV) using Alcalase 2.4 L and recovery of iron-binding protein hydrolysate. The result showed that under the optimal hydrolysis condition including pH 10, 60 °C, E/S ratio of 0.306 U/g protein, and substrate concentration of 8 g protein/L, the obtained hydrolysate with 42.5% degree of hydrolysis (RTVH-B), displayed the maximal iron-binding capacity of 67.1 ± 1.9%. Peptide fractionation was performed using ultrafiltration and the <1 kDa fraction (FRTVH-V) expressed the highest iron-binding capacity of 95.8 ± 1.5%. Iron content of RTVH-B and its fraction was assessed, whereas iron uptake was measured indirectly as ferritin synthesis in a Caco-2 cell model and the result showed that bioavailability of bound minerals from protein complexes was significantly higher (p < 0.05) than iron salt in its free form, increased 4.7 times for the Fe2+-RTVH-B complex. This research suggests a potential application of RTVH-B as dietary supplements to improve iron absorption.

Valorization of Fish by-products: Purification of Bioactive Peptides from Codfish Blood and Sardine Cooking Wastewaters by Membrane Processing

Codfish blood and sardine cooking wastewaters were processed using membrane ultrafiltration that allowed for the preparation of bioactive peptides enriched fractions. The raw materials and corresponding permeates were characterized chemically and in terms of biological properties. The fractionation process was evaluated by analyzing the selective permeation of small peptides (<1 kDa) from larger compounds when using membranes with different molecular weight cut-offs (MWCOs) combined with different materials (MW, PW, and UP010 for codfish blood) and when operated at different transmembrane pressures (with GH for sardine cooking wastewaters). A rejection of the protein/peptides >10 kDa was achieved for both raw materials with the studied membranes. Also, low values of rejection of peptides <1 kDa were accomplished, namely 2% with UP010 from codfish blood and 23% when operated at minimum pressure (1.0 bar) with GH from sardine wastewaters. The peptide fractions from codfish blood with MW and UP010 exhibited the highest ABTS+ and ORAC values. Peptide fractions from sardine wastewaters with GH demonstrated no improvement in antioxidant activity compared to sardine wastewaters. The antimicrobial results showed that the peptide fractions from codfish blood with UP010 and from sardine with GH at 1.0 bar were capable of inhibiting Escherichia coli growth.

Nutrient Composition and Fatty Acid and Protein Profiles of Selected Fish By-Products

Processing of fish in aquaculture generates considerable amounts of by-products that remain underused and/or unexploited. We evaluated the nutritive content of fish by-products (head, gills, intestines, trimmings, bones, and skin) from meagre and gilthead sea bream fish species reared in Greece in order to estimate their nutritional value for future development of high added-value products. The proximate composition of the fish samples (total protein, total lipid, ash, moisture, and macro-element content) was determined using the Association of Official Analytical Chemists (AOAC) and International Organization for Standardization (ISO) official methods. The content of fatty acids was determined using capillary gas chromatography, and the protein profile was estimated employing scientific orbitrap mass spectrophotometer methodology. The nutrient composition of fish by-products presented fluctuations among the different by-products. Skin was the most significant protein source, trimmings and bones were high in calcium, and the head, intestines, and bones were a good source of lipids. The most abundant lipid acids found in by-products were oleic, palmitic, linoleic, and eicosenoic acids, whereas the most abundant proteins were adenosine triphosphate (ATP) synthase subunit epsilon, mitochondrial nicotinamide adenine dinucleotide (NADH) dehydrogenase, and mitochondrial cytochrome b-c1 complex subunit 8. These data suggest that by-products constitute valuable sources of nutrients and could therefore be exploited in accordance with the principles of a circular economy.

Enzymes in Fish and Seafood Processing

Enzymes have been used for the production and processing of fish and seafood for several centuries in an empirical manner. In recent decades, a growing trend toward a rational and controlled application of enzymes for such goals has emerged. Underlying such pattern are, among others, the increasingly wider array of enzyme activities and enzyme sources, improved enzyme formulations, and enhanced requirements for cost-effective and environmentally friendly processes. The better use of enzyme action in fish- and seafood-related application has had a significant impact on fish-related industry. Thus, new products have surfaced, product quality has improved, more sustainable processes have been developed, and innovative and reliable analytical techniques have been implemented. Recent development in these fields are presented and discussed, and prospective developments are suggested.