Influence of degree of hydrolysis on functional properties, antioxidant activity and ACE inhibitory activity of peanut protein hydrolysate

Chocolate desserts with ricotta hydrolysates: In vitro study of inhibitory activity against angiotensin-converting enzyme and cholinesterase

Food can be a source of valuable peptides with high bioactivity, which regulate the functioning of cardiovascular and nervous systems. The aim of the study was to evaluate the possibility of usage ricotta after hydrolysis to obtain innovative chocolate desserts. It was shown that the hydrolysis of whey proteins in ricotta had insignificant effect on the texture indices of the products, except gumminess, as it declined to 16% in ricotta samples and to 7% in case of chocolate dessert samples. Confirmed was that the hydrolysis of the ricotta affected the activity of prepared desserts with respect to cholinesterases and angiotensin-converting enzyme. Enzymatic hydrolysate of ricotta may be consider as a semifinished product of high functional activity, and its further application in dessert production allows to provide novel prohealth new products. PRACTICAL APPLICATION: Study results indicate new feasibilities of ricotta application as functional ingredient of new products--chocolate desserts. The results show that ricotta after the stage of enzyme hydrolysis of proteins might have noticeable effect on product functionality. A measurable benefit for the consumer is the receipt of a new product with favorable health-promoting properties, and for the entrepreneur new possibilities to expand the range of functional products. Moreover, described technology allows to use dairy byproducts for new products developments, such as chocolate desserts, due to sustainability development strategy.

Impact of Simulated Gastrointestinal Digestion on the Biological Activity of an Alcalase Hydrolysate of Orange Seed (Siavaraze, Citrus sinensis) by-Products

In this study, orange seed proteins were hydrolyzed by Alcalase enzyme at different enzyme concentrations 1-3% (v/w) and hydrolysis times (2-5 h), to obtain bioactive peptides showing antioxidant, Angiotensin-converting enzyme (ACE) -inhibitory, and hypoglycemic activities. The highest biological activities (p < 0.05) were achieved by using a hydrolysis time of 5 h and an enzyme concentration of 2%. Orange seed protein hydrolysate (OSPH) was prepared under these conditions, and peptides were isolated and purified by using size-exclusion chromatography and high-performance liquid chromatography, respectively. The fractions that showed the highest biological activities were analyzed by mass spectrometry in tandem, and a total of 63 peptide sequences were found. Moreover, the effect of simulated gastrointestinal digestion on the bioactivity of the fractions was studied, and the novel peptide sequences generated were also identified. Overall, despite there being some differences in the profile of peptide sequences obtained, the main results showed non-significant differences in the analyzed bioactivities after simulated gastrointestinal digestion.

Properties of Peanut (KAC431) Protein Hydrolysates and Their Impact on the Quality of Gluten-Free Rice Bread

Protein hydrolysates (PH) with a degree of hydrolysis (DH) of 5%, 10%, and 13% from two varieties of peanut were prepared using two commercial enzymes, Alcalase and Flavourzyme. The content of essential amino acids (30,290 mg/100 g) and hydrophobic amino acids (34,067 mg/100 g) of the peanut variety Kalasin 2 (KAC431) protein was higher than that of a common variety, Kalasin 1 (KAC1) (p < 0.05). The protein molecular weight distributions of the two varieties of peanut detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were similar, ranging from 15 to 75 kDa, with a major protein band at 50–75 kDa. The antioxidant and functional properties of derived PHs were influenced by DH. Although the foaming ability of protein was improved by DH5%, it was obviously decreased upon increasing DH further. The best emulsifying properties were observed in PH with DH5% (p < 0.05). The incorporation of PH with a small DH, especially when produced using Flavourzyme, had a highly positive impact on the specific volume and relative elasticity of gluten-free bread. The effect of PHs on bread quality was highly correlated with their functional properties. This study suggests that partially enzymatically modified proteins are suitable for incorporation in food products such as bread and other gluten-free products.

Partial Purification and Characterization of Bioactive Peptides from Cooked New Zealand Green-Lipped Mussel (Perna canaliculus) Protein Hydrolyzates

Proteins from fresh New Zealand green-lipped mussels were hydrolyzed for 240 min using pepsin and alcalase. The extent of the hydrolysis, antioxidant, antimicrobial, and angiotensin-converting enzyme (ACE) inhibitory activities of each protein hydrolysate were investigated. Peptides obtained from pepsin hydrolysis after 30 min, named GPH, exhibited the highest antioxidant and ACE inhibitory activity, but no antimicrobial activity. Purification of the GPH using gel-filtration chromatography revealed that the protein fraction (GPH-IV*) containing peptides with a molecular weight (MW) below 5 kDa had the strongest antioxidant and ACE inhibitory activities. Further purification was done using reverse-phase HPLC (RP-HPLC) and the only major peak obtained (GPH-IV*-P2) had the highest antioxidant and ACE inhibitory activity. From this fraction, several bioactive peptides with an MW ≈ 5 kDa were identified using LC-MS and in silico analyses. This research highlights that green-lipped mussel protein hydrolysates could be used as a good source of bioactive peptides with potential therapeutic applications.

Biological properties of almond proteins produced by aqueous and enzyme-assisted aqueous extraction processes from almond cake

The almond cake is a protein-rich residue generated by the mechanical expression of the almond oil. The effects of the aqueous (AEP) and enzyme-assisted aqueous extraction processes (EAEP) on the biological properties of the almond cake protein were evaluated. Total phenolic content (TPC), antioxidant capacity, inhibitory effects against crucial enzymes related to metabolic syndrome, antimicrobial potential, and in vitro protein digestibility profile were assessed. EAEP provided the best results for antioxidant capacity by both ORAC (397.2 µmol TE per g) and ABTS (650.5 µmol TE per g) methods and also showed a high (~ 98%) potential for α-glucosidase inhibition. The AEP resulted in protein extracts with the highest lipase inhibition (~ 70%) in a dose-dependent way. Enzymatic kinetic analyses revealed that EAEP generated uncompetitive inhibitors against α-glucosidase, while EAEP, AEP, and HEX-AEP (used as control) generated the same kind of inhibitors against lipase. No protein extract was effective against any of the bacteria strains tested at antimicrobial assays. An in silico theoretical hydrolysis of amandin subunits corroborated with the results found for antioxidant capacity, enzyme inhibitory experiments, and antimicrobial activity. Digestibility results indicated that the digestive proteases used were efficient in hydrolyzing almond proteins, regardless of the extraction applied and that HEX-AEP presented the highest digestibility (85%). In summary, EAEP and AEP skim proteins have the potential to be used as a nutraceutical ingredient. The biological properties observed in these extracts could help mitigate the development of metabolic syndrome where EAEP and AEP skim proteins could be potentially used as a prophylactic therapy for diabetes and obesity, respectively.

Physicochemical and emulsifying properties of mussel water-soluble proteins as affected by lecithin concentration

The effects of lecithin addition at different concentrations (0-2.0%) on the physicochemical and emulsifying properties of mussel water-soluble proteins (MWP) were investigated. In solution system, low lecithin concentration (0.5%-1.0%) induced the aggregation and increased turbidity of composite particles. Lecithin addition caused changes in secondary structure and induced partial unfolding of MWP. Hydrophobic interactions between MWP and lecithin may contribute to the exposure of chromophores and hydrophobic groups of MWP. The interfacial tension decreased with lecithin addition. However, at a high lecithin concentration (1.5%-2.0%), the degree of aggregation and state of unfolding alleviated due to competitive adsorption. In emulsion system, with the low concentration of lecithin addition (0.5%-1.0%), droplet size and surface charge of emulsion decreased. The emulsion activity index, emulsion stability index, percentage of adsorbed protein increased. Both creaming stability and viscoelastic properties improved. At an intermediate lecithin concentration (1.0%), the emulsion showed the highest physical stability, while further addition of lecithin caused a slight deterioration in emulsifying properties. Overall, these results indicated the possibility that the lecithin-MWP mixed emulsifiers can be used to obtain emulsions with desirable properties.

Enzymatically excised oligopeptides from Bellamya bengalensis shows potent antioxidative and anti-hypertensive activity

ABSTRACT

Bellamya bengalensis, an edible mollusca, serves as a protein rich food source for the tribes in India. The objective of the present study was to isolate the protein fraction of the edible foot part of B. bengalensis for hydrolysis with three proteases, namely papain, pepsin, and alcalase. B. bengalensis protein isolates and hydrolysates were characterised for the functional properties like protein solubility index, emulsifying property, foaming property. The proximate composition of the protein isolate was determined along with nutritional value that included biological value, protein efficiency ratio, amino acid score, nutritional index, essential amino acid index. The molecular weight distribution of the protein isolate and the three hydrolysates were analyzed by SDS-PAGE. The hydrolysates were fractionated by ultrafiltration and the in vitro antioxidative properties were measured. The antihypertensive property of the in vitro angiotensin converting enzyme inhibitory activity of the hydrolysates was compared with the standard drug lisinopril. Thus, the results indicated that the hydrolyzed peptides had potent antioxidative and antihypertensive activity. The enzyme pepsin and papain produced partially hydrolyzed peptides suitable for use in the bakery industry while alcalase hydrolysis resulted in shorter peptides with the antihypertensive activity that may be used as a promising nutraceutical.

GRAPHIC ABSTRACT

Oxidative Stability of Protease Treated Peanut with Reduced Allergenicity

Oxidative stability and allergenicity are two major concerns of peanuts. This study evaluated the impact of protease treatment of peanuts on its oxidative stability during storage. The raw and dry-roasted peanut kernels were hydrolyzed with Alcalase solution at pH 7.5 for 3 h. The contents of Ara h 1, Ara h 2, and Ara h 6 in peanuts were determined before and after enzyme treatment by a sandwich ELISA. After drying, the samples were packed in eight amber glass jars and stored at 37 °C for 1-8 weeks. Controls are untreated raw and dry-roasted peanuts packed and stored in the same way as their treated counterparts. Samples were taken biweekly to determine peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) as indicators of oxidation (n = 3), and to determine antioxidant activity. Alcalase treatment reduced intact major allergens Ara h 1, Ara h 2, and Ara h 6 by 100%, 99.8%, and 85%, respectively. The PVs of Alcalase-treated raw and roasted peanuts was lower than those of untreated (p < 0.05) over the 8-week storage. The TBARS of Alcalase-treated raw peanuts were slightly higher than that of untreated (p < 0.05), but the TBARS of Alcalase-treated dry-roasted peanuts were slightly but significantly lower than that of untreated (p < 0.05). The protease treatment increased the antioxidant activities including reducing power, DPPH free radical scavenging capacity, and metal chelating capacity of peanuts.

Phytochemical Compounds and Antioxidant Activity Modified by Germination and Hydrolysis in Mexican Amaranth

Amaranth (Amaranthus spp.) grains have become essential for human health and nutrition; due to the presence of bioactive compounds that have shown some biological activities. This study aimed to evaluate the effect of germination, enzymatic hydrolysis, and its combination on the phytochemical compounds and antioxidant activity in Mexican amaranth. Germinated amaranth flours (GAF) exhibited increases in the concentrations of soluble protein (SP), total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC) and antioxidant activity (AOX) by 35.7, 17.2, 163.0, 1472.2, and 54.3%, respectively, compared with ungerminated amaranth flours (UAF). In SDS-PAGE, both hydrolysates of UAF and GAF exhibited low molecular weight bands (< 10 kDa). The hydrolysates of UAFH and GAFH had the highest degree of hydrolysis at 205 min of sequential hydrolysis (pepsin with pancreatin) time with 73.4 and 60.3%, respectively. Both hydrolysates obtained from GAF and UAF released significantly SP, TPC, TFC after sequential enzymatic hydrolysis (up 205 min), which led to a remarkable improvement of AOX when compared to nonhydrolyzed amaranth samples. The UAFH and GAFH had the best AOX at 270 min of enzymatic hydrolysis with 983.1 and 1304.9 μmol TE/mg SP, respectively. Hence, the combination of germination and enzymatic hydrolysis could be used to produce functional ingredients for food product development.

Effect of Drying Temperatures on the Peanut Quality during Hot Air Drying

Peanuts are usually with high moisture after harvest and must be dried to prevent mildew. Hot air drying is the most commonly used method for peanut drying. The purpose of this study was to evaluate the drying temperatures on the peanut qualities. In this paper, fresh peanuts were dried with solar radiation (control group) and hot air at 35-60°C until the moisture content of peanut reduced below 10%. The physical (texture, damaged percentage of red testa and breakage percentage of peanut kernel), physiological (germination) and biochemical (the contents of vitamin E and aflatoxin B₁; acidity values, iodine values, peroxide values and fatty acid composition of peanut oil; solubility, emulsifying, foaming, water-holding capacity and oil-binding capacity of peanut protein) properties of peanut kernel were determined under different drying conditions (solar radiation, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C). The results showed that hot air temperatures had obvious influences on peanut qualities. The damaged percentage of red testa and breakage percentage of peanut kernel increased remarkably when the drying temperatures were above 45°C. Meanwhile, when drying temperatures were more than 45°C, the acid value and peroxide value of the extracted oil increased significantly. Furthermore, some properties exhibited prominent changes when the temperatures were higher than 50°C, such as hardness, brittleness, germination percentage, and the Vitamin E content of peanut kernel. In addition, the research results revealed that hot air can increase hydrophobicity of peanut protein and affect the functional properties of peanut protein. Therefore, it could be concluded that peanut should be dried by hot air below 45°C for quality maintenance. It also provided reference to choose suitable drying temperatures based on the final use of peanut.

Effects of partial hydrolysis on the structural, functional and antioxidant properties of oat protein isolate

The degree of hydrolysis (DH) plays important roles in the characteristics of food proteins. Herein, in order to explore the effects of partial hydrolysis on the structural, functional and antioxidant characteristics of hydrolysates, oat protein isolate was partially hydrolyzed with alcalase at different DHs (2%, 4%, 6%, 8%, 12%, and 16%). Our results showed that hydrolysis could induce significant structural changes in oat protein, mainly reflecting at the amino acid pattern, molecular weight profile and protein conformation. Alcalase hydrolysis also resulted in hydrolysates with the emulsifying activity index of at least 19.83 m2 g-1, and the highest emulsion stability was observed in the hydrolysate with a DH of 6%, possibly due to its suitable molecular weight, exposed hydrophobic amino acid residues and high surface net charge. Besides, all hydrolysates exerted excellent DPPH radical scavenging activity with an IC50 value ranging from 19.23 to 30.32 μg mL-1, which was closely correlated with DH. The oat protein isolate with moderate alcalase hydrolysis (DH 6%) exhibited the strongest metal ion-chelating activity and possessed the maximum amount of hydrophilic amino acids. More importantly, the oat protein hydrolysate with a DH of 6% not only prolonged the induction period of sunflower oil, but also improved the stability of the sunflower oil-in-water emulsion, as evidenced by the reduced TBARS production and the homogeneous droplet size. Therefore, partial hydrolysis can be advantageous for improving the functional and antioxidant characteristics of oat protein isolate, particularly the hydrolysate with a DH of 6%.

Anti-Hyperglycemic Effects of Green Crab Hydrolysates Derived by Commercially Available Enzymes

The predation and burrowing activity of invasive green crabs have had detrimental effects on important marine resources and habitats. Our objective is to develop bioactive hydrolysates by enzymatic proteolysis of underutilized green crab. Mechanically separated mince was hydrolyzed with Alcalase, Protamex, Flavourzyme, and Papain (1%) for 60 min. Subsequently, the hydrolysates were introduced to a simulated gastrointestinal digestion model. Selected samples were fractionated by ultrafiltration, and their anti-hyperglycemic effects including α-glucosidase, α-amylase, and dipeptidyl peptidase-IV (DPP-IV) inhibitory activities and glucagon-like 1 (GLP-1) secretory activity were evaluated. The Protamex treatment showed the highest α-glucosidase inhibitory activity (IC₅₀ 1.38 ± 0.19 mg/mL) compared to other enzyme treatments and the crab mince control, and its α-amylase inhibitory activity (IC₅₀ 11.02 ± 0.69 mg/mL) was lower than its α-glucosidase inhibitory activity. Its GLP-1 secretory activity was approximately four times higher than the positive control (10 mM glutamine). The <3 kD fraction contributed significantly to the anti-hyperglycemic activity of Protamex-derived hydrolysates, and this activity was stable after simulated digestion. Our results suggest that green crab hydrolysates obtained by Protamex treatment have the potential for type 2 diabetes management and could be incorporated in food products as a health-promoting ingredient.

Effects of irradiation on the structure and properties of glycosylated soybean proteins

At present, there are few reports on the glycosylation modification of soybean proteins under irradiation. In this paper, a soybean protein isolate and maltose were used as raw materials to prepare a glycosylated soybean protein under gamma-ray treatment to improve the functional properties and evaluate the changes in the structure. The results of analysis of the graft degree, browning index, polyacrylamide gel electrophoresis, infrared spectrum, fluorescence spectrum and ultraviolet spectrum of the modified product showed that the Maillard reaction between the soybean protein isolate and maltose occurred and the structure of the reaction product changed. When the irradiation dose was 7.5 kGy, the solubility of modified products increased by 23 ± 0.21% compared with that of the control group. The foaming property and foam stability increased by 62.5 ± 0.34% and 41 ± 0.47%, respectively. Emulsification, water absorption capacity and fat absorption capacity of glycosylated compounds also increased significantly. Compared with other modification methods, irradiation technology had the advantages of short action time, high efficiency and low cost, and more importantly, its industrial production was easy to implement. This experiment combined irradiation technology with the glycosylation modification method. It was proved that irradiation could promote the Maillard reaction between the soybean protein isolate and maltose, and significantly improve the functional properties of the modified protein, providing theoretical and technical support for expanding the application of the soy protein isolate in the food industry.

Effects of enzyme type and process time on hydrolysis degree, electrophoresis bands and antioxidant properties of hydrolyzed proteins derived from defatted Bunium persicum Bioss. press cake

The present study aimed at investigating the effect of enzymatic hydrolysis times (40-240 min) with alcalase and pancreatin in enzyme-substrate ratio (2% w/w) on the hydrolysis degree, electrophoresis bands, antioxidant properties and chelating activities of iron and copper ions of bioactive peptides derived from defatted Bunium persicum Bioss. (black cumin) press cake. The hydrolysis degree was enhanced by increasing the process time using both enzymes. Both hydrolysis of the enzymes were led to producing peptides with low molecular weight (less of 10 kDa). The DPPH^• radical scavenging activity was more influenced by peptides hydrolyzed by alcalase. But, the products hydrolyzed by pancreatin had a higher inhibitory effect on the ABTS^•+ cationic radical than alcalase hydrolysis. The primary protein reducing power was reached the highest level after enzymatic hydrolysis by alcalase and pancreatin, respectively, for 200 and 240 min. Following the use of proteins hydrolyzed by alcalase and pancreatin, the production of thiobarbituric acid reactive substances was also diminished from 0.45 to 0.42 and 0.38 (mg MDA/L emulsion), respectively. After assessing the iron ion chelating, a higher level of activity was observed in the alkaline-derived enzyme hydrolysis samples. Furthermore, the highest amount of copper ion chelating was obtained after hydrolyzing the enzymes for 200 min.

Release principle of peptides and amino acids during the autolysis of shrimp head from Litopenaeus vannamei after UV-C irradiation stress

UV-C irradiation can activate endogenous enzymes in the body of many aquatic animals. Autolysis kinetics of shrimp head after UV-C irradiation stress was investigated. During the first 5 hr of autolysis, the release of the autolysis products was in line with the first-order equations of the reaction rate: Y = 37.681e-0.173 t , Pe = -1.769Y + 74.156, and TP = -1.5117Y + 60.866. A good linear correlation was founded between the release of total protein and that of products with molecular weight of 3,000 Da after these products associated with residual total protein were autolyzed. In contrast to the inconsistent effect of substrate concentration on autolysis rate constants, the effects of pH and temperature on the autolysis rate constants of shrimp head showed a consistent pattern. An Arrhenius equation (lnKa = 8,090.2/T - 26.497) was established to validate the proposed autolysis kinetic equations. The autolysis rate of products with molecular weight < 3,000 Da increased rapidly from 0 hr to 3 hr. The aliphatic amino acids showed a higher amount release than that of other amino acids during the autolysis. The amounts of released heterocyclic amino acids (Trp and His) were also much more than that of other amino acids.

Effect of enzyme types on the stability of oil-in-water emulsions formed with rice protein hydrolysates

BACKGROUND

Common oil-in-water plant-based emulsions are allergenic and unstable to environmental stress, leading to increased consumer concerns about the food industry. To solve the problem of safety and instability, we investigated the influence of environmental stress on the stability of emulsions containing various rice protein hydrolysates, and compared the performance to whey protein, a common food emulsifier.

RESULTS

Rice protein hydrolysates were obtained by enzymatic hydrolysis with different proteases (neutrase, trypsin and alcalase). We evaluated the stability of emulsions produced with different hydrolysates according to storage, pH, ionic strength and thermal processing. Trypsin hydrolysates formed emulsion as stable as emulsion containing whey protein against a range of environmental stress containing pH (pH 6 to 7), salt (< 150 mmol L^-1 NaCl) and temperature (30-90 °C). Moreover, a higher partition coefficient of protein in emulsion showed that the trypsin hydrolysates were easy to adsorb at the oil-water droplet interface, indicating its higher stability.

CONCLUSION

The results obtained in the present study suggest that trypsin hydrolysates could be utilized as natural emulsifiers to stabilize emulsion instead of traditional animal-based emulsifiers, opening many opportunities with respect to hypoallergenic emulsion systems in the food industry. © 2019 Society of Chemical Industry.

Effects of Processing Conditions on the Simultaneous Extraction and Distribution of Oil and Protein from Almond Flour

The enzyme-assisted aqueous extraction process (EAEP) is an environmentally friendly strategy that simultaneously extracts oil and protein from several food matrices. The aim of this study was to investigate the effects of pH (6.5–9.5), temperature (45–55 °C), solids-to-liquid ratio (SLR) (1:12–1:8), and amount of enzyme (0.5–1.0%) on the extraction and separation of oil and protein from almond flour using a fractional factorial design. Oil and protein extraction yields from 61 to 75% and 64 to 79% were achieved, respectively. Experimental conditions resulting in higher extractability were subsequently replicated for validation of the observed effects. Oil and protein extraction yields of 75 and 72% were achieved under optimized extraction conditions (pH 9.0, 50 °C, 1:10 SLR, 0.5% (w/w) of enzyme, 60 min). Although the use of enzyme during the extraction did not lead to significant increase in extraction yields, it did impact the extracted protein functionality. The use of enzyme and alkaline pH (9.0) during the extraction resulted in the production of more soluble peptides at low pH (5.0), highlighting possible uses of the EAEP skim protein in food applications involving acidic pH. The implications of the use of enzyme during the extraction regarding the de-emulsification of the EAEP cream warrant further investigation.

Antihypertensive and antioxidant activities of enzymatic wheat bran protein hydrolysates

Bioactive peptides from plant protein sources have been continuously identified as nutrient supplements for low toxicity but multiple physiological activities such as antihypertensive, antioxidant, and anti-inflammatory. In this study, wheat bran protein isolate was digested with alcalase to produce wheat bran protein hydrolysate (WPH) that was then separated into different peptide fractions (<1, 1-3, 3-5, and 5-10 kDa) by membrane ultrafiltration. WPH and the peptide fractions were evaluated for in vitro activities such as antioxidant, renin inhibition, and angiotensin-converting enzyme (ACE) inhibition. In addition, the blood pressure-lowering effects of WPH and the <1 kDa peptides were determined by oral administration to spontaneously hypertensive rats (SHRs). Results showed that the ACE and renin inhibitions were significantly (p < .05) higher for the <1 kDa fraction (84.25% ± 2.45%, 75.19% ± 1.75%, respectively) when compared to the WPH and >1 kDa fractions. The <1 kDa fraction also showed significantly (p < .05) higher oxygen radical antioxidant activity with 2044.73 ± 37.45 (μM TE/g protein) when compared to lower values obtained for the >1 kDa membrane fractions and WPH. Oral administration (100 mg/kg body weight) of the <1 kDa membrane fraction to SHRs resulted in a better decrease (-35 mmHg) in the systolic blood pressure when compared to the WPH (-20 mmHg) after 6 hr. And seven peptides (NL, QL, FL, HAL, AAVL, AKTVF, and TPLTR) were identified and amino acid sequence was determined by tandem mass spectrometry. We conclude that the WPH could be considered as a suitable natural antihypertensive and antioxidant resource. PRACTICAL APPLICATIONS: The results of the present study indicate that WPH and its ultrafiltration fractions possess potential as a source of antihypertensive and strong antioxidant peptides. It has been proved that wheat bran has a good blood pressure lowering and antioxidation and other biological activities, and the <1 kDa fraction showing high oxygen radical absorbance capacity level also has better in vitro ACE inhibition and renin-inhibitory activity. The higher antihypertensive efficiency of the <1 kDa fraction may be because the peptides can be better absorbed from the gastrointestinal tract or an increased ability to interact with the enzyme (ACE or renin) protein structure to change the active conformation and lead to decreased catalysis. The results of this study indicate that WPH, especially <1 kDa peptide, can be used as a component in formulating antihypertensive functional foods and nutraceuticals, thus improving the industrial production efficiency and bioavailability of wheat bran.

The effect of pH on the stabilization and digestive characteristics of soybean lipophilic protein oil-in-water emulsions with hypromellose

The development of functional foods requires a detailed understanding of the behavior of lipophilic protein (LP) in the presence of emulsion stabilizers at different pH conditions. In this study, we examined the interaction between hydroxypropyl methylcellulose (hypromellose, HPMC) and soybean lipophilic protein. To that end, we examined the stabilities of LP-HPMC emulsions at pH 3, 5, and 7, as well as the oil-release behavior of LP-HPMC emulsions during digestion. Fluorescence data showed that HPMC binds to LP with quenching at a single binding site that did not change with pH. Atomic-force microscopy, emulsification, and oxidation-stability analyses showed that HPMC improves the pH stability of the LP-HPMC emulsions, while simulated in-vitro digestion experiments showed that added HPMC delayed the release of lipids to varying degrees. The results of this study will aid in the development of emulsion-based functional foods, pharmaceutical carriers with controlled-release or sustained-release functional ingredients.

The purification and identification of immunoregulatory peptides from oyster (Crassostrea hongkongensis) enzymatic hydrolysate

Oysters, favored as a delicious seafood by people worldwide, contain various nutritional components, especially proteins. In this work, the immunoregulatory peptides were isolated and purified from oyster enzymatic hydrolysate by utilizing anion exchange chromatography and RP-HPLC, and were identified via LC-MS/MS. A proliferation assay, a phagocytosis assay, and TNF-α production, NO production and IL-6 production assays were used to examine the immunoregulatory effects of the two identified peptides. The results indicate that the peptides, DNSIAMESMK (P1) and LLQLGSGR (P2), increased the proliferation rate of macrophages, TNF-α and NO production, IL-6 production, and the phagocytosis ability, but to different degrees; P2, with more hydrophobic amino acids, was more potent than P1. This suggested that these peptides might be potential candidates for developing immunoregulatory functional foods and nutraceuticals.

Changes in ACE inhibitory and antioxidant activities in alcalase treated idli batter and idli after fermentation

Idli is a cereal-legume fermented food consumed widely in India. Fermentation and addition of external enzymes have been suggested as methods for release of bioactive peptides from parent proteins. The present study was aimed at exploring the changes in angiotensin-I converting enzyme (ACE) inhibitory and antioxidant activity of 14 h fermented idli batter treated with alcalase in varied amounts (100-700 U/g batter) kept at 30 ± 2 °C. Various batter parameters along with sensory attributes of cooked idli were assessed. The viscosity (12170-7795 cP) and rise in volume (29-20 mL) of batter decreased with addition of alcalase in the batter when compared with control batter (14130 cP, 31 mL). The free amino nitrogen content and radical scavenging activity of alcalase treated batter exhibited an increase by 2-5 and 2-7 fold, respectively while ACE inhibitory activity showed a decrease in IC₅₀ value (lowest being 52.53 ± 1.12 mg/mL of batter containing 600 U alcalase/g batter) when compared with the control fermented set. The hardness and bulk density values of control cooked idli was 0.59 kg and 0.53 g/cm³, respectively while alcalase treated idlis showed a range of 0.71-1.68 kg and 0.53-0.69 g/cm³. The overall acceptance of idli prepared from alcalase treated batters till 600 U/g batter was judged as 'good' by semi-trained panellists. Moreover, the ACE inhibitory and radical scavenging activity of cooked idli prepared from 600 U alcalase/g batter showed enhancement over the control idli. Thus, alcalase treated idli shows potential to be used as a functional food.

Revealing Antioxidant and Antidiabetic Potency of Melinjo (Gnetum Gnemon) Seed Protein Hydrolysate at Different Stages of Seed Maturation

roteins hydrolyzed from melinjo seeds (Gnetum gnemon) at green (GM), yellow (YM) and red (RM) stages of maturity were studied for their effectiveness in antioxidant and antidiabetic activities. The seed protein extract was hydrolyzed using alcalase 2.4L, and the resulting hydrolysates with the highest degree of hydrolysis, protein profile, and the most potent contributors to antioxidant and invitro antidiabetic activities were identified. The degree of hydrolysis value of hydrolysates ranged from 52-84%, and the SDS-PAGE protein profile showed two distinct bands in which the band with molecular weight of 30 kDa degraded more intensively. Antioxidant capacity was measured using different standard methods, including radical cation 2,2-azinobis-(3-ethylbenzothizoline-6-sulphonate) (ABTS•+) assay, hydroxyl radical (OH•), and superoxide anion (O2•-) scavenging. The green hydrolysate (GMH) had significantly higher (p<0.05) free radical scavenging (ABTS•+, OH•, and O2•-) activities than that of the yellow hydrolysate (YMH) and red hydrolysate (RMH). However, invitro antidiabetic testing was performed based on the inhibitory activity of α-amylase and α-glucosidase. GMH was found to be more effective than YMH and RMH. These results showed that the antioxidant and antidiabetic activity in hydrolyzed GM protein has high potential to be utilized as natural nutraceuticals.

Aqueous and Enzymatic Extraction of Oil and Protein from Almond Cake: A Comparative Study

The almond cake is a protein- and oil-rich by-product of the mechanical expression of almond oil that has the potential to be used as a source of valuable proteins and lipids for food applications. The objectives of this study were to evaluate the individual and combined effects of solids-to-liquid ratio (SLR), reaction time, and enzyme use on oil and protein extraction yields from almond cake. A central composite rotatable design was employed to maximize the overall extractability and distribution of extracted components among the fractions generated by the aqueous (AEP) and enzyme-assisted aqueous extraction process (EAEP). Simultaneous extraction of oil and protein by the AEP was favored by the use of low SLR (1:12.82) and longer reaction times (2 h), where extraction yields of 48.2% and 70% were achieved, respectively. Increased use of enzyme (0.85%) in the EAEP resulted in higher oil (50%) and protein (75%) extraction yields in a shorter reaction time (1 h), compared with the AEP at the same reaction time (41.6% oil and 70% protein extraction). Overall, extraction conditions that favored oil and protein extraction also favored oil yield in the cream and protein yield in the skim. However, increased oil yield in the skim was observed at conditions where higher oil extraction was achieved. In addition to improving oil and protein extractability, the use of enzyme during the extraction resulted in the production of skim fractions with smaller and more soluble peptides at low pH (5.0), highlighting possible uses of the EAEP skim in food applications involving acidic pH. The implications of the use of enzyme during the extraction regarding the de-emulsification of the EAEP cream warrant further investigation.

Effects of heating or ultrasound treatment on the enzymolysis and the structure characterization of hempseed protein isolates

The effects of heating (90 °C/30 min) or ultrasound (200/400/600 W) treatment on antioxidant and angiotensin-converting enzyme inhibitory (ACEI) activity of hydrolysates from hempseed protein isolates (HPI) were studied. The secondary structure, surface hydrophobicity, intrinsic fluorescence, scanning electron microscopy (SEM) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of HPI treated by heating or ultrasound were measured. The results showed that hydrolysate from HPI treated with ultrasound at 200 W showed higher hydrolysis degree, proportion of lower molecular mass components (1.0-3.0 kDa), antioxidant and ACEI activity than those from heating or high-power treated. The changes in secondary structure, surface hydrophobicity and intrinsic fluorescence indicated the unfolding of HPI after ultrasound. The SEM results showed that HPI treated with ultrasound at 200 W exhibited decrease in particle size and deformation and further increased in power caused the aggregates of HPI. In conclusion, the ultrasound treatment at low-power was superior to 90 °C/30 min treatment in facilitating enzymatic release of antioxidant and ACEI peptides from HPI.

Changes to the tropomyosin structure alter the angiotensin-converting enzyme inhibitory activity and texture profiles of eel balls under high hydrostatic pressure

Changes in the structure of tropomyosin (TM) altered the texture profiles of eel balls and the inhibitory activity of the angiotensin-converting enzyme (ACE). The secondary and tertiary structure of TM was determined after high hydrostatic pressure (HHP) treatment. The correlation between the spatial structure of TM and the texture profiles of eel balls was developed and discussed. The β-sheet was converted to a β-turn and a random coil when treated at HHP (200-400 MPa), meanwhile the α-helix unfolded and was converted into a β-sheet, β-turn and a random coil with treatment at 500 and 600 MPa. The surface hydrophobicity (H0) was increased and the sulfhydryl (SH) content decreased with an increase in the pressure. The results indicated that the texture profiles of eel balls showed a negative relationship with the α-helix, β-sheet and SH content. The texture profiles of eel balls were greatly enhanced after treatment at 500 and 600 MPa, leading to the improved surface network of the eel ball products. The ACE inhibitory activity of TM after HHP treatment exhibited a positive relationship with the β-sheet content in the protein. The ACE inhibitory activity was preserved under 600 MPa.

Influence of spray drying encapsulation on the retention of antioxidant properties and microstructure of flaxseed protein hydrolysates

In this research, bioactive peptides produced from flaxseed protein by alcalase, pancreatin, trypsin and pepsin, were encapsulated by spray drying. After analysis of amino acid composition and antioxidant properties of hydrolysates, the effect of spray-drying encapsulation via different maltodextrin (MD) to hydrolysate ratios (1:1, 2:1 and 3:1 w/w) on the production yield, physicochemical properties, functional activities, chemical structure, and morphology of final powder particles were evaluated. Among the hydrolysates, peptides produced with alcalase had the highest hydrolysis degree (38.2%), hydrophobic amino acids (255 mg/g) and antioxidants (126 mg/g). Among spray-dried samples, the powders obtained by 3:1 w/w ratio (MD: peptide) showed the highest radical scavenging activity for DPPH^- (68.93%), ABTS⁺ (85.62%), hydroxyl (94.97%), nitric oxide (64.03%), reducing power (95.49%), total antioxidant activity (96.68%), and iron (95.31%) and copper (95.49%) chelating activity. Evaluation of chemical structure (FTIR) indicated that hydrolysates were coated and dispersed within maltodextrin matrix. SEM images showed the effect of different carrier ratios on the production of irregular and shrunk particles with different sizes and matrix-type structures.

Antioxidant properties and instrumental quality characteristics of spray dried Pangasius visceral protein hydrolysate prepared by chemical and enzymatic methods

Fish protein hydrolysates are digested form of protein with various bioactive properties where, the cleavages of molecular bonds of proteins can be broken by the enzymatic and chemical process. In this study, antioxidant properties of spray dried protein hydrolysate prepared from Pangasius viscera by using enzymatic (papain and pepsin), and chemical methods (hydrochloric acid and sodium hydroxide) were evaluated. Among the different treatments, pepsin-derived visceral protein hydrolysate showed the maximum antioxidant activity when used at higher concentrations. Essential amino acids (EAA) and hydrophobic amino acids are higher in papain-derived visceral protein hydrolysate. In pepsin-derived visceral protein hydrolysate, major proportion was contributed by glycine (Gly), glutamine (Glu), proline (Pro), and asparagine (Asp). Higher amount of aromatic amino acids are found in alkali-derived FVPH. Scanning electron microscopy (SEM) images of pepsin fish visceral protein hydrolysate showed better globular structure than the other treatments. It can be concluded that among the different treatments, the visceral protein hydrolysate prepared with pepsin had better overall quality regarding antioxidant properties and papain in nutritional point of view.