By-product Protein Hydrolysate Research Articles

The effects of protein hydrolysates from rainbow trout by-products on growth, digestive and antioxidant enzymes, and liver lysozyme activity in sobaity (Sparidentex hasta) and Arabian yellowfin (Acanthopagrus arabicus) seabream juveniles

An eight-week feeding trial was conducted to elucidate the effects of rainbow trout by-products protein hydrolysates (FPH, 92 % peptides <1 kDa, ∼78.1 % crude protein, ∼2.7 % lipid) on growth and some selected physiological responses in sobaity (Sparidentex hasta) (1.7 ± 0.0 g) and Arabian yellowfin (Acanthopagrus arabicus) (0.9 ± 0.0 g) seabream. Fish meal in a basal diet (∼58 % crude protein, ∼12 % lipid) was replaced with FPH at four levels, including 0 (control), 1 % (FPH1), 2.5 % (FPH2.5), and 5 % (FPH5). Each experimental diet was offered thrice daily to fish in triplicate. At the end of the feeding trial, S. hasta fed with FPH diets showed positive linear and quadratic trends in growth performance, and those fed with FPH5 had the highest final weight (FBW; 9.8 ± 0.4) and better feed conversion ratio (FCR; 0.9 ± 0.0). Regarding A. arabicus it showed positive quadratic trend and fish fed FPH2.5 diet had the highest FBW (6.2 ± 0.3), and better FCR (1.2 ± 0.0) value. Trypsin and alkaline phosphatase (ALP) activities showed both positive linear and quadratic trends in S. hasta. In A. arabicus, both linear and quadratic trends were observed in the activities of trypsin and total proteases (P = 0.001), while positive quadratic trends in pepsin and ALP activities were noticed. Lysozyme activity significantly increased by supplementing the diet with FPH and showed both linear and quadratic trends in S. hasta, but it did not change in A. arabicus. Total antioxidant capacity (TAC) in A. arabicus increased and showed both linear and quadratic responses. The catalase and glutathione peroxidase activities in both species increased significantly in response to dietary FPH. This study showed that FPH effects in diet were species-specific and its supplementation levels at 2.5 and 5 % could be recommended in A. arabicus and S. hasta juveniles, respectively.

Flavor formation of tilapia byproduct hydrolysates in Maillard reaction.

The Maillard reaction (MR) of tilapia byproduct protein hydrolysates was investigated for the use of byproduct protein as a food ingredient and to mask its fishy odor and bitter flavor. The flavor differences in tilapia byproduct hydrolysates before and after the MR were analyzed to explore the key flavor precursor peptides and amino acids involved in MR. The results suggested that eight key volatile substances, including 2,5-dimethylpyrazine, 2-pentylfuran, hexanal, octanal, nonanal, (E)-2-decenal, decanal, and 1-octen-3-ol contributed most to the MR products group (ROAV>1). Ten volatile compounds, including 1-octen-3-ol, hexanal, 2-pentylfuran, 2,5-dimethylpyrazine, methyl decanoate, and 2-octylfuran, were the flavor markers that distinguished the different samples (VIP>1). The four most consumed peptides were VAPEEHPTL, GPIGPRGPAG, KSADDIKKAF, and VWEGQNIVK. Umami peptides and bitter free amino acids (FAAs) were the key flavor precursor peptide and FAAs, respectively. Overall, the hydrolysates of tilapia byproducts with flavor improved by MR are a promising strategy for the production of flavorings.

Enzymatic Preparation of Mushroom By-product Protein Hydrolysates (Mb-PPHs)

The excessive use of chemical fertilizers can cause severe environmental damage. In recent decades, the application of biostimulants to improve soil composition and stimulate plant growth has contributed significantly to environmental preservation. In this paper, we studied the production and characterization of an amino acid/peptide-enriched biostimulant using edible mushroom (Agaricus bisporus) by-products (tails and nonmarketable mushrooms) as raw materials and commercial proteases as hydrolytic agents. A single hydrolytic process using four different endoproteases, Alcalase®, L-450, Flavourzyme® or papain, and a sequential hydrolytic process using two proteases, an endoprotease and an exoprotease, Alcalase® + Flavourzyme® or L-450 + Flavourzyme), were conducted. A preevaluation of potential plant biostimulants was also carried out, testing the biostimulant capacity of single and sequential Mb-PPHs to stimulate maize seed germination and root growth, as well as the evaluation of the vigor index (VI), with very promising results.Graphical

Extraction of Novel Bioactive Peptides from Fish Protein Hydrolysates by Enzymatic Reactions

Bioactive peptides derived from fish the byproduct protein hydrolysate have wide potential as functional food ingredients. The preparation of bioactive peptides is commonly achieved via enzymatic hydrolysis; this is the most preferred method because it has high specificity, fewer residual organic solvents in the product, and it is usually carried out in mild conditions. The use of various enzymes such as proteases is widely practiced in the industry, yet there are various limitations as it is of high cost and there is a limited availability of food-grade enzymes in the market. Moreover, high-throughput purification and the identification analysis of these peptides are currently being studied to further understand the functionality and characterization of the bioactive peptides. This review mainly focuses on the novel bioactive peptides derived from fish protein hydrolysates from various fish wastes and byproducts. The hydrolysis conditions, source of hydrolysate, and amino acid sequence of these novel peptides are presented, along with their corresponding methods of analysis in purification and identification. The use of various enzymes yields novel peptides with potent bioactivities, such as antiproliferative, antimicrobial, antihypertensive, antiglycemic, antitumor, and antioxidative biological functions. The increasing interest in proteomics in marine and aquatic waste utilization continues due to these products’ bioactivity and sustainability.

Multivariate correlation of infrared fingerprints and molecular weight distributions with bioactivity of poultry by-product protein hydrolysates

• Processing conditions influence the bioactive properties of protein hydrolysates. • FTIR and SEC fingerprints are correlated with bioactivities of protein hydrolysates. • PLSR models predicted ACE-1 inhibition and DPPH radical scavenging activity. • FTIR-based models were observed to be more robust than SEC-based models. Characterization of protein hydrolysates is a vital step in developing peptide-based bioactive ingredients. Multivariate correlation of chemical fingerprints and bioactivity of poultry by-product protein hydrolysates is explored as a potential analytical strategy for characterization and quality control. Chemical fingerprints of sixty hydrolysates were acquired using Fourier-transform infrared spectroscopy (FTIR) and size exclusion chromatography (SEC). Bioactivities (2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and angiotensin-1-converting enzyme (ACE-1) inhibition) were measured in vitro . Partial least squares regression models based on FTIR fingerprints or SEC chromatograms showed a better prediction performance for ACE-1 inhibition (coefficients of determination (R 2 ) = 0.91, root mean square error of prediction (RMSECV) = 2.8; R 2 = 0.85, RMSECV = 3.5, respectively) than for DPPH radical scavenging (R 2 = 0.74, RMSECV = 0.3; R 2 = 0.75, RMSECV = 0.3, respectively). Such models are promising tools for rapid prediction of bioactivities and as a quality control technology in production of bioactive peptides.

Study on the mechanism of protein hydrolysate delaying quality deterioration of frozen surimi

The surimi processing industry generates a large number of underutilized by-products. The aim of this study was to evaluate the protein oxidation, protein degradation, and gel property of surimi during frozen storage to investigate the mechanism of cryoprotective effects of surimi by-product protein hydrolysates on surimi. The results showed that compared with Control and Cryoprotectant surimi, surimi by-product protein hydrolysates groups had lower thiobarbituric acid content, carbonyl content and surface hydrophobicity, higher Ca2+-ATPase activity, total sulfhydryl groups and salt-soluble proteins (P < 0.05), which significantly delayed the freezing denaturation and oxidation rate of surimi myofibrillar protein during frozen storage. Aggregation of surimi proteins occurred during frozen storage, and surimi by-product protein hydrolysates could inhibit the degradation of myofibrillar protein and effectively induce protein cross-linking, which led to the formation of a denser gel network in surimi. In summary, surimi by-product protein hydrolysates was expected to be a natural and green cryoprotectant and gel texture enhancer in surimi.

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 (&lt;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.

A Cholesterol Homeostasis by Bioactive Peptide Fraction from Pigeon Pea By-Product: An In-Vitro Study

In the mammalian’s cells, a higher level of plasma cholesterol is a risk factor for cardiovascular disease. Human 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) is a regulatory cholesterol synthesis enzyme in the mevalonate pathway. Statins are the major synthetic drugs as inhibitor of HMGCR but it’s associated with adverse effect so it is advisable to provide alternative therapeutic candidate for cholesterol homeostasis. The current investigation indicates the cholesterol-lowering effect of Pigeon pea by-product protein hydrolysate (PBPH) fraction by inhibition of HMGCR and cholesterol micelles. The PBPH fractions control the cholesterol levels by two ways, first, PBPH fractions (> 30 kDa and > 10 < 30 kDa) significantly block the recycling of bile salts to the hepatocyte cells with direct excretion via the digestive system. Second, PBPH fraction (< 10 kDa) exhibits inhibition of cholesterol micellar, as well as the catalytic domain of HMGCR in a dose dependant manner. The inhibition of HMGCR has been verified through HMGCR protein expression in the cholesterol synthesis pathway. The HMGCR protein shows significant up-regulation upon treatment with PBPH fraction < 10 kDa in HepG2 cells. The PBPH fraction shows potent inhibitory capacity on cholesterol homeostasis suggesting it to have hypocholesterolemic properties. It could find an admirable application for the development of functional foods.

Administration of Protein Hydrolysates from Anchovy (Engraulis Encrasicolus) Waste for Twelve Weeks Decreases Metabolic Dysfunction-Associated Fatty Liver Disease Severity in ApoE-/-Mice.

Simple SummaryMetabolic dysfunction-associated fatty liver disease (MAFLD) is an increasing concern worldwide. It currently represents the main cause of chronic liver disease in humans in Western countries. Nutritional strategies based on fish-rich diets are considered helpful in the prevention of MAFLD, and are also thought to be beneficial for human health. In particular, cholesterol- and triacylglycerol-lowering effects are associated with fish-derived proteins or hydrolysates. Our findings suggest that supplementing the diet with 10% (w/w) anchovy protein hydrolysates has an anti-obesity effect together with an improvement in lipid metabolism and a reduction in liver fat content and high-fat diet-induced liver disease. By virtue of their nutritional value and functional proprieties, anchovy by-product protein hydrolysates may be an efficient nutritional strategy in MAFLD prevention and treatment.Metabolic dysfunction-associated fatty liver disease (MAFLD) includes several diseases, ranging from simple steatosis to steatohepatitis, fibrosis and cirrhosis. Fish-rich diets are considered helpful in the prevention of MAFLD, and the enzymatic hydrolysis of fish waste has been explored as a means of obtaining high-value protein hydrolysates, which have been proven to exert beneficial bioactivities including anti-obesity and hypocholesterol effects. This study aimed to assess the effect of the administration of protein hydrolysates from anchovy waste (APH) for 12 weeks on attenuated high-fat diet-induced MAFLD in apolipoprotein E-knockout mice (ApoE–/–). Thirty ApoE–/– mice were divided into two groups (n = 15/group) and fed a high-fat diet (HFD), with and without the addition of 10% (w/w) APH. After 12 weeks, serum and hepatic lipid profiles, hepatic enzyme activities, liver histology and immunohistochemistry were analyzed to assess hepatic steatosis, inflammation and fibrosis. Twelve-weeks on a 10% (w/w) APH diet reduces total cholesterol and triglyceride serum levels, hepatic enzyme activity and hepatic triacylglycerol content (p < 0.0001), and results in a reduction in hepatic fat accumulation and macrophage recruitment (p < 0.0001). The results suggest that a 10% APH diet has an anti-obesity effect, with an improvement in lipid metabolism, hepatic steatosis and liver injury as a result of a high-fat diet. Protein hydrolysates from fish waste may represent an efficient nutritional strategy in several diseases, and their use as nutraceuticals is worthy of future investigation.

Effects of thermal processing on the flavor molecules of goat by-product hydrolysates

The aim of this study was to obtain flavor molecules from goat by-product hydrolysates, emphasizing the thermal action during processing. A mixture of by-products submitted or not to the inactivation of endogenous enzymes was used, followed by hydrolysis with the proteolytic enzyme Alcalase® (Bacillus licheniformis), and autoclaving after hydrolysis. The production of hydrolysates provided both quantitative and qualitative data on the precursors involved in the aromatic formation of protein hydrolysates. The inactivation process of endogenous enzymes resulted in hydrolysates with a higher degree of hydrolysis and greater protein content. The autoclaving process produced a significant increase in the concentration of free amino acids and maltose and a reduction in the glucose content. Application of the two heat treatments resulted in the production of goat by-product protein hydrolysates with different volatile profiles. The goat by-product protein hydrolysate without heat treatment but with autoclaving (HCA), showing a higher concentration of flavor precursors and the formation of heterocyclic volatiles, is expected to impact the aroma quality of goat hydrolysates.

Antioxidant and Enzyme Inhibitory Activities of Metapenaeus monoceros By-Product Hydrolysates Elaborated by Purified Alkaline Proteases

This study investigated the antioxidant potential and enzymatic inhibitory power of shrimp by-product protein hydrolysates (hyd) prepared using two purified serine alkaline proteases namely; alkaline protease from Anoxybacillus kamchatkensis strain M1V (SAPA) and alkaline protease from Aeribacillus pallidus strain VP3 (SPVP). The characterization of their molecular weights showed the presence of peptides less than 15 kDa. SAPA-hyd displayed the highest reducing power activity. Likewise, SAPA-hyd was found to be active against angiotensin I-converting enzyme (ACE), tyrosinase (Tyr), and amylase (Amy) enzymes with IC50 values of 10.01, 6.13, and 4.11 µg/mL, respectively. SPVP-hyd revealed the highest radical scavenging power, β-carotene protection, and ferrous chelating activity with EC50 values of 11.79, 3.69, and 0.61 µg/mL, respectively. After fraction nation, all fractions displayed a high inhibitory potential against ACE. Only fractions F2 and F3 from SAPA-hyd showed the highest anti-tyrosinase activity with IC50 values of 25.10 and 12.5 ng/mL, respectively. These results suggest that a simple, clean, economic, and controllable bioprocess for the utilization of shrimp by-product was investigated. This study gives an unprecedented report on the anti-Tyr activity of the protein hydrolysate from fish bio-waste. Additionally, two peptide hydrolysates with multifunctional biological activities were elaborated from Metapenaeus monoceros by two bacterial purified proteases.

Antiproliferative activity of protein hydrolysates derived from fish by-products on human colon and breast cancer cells.

AbstractThe consumption of fish is encouraged in dietary guidelines because of its association with health benefits; however, fish processing generates by-products (gills, bones, skin, head), which can rise up to 50–60% of fish weight after filleting. The investigation of bioactivity of fish by-products and subsequent utilization for the development of high added-value food ingredients and/or supplements will reduce waste and create new products of high nutritional value. We studied the antiproliferative activity of fish by-product protein hydrolysates (FPH) on human colon and breast cancer cells. A total of 6 Meagres “Argirosomus Regius” (1256.45 ± 232.32g) and 16 Gilthead Sea Breams “Sparus Aurata” (403.47 ± 72.92g) were obtained by HCMR Institute in Crete, Greece. The fins, skin, bones, head, and gills were isolated, lyophilized, homogenized and stored separately at -80oC. The protein hydrolysates from each byproduct were prepared using a pH extraction method. Human colorectal adenocarcinoma cells (COLO320 cells) and human breast adenocarcinoma cells (MCF7A cells) were treated with different FPH for 48 hours, and cellular proliferation was measured using the MTT assay. Results are given as mean percentage of triplicate independent analyses. Statistical significance of growth inhibition was estimated following Wilcoxon Signed-Ranks test with α = 0.05. In COLO320 cells, FPH induced a the significant antiproliferative activity at 0.5g/L. Specifically, FPH from bones, gills and skin of Meagre showed a growth inhibition of 23.7%, 9.9% and 26.4%, respectively, after 48 h of treatment. The inhibition by the same by-products from the Gilthead Sea bream was 24.6%, 21.9% and 26.4%, respectively after 48 h. In MCF7A cells, FPH exerted a significant growth inhibition at 1g/L. The skin and fins of Meagre induced a growth inhibition of 25.5% and 39.0% respectively; the gills, skin and fins of Gilthead Sea Bream showed a growth inhibition of 28.5%, 47.1% and 39.6%, respectively, after 48 h. These values were in the same range with etoposide (reference anticancer molecule) in the concentration of 3.1μM for COLO320 cells and 50μM for MCF7A. These preliminary data suggest that certain fish by-products could represent a source of anticancer peptides and may cause growth inhibition of human cancer cells. The isolation of responsible bioactive peptides from fish byproducts and the integration of them into food supplements can have beneficial effects on human health.

Effects of pressure-assisted enzymatic hydrolysis on functional and bioactive properties of tilapia (Oreochromis niloticus) by-product protein hydrolysates

Fish by-product protein can be converted into valuable food and nutraceutical ingredients via proteolysis. The existing process suffers from many limitations such as extended reaction time and nonselective hydrolysis. In this study, protein from tilapia fish by-products was transformed into functional peptides using pressure-assisted enzymatic hydrolysis. Proteins were extracted from the tilapia by-products by isoelectric solubilization and precipitation method. The effects of pressure (38–462 MPa) and hydrolysis time (6–35 min) on the properties of the hydrolysates were investigated using a central composite design. Pressure enhanced protein hydrolysis with a maximum trichloroacetic acid-solubility index (TCA-SI) of 23% obtained at 250 MPa for 35 min. Pressure and time were also vital in improving soluble protein content (5.7 mg/mL), reducing power (44 μg AAE/g), and solubility (71%) of the hydrolyzed products. Improved antioxidant activity, indicated by a significant decrease in IC50 values from 653 μg/mL to 304 μg/mL, was recorded. The combined process facilitated the release of low-molecular-weight peptides and essential amino acids. However, water and oil holding capacities were found to be decreased. Pressure-assisted enzymatic hydrolysis could provide an effective approach for recovering bioactive peptides from fish by-products for industrial applications.

Preparation Protein Hydrolysates from Fish by-product and Study Effected on Lettuce (Lactuca sativa L.) Growth, Yield, Quality and Enhanced Salt Tolerance

The experiment was carried out during the winter season 2019-2018 in Al-Hartha district, Basrah Governorate to study the effects of fish by-product prepared by Alcalase and Flavourzyme enzyme as a foliar application on lettuce (Lactuca sativa L.) yield and quality grown under salinity conditions. Fish by-product protein hydrolysate was spray-applied (3 and 6ml. L-1) additional to control treatment (spraying with water) referred to (T0-T4) at four (S4), six(S6) times after 20 days transplanting at10-day intervals. Randomized Complete Block Design (R.C.B.D.) was used as factorial experiment. Treatment means were compared by using Least Significant Differences (L.S.D.) at a probability of 0.05. The results showed that spraying with protein hydrolysates had a significant effect on most studied characters compared to control treatment. Results showed that foliar application with (T2) significantly increased the total leaves number, leaves area, carbohydrate ,proline, shoot fresh weight of plant, dry matter, total soluble solids (TSS %) and total yield additional to significantly decreased in nitrate contents, while foliar application with (T4) significantly increased in the plant height and stem height. The results showed that spraying six times (S6) were significant increases in these growth characters comparing with four sprays (S4). The interaction between treatments and spraying number show significantly increased in some characters, the (T2 S6) had the highest value shoot fresh weight 762.5g and total yield 17.899 tone.donum-1.

Physicochemical and Biological Properties of Eel By-Products Protein Hydrolysates: Potential Application to Meat Product Preservation

European eel by-products have been hydrolysed in order to produce novel bioactive peptides with antibacterial and antioxidant activity. Protein hydrolysates from Anguilla by-products obtained by treatment with Savinase® (PHAB-s) have high protein content than that produced with Protamex® (PHAB-p). Furthemore, both protein hydrolysates had a high percentage of essential amino acids. In addition, results indicated that PHAB-s and PHAB-p exhibited different degrees of antioxidant activities, evaluated by several antioxidant assays. Thus, PHAB-s displayed high antioxidant activity, in terms of DPPH-radical scavenging effect (IC50 = 5.2 mg/ml), β-carotene bleaching inhibitory effect (CI50 = 4.4 mg/ml) and metal chelating activity. At 10 mg/ml, PHAB-p showed the highest reducing power. Antibacterial activities of PHAB-s and PHAB-p were also evaluated. PHAB-s showed the most important inhibitory effects against seven bacterial species. The application of PHAB-s and PHAB-p on minced meat as preservative reduced the lipid oxidation and inhibited the microbial growth during chilled storage for 11 days.

Peptides from Fish By-product Protein Hydrolysates and Its Functional Properties: an Overview.

The inadequate management of fish processing waste or by-products is one of the major problems that fish industry has to face nowadays. The mismanagement of this raw material leads to economic loss and environmental problems. The demand for the use of these by-products has led to the development of several processes in order to recover biomolecules from fish by-products. An efficient way to add value to fish waste protein is protein hydrolysis. Protein hydrolysates improve the functional properties and allow the release of peptides of different sizes with several bioactivities such as antioxidant, antimicrobial, antihypertensive, anti-inflammatory, or antihyperglycemic among others. This paper reviews different methods for the production of protein hydrolysates as well as current research about several fish by-products protein hydrolysates bioactive properties, aiming the dual objective: adding value to these underutilized by-products and minimizing their negative impact on the environment.

Evaluation on performance of dead-end ultrafiltration membrane in fractionating tilapia by-product protein hydrolysate

Conversion of tilapia by-products through enzymatic hydrolysis is a promising alternative to produce a fish protein hydrolysate (FPH). Tilapia by-product (TB) protein hydrolysate consists of peptide mixtures in various sizes. Recovery of small-sized peptides is increasingly becoming a priority due to their special characteristics, which can provide an excellent physiological function. Ultrafiltration (UF) membrane is an effective and suitable tool for fractionating small size peptides in a large scale. The objective of this study was to evaluate the membrane performance based on the permeate flux and peptide transmission. The fractionation of TB protein hydrolysate was performed through a dead-end UF membrane (10 and 5 kDa) with the effect of stirring speed (0–600 rpm), pH (3, 5, 7, 8 and 9) and salt concentration (NaCl; 0 M, 0.2 M, 0.4 M, and 0.6 M) at varies pressure (1.0, 1.5, 2.0, 2.5 and 3.0 bar). It was found that the transmembrane pressure of 2.5 bar, stirring speed of 600 rpm, pH 8 and without addition of NaCl turned out to be the best parameters which gave permeate flux of 53 L/m2h (10 kDa) and 27 L/m2h (5 kDa), while for the peptide transmission, the value of 87.33% (10 kDa) and 36.11% (5kDa) was obtained. This study indicates that by adding salt, it has lowered the permeate flux and peptide transmission. Finally, through a well-controlled of operating and physicochemical parameters, it was possible to produce peptides with sizes lower than 1000 Da.

Evaluation of the Antioxidant Activity In Vitro and in Hippocampal HT-22 Cells System of Protein Hydrolysates of Common Carp (Cyprinus carpio) By-Product

ABSTRACTFish processing by-products may become more than 50% of the starting material. If mismanaged, these large quantities of discarded fish can create serious pollution problems and can also generate cost associated with their disposal. Enzymatic hydrolysis is one of the techniques that is currently being developed in order to recover and add value to these biomolecules. There is an increasing interest in natural antioxidants that are safer for consumers compared with synthetic antioxidants. In this study, common carp by-product was hydrolyzed using the enzymes Alcalase (A) and Protamex (P) to reach degrees of hydrolysis (DH) of 10 and 15%, respectively. Antioxidant capacity against peroxyl radicals (ACAP); 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging; and the measurement of intracellular reactive oxygen species (ROS) concentration after exposure to common carp protein hydrolysates were investigated. The results revealed that the hydrolysate A15 exhibited significantly (p < 0.05) higher antioxidant activity against the DPPH radical. A15 showed the highest in vitro antioxidant competence against peroxyl radicals, whereas P15 showed the lowest activity against peroxyl radicals (p < 0.05). Hydrolysates having the highest and the lowest in vitro antioxidant activity (A15 and P15, respectively) were selected for the determination of antioxidant activity in the HT-22 cells system. Measurement of intracellular ROS concentration revealed that P15 at the concentration of 1.25 mg/mL significantly (p < 0.05) reduced the intracellular ROS concentration. These results showed that common carp by-product protein hydrolysates are a source of antioxidant peptides with a high potential for food and pharmaceutical industries to develop new nutraceuticals and functional foods.

Shrimp processing by-products protein hydrolysates: Evaluation of antioxidant activity and application in biomass and proteases production

Protein hydrolysates were prepared from shrimp processing by-products (SPBP) using five proteolytic enzymes: trypsin, Alcalase®, crude enzyme extract from sardinelle (Sardinella aurita) viscera and enzyme preparations from Bacillus licheniformis NH1 and Aspergillus clavatus ES1. The obtained hydrolysates exhibited different degrees of antioxidant activities evaluated through three main tests: 1,1-diphenyl-2-picrylhydrazyl (DPPH)-scavenging activity, reducing power and β-carotene bleaching assays. Hydrolysates were also tested as nitrogen source for microbial growth and proteases production by Escherichia coli, Saccharomyces cerevisiae, B. mojavensis A21 and B. subtilis A26. The reached results showed that the SPBP protein hydrolysates (SPBPPHs) could be a promising alternative to currently available commercial nitrogen sources of other origins.

Biological value of shrimp protein hydrolysate by-product produced by autolysis

The current study aimed to determine the biological value of shrimp by-product protein hydrolysate (SPH) produced by enzymatic autolysis. The biological experiment was carried out using Wistar strain, male rats, recently weaned, divided into three groups of eight. The groups received protein-free, casein (control) and SPH (experimental) diets for 28 days. Body weight, food and water consumption, urine volume, protein efficiency ratio (PER), food efficiency ratio (FER), net protein ration (NPR), relative net protein ratio (RNPR), in vivo protein digestibility, apparent digestibility and biochemical parameters were analyzed. No significant differences were observed among groups regarding weight curves and weekly weight gain, except for during the fourth week, when the SPH group presented greater weight gain. The casein group presented statistically higher levels of consumption in the first weeks in comparison to the SPH group. Regarding PER, FER, NPR and RNPR, animals on the SPH diet obtained statistically higher values than those on the casein diet. SPH proved to be of high biological value, as the rats on this diet presented greater biological responses than those in the casein-controlled group. Thus, SPH should be further studied with respect to its potential for use as a supplement in the human diet.