Content Of Hydrophobic Amino Acids Research Articles

Comparison of Alternative Protein Hydrogels for Delivering Myricetin: Interaction Mechanism and Stability Evaluation.

Food protein carriers from different sources might have distinct stabilizing and enhancing effects on the same small molecule. To elucidate the molecular mechanism, five different sourced proteins including soy protein isolates (SPIs), whey protein isolates (WPIs), edible dock protein (EDP), Tenebrio molitor protein (TMP), and yeast protein (YP) were used to prepare protein hydrogels for delivering myricetin (Myr). The results suggested that the loading capacity order of Myr in different protein hydrogels was EDP (11.5%) > WPI (9.3%) > TMP (8.9%) > YP (8.0%) > SPI (7.6%), which was consistent with the sequence of binding affinity between Myr and different proteins. Among five protein hydrogels, EDP had an optimum loading ability since it possessed the highest hydrophobic amino acid content (45.52%) and thus provided a broad hydrophobic cavity for loading Myr. In addition, these protein-Myr composite hydrogels displayed the core-shell structure, wherein hydrogen bonding and hydrophobic interaction were the primary binding forces between proteins and Myr. Moreover, the thermal stability, storage stability, and sustained-release properties of Myr were significantly enhanced via these protein delivery systems. These findings can provide scientific guidance for deeper utilization of food alternative protein sources.

Effect of limited hydrolysis with endopeptidase on bitterness properties of wheat gluten hydrolysates

The application of limited hydrolysis on wheat gluten (WG) has been found to be a highly effective method for improving a wide range of functional properties associated with plant protein. However, the bitter peptides formed during this process have an unpleasant bitterness. To provide a theoretical framework for de-bittering techniques, this study examined the modulation of bitterness intensity in wheat gluten hydrolysates (WGHs) by manipulating enzyme cleavage sites and degree of hydrolysis (DH). It was found that the bitter peptide's release content increased significantly, and the bitterness threshold decreased markedly with increasing DH. Furthermore, the structure-bitterness threshold association of bitter peptides was investigated. The results indicated that peptide segments in molecular weights (MW) from 500 to 1000 exhibited the greatest influence on bitterness threshold compared to peptides with other MWs. The percentage of total hydrophobic amino acid content and position of some hydrophobic amino acids in the amino acid sequence had a significant effect on the bitterness threshold. Finally, 47 peptides were identified by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis. These peptides were mainly small peptides with less than 13 amino acid residues and MW below 1500 Da, and most of them had Q values higher than 5855 J/mol.

Cowhide gelatin peptide as a source of antioxidants for inhibiting the deterioration of pudding quality during storage

To investigate the effect of gelatin peptide on the inhibition of quality deterioration in stored pudding, gelatin peptide with antioxidant properties was added to pudding products. For this purpose, a pudding recipe containing gelatin peptides was created. The gelatin peptides were characterized based on their antioxidant activity and protein structure. It was found that gelatin peptides had better antioxidant properties, lower thermal stability and crystallinity, higher hydrophobic amino acid content, and greater surface hydrogen bond exposure than commercially available peptides. Properties such as the pH, colony growth, and sensory characteristics of the pudding were characterized at 4 °C and 25 °C. The results showed that the addition of 0.5–1.0 % gelatin peptide to pudding was capable of significantly (P< 0.05) slowing down the decline in pH and sensory scores of the pudding and significantly inhibiting colony growth. It could prolong its storage life by five days at 4 °C and three days at 25 °C.

Antioxidant and angiotensin converting enzyme inhibitory activities of red lionfish (Pterois volitans L.) muscle protein hydrolysates obtained using pepsin-pancreatin system

Despite being an invasive species and representing a threat in the area, red lionfish (Pterois volitans L.) meat is valued for its pleasant taste and high protein content. The objective of the present work was to evaluate the angiotensin converting enzyme inhibition (ACE-I) and the antioxidant activities of red lionfish muscle protein hydrolysates in vitro. Hydrolysates were obtained using the pepsin-pancreatin system, and their degree of hydrolysis (DH), electrophoretic, and amino acid profile were determined. Subsequently, their ACE-I and ABTS+ radical scavenging activity were evaluated, selecting those with the highest response. The highest DH (66.1%) was found in the hydrolysate obtained at 120 min of reaction time (H120); electrophoresis revealed the action of the enzymes on the muscle proteins. The highest bioactivities occurred during hydrolysis with pepsin for 60 min (H60), obtaining the highest ACE-I of 68.8% (evaluated with 500 µg protein) with a DH of 16.8%, ACE-I related amino acid content of 33.6%, and hydrophobic amino acid content of 42.9%. With the 30 min hydrolysates (H30), the highest Trolox equivalent antioxidant capacity of 60.3 mM/mg protein was obtained with 18.4% DH and 22.1% radical scavenger amino acids; its comparison with H120 proved that higher DH did not produce a greater response in ABTS+ radical scavenging activity, DPPH, reducing power, and copper chelation assays; with β-carotene bleaching being the exception. Therefore, it can be concluded that red lionfish muscle hydrolysates could be a promising source of peptides with antihypertensive and antioxidant properties, and can be suitable as functional ingredients.

Nano casein-pectin complex: exploring physicochemical, organoleptic properties, and LAB viability in skimmed milk and low-fat yoghurt.

Protein complexes with a nutritional value, heat stability, and gelling properties with no negative impact on culture viability have promising application prospects in the fermentation industry. The aim of the study was to investigate the possibility of applying physical modification seeking high-protein-fortified yoghurt production using the nano casein-pectin NCP complex as an active colloidal system with enhanced structural and thermal properties and monitor the quality properties of the physicochemical, heat stability, rheological, starter culture viability and sensory evaluation of fortified products comparing with the plain control throughout the cold storage. High-energy ball milling (HEBM) technique was used to produce nanoparticles of casein powder and smaller particles of pectin individually, and particle size and zeta potential was assessed. Deferent Nano casein-pectin (NCP) complex formulations were prepared, their physicochemical properties were assessed including protein quality via Amino Acid Analyzer (AAA), viscosity, thermogravimetric analysis (TGA), and then used in fortification of skimmed milk and low-fat yoghurt to monitor the fortification effects. The particle sizes showed to be ≈166 nm and 602.6 nm for nano-casein and pectin, respectively. Milk fortification with the NCP complex has significantly increased the nutritional value represented in increased protein content (7.19 g/100 g in NCP5); Ca, P, and S content (2,193.11, 481.21, and 313.77 ppm); and amino acid content with first limiting amino acids; histidine (0.89 mg/g), methionine (0.89 mg/g), and low content of hydrophobic amino acids (HAAs) may cause aggregation. NPC fortification enhanced physicochemical properties announced in enhanced viscosity (62. mP.s in NCP5) and heat stability (up to 200°C) compared with control skimmed milk (SM). NCP yoghurt fortification significantly increased protein content to 11 mg/100 g in T5, enhanced viscosity to 48.44 mP.s in T3, decreased syneresis to 16% in T5, and enhanced LAB viability which was translated in preferable sensorial properties. Applying fortification with nanoparticles of the casein-pectin (NCP) complex balanced the amino acid content and improved physicochemical, rheological, nutritional, and sensorial properties and LAB viability, which can be recommended further in functional food applications.

High pressure-assisted enzymatic hydrolysis promotes the release of a bi-functional peptide from cowhide gelatin with dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant activities

The process of generating functional peptides from cowhide gelatin is challenged by inefficient enzymatic hydrolysis. In this study, the researchers attempted to enhance the hydrolysis and potential functional properties of the peptides by subjecting the cowhide gelatin to high-pressure treatment (200, 300, and 400 MPa) for 20 min, followed by enzymatic hydrolysis. The highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2′ azinobis(3 ethylbenzothiazoline 6 sulfonic acid) (ABTS) radical scavenging activity, and DPP-IV inhibitory activity of the hydrolysate were obtained at 200 MPa, accompanied with an increase in the content of hydrophobic, acidic, and basic amino acids (P < 0.05). Correspondingly, the high-pressure pretreatment (200 MPa) reduced the thermal stability, particle size, and morphological integrity of cowhide gelatin, with a corresponding increase in the exposure of hydrophobic regions. Altogether, these results indicated that appropriate high-pressure-assisted enzymatic hydrolysis reinforced the release of bi-functional peptides by modifying the structure of cowhide gelatin.

The antifreeze activity and physicochemical properties of Litopenaeus vannamei head autolysate

SummaryLitopenaeus vannamei heads were autolysed at a constant temperature of 50 °C, pH 7.0 for a maximum duration of 5 h, and the antifreeze activity and physicochemical properties of the head autolysates were determined. Thermal hysteresis (TH) was used as an index for determining the antifreeze activity of the shrimp head autolysates. The highest thermal hysteresis activity was 1.82 °C which was measured in the 5 h‐shrimp head autolysate. The highest negative zeta potential value (−41.06 ± 2.08 mV) and surface hydrophobicity (295.575 ± 9.7819) were in the 5 and 1.5 h autolysate groups, respectively. Generally, &lt;2000 Da components accounted for over 85% of the total molecular weight in all shrimp head autolysate groups. Pearson correlation analysis was used to investigate how physicochemical properties influenced the thermal hysteresis index. Although at varying degrees, the analysis confirmed that a positive correlation existed between TH activity and molecular weight, hydrophobic amino acid content, and surface hydrophobicity. A negative correlation existed between TH activity and zeta potential, and hydrophilic amino acids. The findings of our study suggest that Litopenaeus vannamei head autolysate has a potential antifreeze effect and that the physicochemical properties influence its thermal hysteresis.

Nitrogen regulates the synthesis of hydrophobic amino acids to improve protein structural and gel properties in common buckwheat

Nitrogen (N) fertilizer impacts the grain quality of common buckwheat, but the effects and regulatory mechanisms of N on various protein parameters of buckwheat are not fully understood. The purpose of this study was to investigate the particle morphology, structural and gel properties, and regulation mechanism of buckwheat protein under four N levels. The bulk density, surface hydrophobicity, particle size, and thermal properties of the buckwheat protein were maximized through the optimal N application (180 kg N/ha), further enhancing the thermal stability of the protein. N application increased the β-sheet content and reduced the random coil content. Appropriate N fertilizer input enhanced the tertiary structure stability and gel elasticity of buckwheat protein by promoting hydrophobic interactions, disulfide bonds, ionic bonds, storage modulus and loss modulus. The differentially expressed proteins induced by N are primarily enriched in small ribosomal subunit and ribosome, improving protein quality mainly by promoting the synthesis of hydrophobic amino acids. Future agriculture should pay attention to the hydrophobic amino acid content of buckwheat to effectively improve protein quality. This study further advances the application of buckwheat protein in the field of food processing and provides a theoretical basis for the extensive development and utilization of buckwheat protein.

Modification of sunnhemp (Crotalaria juncea) protein isolate by high intensity ultrasound: Impact on the molecular structure, amino acid composition and nutritional profiling

In the present study, sunnhemp protein isolate (SHPI) was prepared by alkaline extraction followed by acid precipitation method. The prepared sunnhemp protein isolate was subjected to high-intensity ultrasound treatment at 40 and 50% ultrasound amplitude for 10, 20, and 30 min. The effect of ultrasound treatment on molecular flexibility, available lysine content, antioxidant properties, and molecular weight distribution was investigated. The antioxidant activity of ultrasound treated SHPIs was found to be higher than the untreated sample. The optimum ultrasound treatment condition (50% amplitude and 20 min) had the highest molecular flexibility and antioxidant properties among all the sunnhemp protein isolates. The available lysine content of all SHPI samples decreased after ultrasound treatment. SDS-PAGE results demonstrated that there was no change in the electrophoresis patterns of ultrasound treated SHPI samples over the untreated sample, thus indicating the primary structure of the sunnhemp protein isolate was intact. Hydrophobic amino acid content was improved after ultrasound treatment in US5 (50% amplitude for 20 min) sample, thereby resulting in increase in total amino acid content than SHPI without ultrasound treatment. Biological value and essential amino acid index were also improved due to ultrasound treatment in US5 sample. Leucine and isoleucine were the first and second limiting amino acids found in SHPI according to FAO/WHO scoring patterns. Overall, it can be concluded that ultrasound treated SHPI can be a valuable source of plant-based protein with desirable nutritional characteristics at a low cost. The current findings speculated that high-intensity ultrasound treatment can be a valuable technique for the modification of sunnhemp protein isolate with its promising utilization in food supplements.

The Nutritional and Functional Properties of Protein Isolates from Defatted Chia Flour Using Different Extraction pH.

This study aims to determine the effects of various alkaline pHs on the nutritional and functional properties of protein isolated from defatted chia flour (DCF). The DCF isolated using alkali extraction method at pH 8.5, 10.0, and 12.0 were coded as CPI-8.5, CPI-10.0, and CPI-12.0, respectively. The highest extraction yield and protein recovery yield was demonstrated by CPI-12.0 (19.10 and 59.63%, respectively), with a total protein content of 74.53%, and glutelin showed the highest portion (79.95%). The CPI-12.0 also demonstrated the most elevated essential (36.87%), hydrophobic (33.81%), and aromatic (15.54%) amino acid content among other samples. The DCF exhibited the highest water (23.90 gg-1) and oil (8.23 gg-1) absorption capacity, whereas the CPI-8.5 showed the highest protein solubility (72.31%) at pH 11. DCF demonstrated the highest emulsifying capacity at pH 11 (82.13%), but the highest stability was shown at pH 5 (82.05%). Furthermore, CPI-12.0 at pH 11 shows the highest foaming capacity (83.16%) and stability (83.10%). Despite that, the CPI-10.0 manifested the highest antioxidant capacity (DPPH: 42.48%; ABTS: 66.23%; FRAP: 0.19), as well as ACE-I (35.67%). Overall, the extraction pH had significant effects in producing chia protein isolates (CPI) with improved nutritional and functional qualities.

Ultrasonic-aided extraction and degossypolization of cottonseed meal protein: Optimization and characterization of functional traits and molecular structure

Cottonseed meal (CM) is a useful protein resource, but the presence of gossypol (a toxic compound) limits it utilization in industry. To reduce the gossypol content, the use of ultrasonication in extracting protein from CM was explored. Following single-factor experiments, operative limits of independent variables affecting removal ratio of total-gossypol (RRTG) and extractability of CM protein (CMP) were achieved as temperature (35–55 °C), sonication power (250–350 W), time (12–24 min), and NaOH concentration (2–6 g/L). Box-Behnken’s Design centered on a 3–level-4–factor was employed to optimize ultrasonication conditions on the yield and RRTG of CMP. The predictive models were statistically adequate (p < 0.0001) to reflect the experimental results of the responses as verified by insignificant lack-of-fit (p ≥ 0.1333) and high coefficient of determination (R2 ≥ 0.976) values. The optimized sonication conditions for two responses were 53 °C, 320 W, 21 min, and 4.6 g-NaOH/L. Under optimized conditions, the observed removal ratio of free- and total-gossypol and yield values were 93.21 %, 87.56 %, and 58.23 %, which substantially increased by 15.64 %, 12.88 %, and 29.56 %, respectively over control (alkaline extraction). Furthermore, sonicated isolate showed an increase in solubility and emulsion property relative to control, buttressed by particle sizing and zeta potential outcomes. Sodium dodecyl sulfide polyacrylamide gel electrophoresis (SDS-PAGE), Fourier Transform Infrared (FTIR) spectroscopy, atomic force microscopy (AFM), and amino acid data showed notable changes in molecular weight, functional groups, surface topography, and hydrophobic amino acid content of CMP, respectively (i.e., after sonication), suggesting partial unfolding in CMP conformation. Accordingly, CMP isolates (especially the sonicated protein) could be considered edible because of the observed low gossypol content (< 0.045 %) and thus can be utilized as natural additives in food formulations.

Effects of ultrasonic treatment on the structural and functional properties of cactus (Opuntia ficus-indica) seed protein

With the steady increase in the consumption of ultra-processed foods, there is growing interest in sustainable diets that include more plant protein. However, little information is available regarding the structural and functional properties of cactus (Opuntia ficus-indica) seed protein (CSP), a by-product of the cactus seed food-processing chain. This study aimed to explore the composition and nutritional value of CSP and reveal the effects of ultrasound treatment on protein quality. Protein chemical structure analysis showed that an appropriate intensity of ultrasound treatment (450 W) could significantly increase protein solubility (96.46 ± 2.07%) and surface hydrophobicity (13.76 ± 0.85 μg), decrease the content of T-SH (50.25 ± 0.79 μmol/g) and free-SH (8.60 ± 0.30 μmol/g), and enhance emulsification characteristics. Circular dichroism analysis further confirmed that the ultrasonic treatment increased the α-helix and random coil content. Amino acid analysis also suggested that ultrasound treatment (450 W) increased the hydrophobic amino acid content. To evaluate the impact of changes in the chemical structure, its digestion behavior was studied. The results showed that ultrasound treatment increased the release rate of free amino acids. Furthermore, nutritional analysis showed that the digestive products of CSP by ultrasound treatment can significantly enhance the intestinal permeability, increase the expression of ZO-1, Occludin and Claudin-1, thus repairing LPS induced intestinal barrier disfunction. Hence, CSP is a functional protein with high value, and ultrasound treatment is recommended. These findings provide new insights into the comprehensive utilization of cactus fruits.

Difference analysis of the structure and functional properties among coix seed prolamin fractions (α-, β-, and γ-coixin).

The differences in proteins in structural characteristics are reported to affect their physicochemical and functional properties. In this study, three types of prolamins (γ-, α-, and β-coixin) derived from coix seed separately distributed among fractions 1-3 extracts. They were studied respecting molecular weight, amino acid composition, secondary structure, microstructure, surface hydrophobicity, solubility, water holding capacity, and oil holding capacity. Results showed that the molecular weights of those three fractions were between 10 and 40kDa. The secondary structure of those fractions was almost the same, mainly based on β-sheet and irregular structure. The microstructure of α- and γ-coixin presented an irregular shape, whereas β-coixin presented a regular spherical shape. Those three fractions exhibited species of abundant essential amino acids with the same amino acid composition but different contents. The β-coixin fraction had the highest content of hydrophobic amino acids (238.39mg/g) followed by the α-coixin fraction (235.05mg/g), whereas the γ-coixin fraction had the lowest content (33.27mg/g). The γ-coixin fraction has the maximum surface hydrophobicity, whereas the β-coixin fraction has the highest solubility. In addition, the good amphiphilicity of β-coixin fraction made it possible to be used as a surfactant. The excellent functional properties of the β-coixin fraction presented in this research would widen the applications of coix seed prolamins. PRACTICAL APPLICATION: The molecular weights of those three fractions were between 10 and 40kDa. The secondary structure was almost the same, mainly based on β-sheet and irregular structure. Those three fractions exhibited species of abundant essential amino acids with the same amino acid composition but different contents. The WHC and OHC of β-coixin were the best, indicating its potential as a surfactant and forming stable lotion.

Proteolysis of burley tobacco-leaf extracts and antioxidant activity of the hydrolysates

Burley tobacco-leaf protein extracted by alkali and precipitated by acid was hydrolyzed enzymatically, and optimum protease and hydrolysis parameters were determined. Pepsin was best and gave the highest hydrolysis rate (15.55%). As per results of the single-factor test, optimum hydrolysis conditions were: temperature 37 °C, pH 2, and an [E]/[S] ratio of 5%. These hydrolysis conditions were optimized by an orthogonal experiment that rendered the same results as the single factor experiment. The ratio of essential to total amino acids and that of essential to non-essential amino acids contained in the burley tobacco-leaf protease hydrolysate were higher than the FAO/WHO standard values of 0.4 and 0.6, among which hydrophobic amino acid content was the highest, followed by negatively and positively charged amino acid contents. In vitro antioxidant experiments showed that the scavenging rates of DPPH, superoxide anion, and hydroxyl radicals of tobacco-leaf protein hydrolysates were higher than those before hydrolysis. Further, the hydroxyl radical-scavenging rate was the most significant, and total antioxidant capacity was improved. The nutritive value of the burley tobacco-leaf protein hydrolysate improved upon pepsin-mediated hydrolysis, and the antioxidant activity was better. These results provide a theoretical basis for further development and utilization of tobacco protein resources.

Structural and Physicochemical Characterization of Extracted Proteins Fractions from Chickpea (Cicer arietinum L.) as a Potential Food Ingredient to Replace Ovalbumin in Foams and Emulsions.

Chickpeas are the third most abundant legume crop worldwide, having a high protein content (14.9-24.6%) with interesting technological properties, thus representing a sustainable alternative to animal proteins. In this study, the surface and structural properties of total (TE) and sequential (ALB, GLO, and GLU) protein fractions isolated from defatted chickpea flour were evaluated and compared with an animal protein, ovalbumin (OVO). Differences in their physicochemical properties were evidenced when comparing TE with ALB, GLO, and GLU fractions. In addition, using a simple and low-cost extraction method it was obtained a high protein yield (82 ± 4%) with a significant content of essential and hydrophobic amino acids. Chickpea proteins presented improved interfacial and surface behavior compared to OVO, where GLO showed the most significant effects, correlated with its secondary structure and associated with its flexibility and higher surface hydrophobicity. Therefore, chickpea proteins have improved surface properties compared to OVO, evidencing their potential use as foam and/or emulsion stabilizers in food formulations for the replacement of animal proteins.

Exploring the Amino-Acid Composition, Secondary Structure, and Physicochemical and Functional Properties of Chickpea Protein Isolates.

This study examined the amino-acid profile, secondary structure, and physicochemical and functional properties of proteins isolated from Anatolian chickpea landraces. Secondary objective of the study was to determine whether a relationship exists between the amino-acid composition and physicochemical and functional properties. Aspartic acid and glutamic acid were the dominant amino acids, while the isolates were deficient in methionine. Secondary structures were determined by Fourier transform infrared spectroscopy, where the β-sheet was shown to be dominant. The denaturation temperature of the isolates was between 87 and 145 °C, and the highest net surface charge (≃28.6 mV) and solubility (∼95.0%) were observed at pH 9.0-10.0. The isolates' water-holding capacity varied between 2.1 and 2.7 g water/g protein, whereas their oil-holding capacity ranged between 3.4 and 4.4 g oil/g protein. Emulsion capacity, emulsifying activity, and the stability indices of isolates were found to be between 401.2 and 469.1 g oil/g protein, 14.5 and 25.7 m2/g, and 45.7 and 146.9 min, respectively. Isolates of Hisar and Erzincan chickpeas exhibited good emulsifying properties. The Yasa isolate had a relatively high hydrophobic amino-acid content and delivered the best gelation performance. Overall, significant differences in the characteristics of proteins were observed among the different chickpea landraces studied.

The Structural and Functional Differences between Three Species of Fish Scale Gelatin and Pigskin Gelatin.

In this paper, gelatin was extracted from the scales of Coregonus peled, Carp and Bighead carp by the acid method, and the structure and functional properties of the obtained scale gelatin and food-grade pigskin gelatin (FG) were compared. The results showed that all gelatins exhibited relatively high protein (86.81-93.61%), and low lipid (0.13-0.39%) and ash (0.37-1.99%) contents. FG had the highest gel strength, probably because of its high proline content (11.96%) and high average molecular weight distribution. Low β-antiparallel was beneficial to the stability of emulsion, which led FG to have the best emulsifying property. The high content of hydrophobic amino acids may be one of the reasons for the superior foaming property of Bighead carp scales gelatin (BCG). The gel strength of Carp scales gelatin (CG) and BCG, the ESI of Coregonus peled scales gelatin (CPG) and the foaming property of BCG indicate that fish gelatin has the potential to be used in food industry as a substitute for pig skin gelatin.

Taurine, homotaurine, GABA and hydrophobic amino acids content influences “in vitro” antioxidant and SIRT1 modulation activities of enzymatic protein hydrolysates from algae

Prevention and control of diseases and delaying the signs of ageing are nowadays one of the major goals of biomedicine. Sirtuins, a family of NAD+ dependent deacylase enzymes, could be pivotal targets of novel preventive and therapeutic strategies to achieve such aims. SIRT1 activating and inhibiting compounds, such as polyphenols and bioactive peptides, have been proposed to be involved in the development of many human diseases. The objective of this work was to assess and compare the antioxidant and SIRT1 modulation activities of enzymatic protein hydrolysates (EPHs) from a wide number of algae species (24 commercial samples and 12 samples harvested off the Atlantic coast of northern Spain). High antioxidant activities were observed in EPHs from red and green seaweed species. Moreover, 19 samples exhibited SIRT1 activation, while EPHs from the 16 samples were SIRT1 inhibitors. Pearson's correlation test and Principal Component Analysis revealed significant correlations between (1) total peptide and hydrophobic amino acid content in EPHs and their antioxidant activities, and (2) concentrations of taurine, homotaurine, and amino acid gamma aminobutyric acid in EPHs and their SIRT1 modulation activity.

Purification and Identification of Lipid-Lowering Protein from Barley Extract after Lactiplantibacillus plantarum dy-1 fermentation

Previous studies have found that the protein in barley extract fermented by Lactiplantibacillus plantarum dy-1 has the ability to inhibit lipid accumulation. However, the isolation, purification, and structural identification of the protein with lipid-lowering activity were still needed. In the present study, barley protein fermented by L. plantarum dy-1 with the optimal lipid-lowering ability was isolated and purified in three steps: using ammonium sulfate precipitation, anion-exchange chromatography, and size-exclusion chromatography. Combined with the model of HepG2 cells induced by oleic acid, the results showed that the pure protein LFBEP-C1 had the best lipid-lowering potential. Furthermore, our research found that LFBEP-C1 enriched the content of hydrophobic amino acids in LFBEP-C1. Ultraviolet spectroscopy analysis indicated that the glycosidic bond in LFBEP-C1 was an O-type glycosidic bond. The FTIR and circular dichroism spectra indicated that α-helix and random coil were the main secondary structures of LFBEP-C1. Mass spectrometry determined the theoretical molecular weight of LFBEP-C1 as 48 kDa, and its amino acid coverage was 63%. These findings suggest that the protein LFBEP-C1 with the best lipid-lowering activity was isolated and purified, and its structural characteristics were identified.

Structural Modification of Jackfruit Leaf Protein Concentrate by Enzymatic Hydrolysis and Their Effect on the Emulsifier Properties

Jackfruit leaf protein concentrate (LPC) was hydrolyzed by pepsin (H–Pep) and pancreatin (H–Pan) at different hydrolysis times (30–240 min). The effect of the enzyme type and hydrolysis time of the LPC on the amino acid composition, structure, and thermal properties and its relationship with the formation of O/W emulsions were investigated. The highest release of amino acids (AA) occurred at 240 min for both enzymes. H–Pan showed the greatest content of essential and hydrophobic amino acids. Low β-sheet fractions and high β-turn contents had a greater influence on the emulsifier properties. In H–Pep, the β-sheet fraction increased, while in H–Pan it decreased as a function of hydrolysis time. The temperatures of glass transition and decomposition were highest in H–Pep due to the high content of β-sheets. The stabilized emulsions with H–Pan (180 min of hydrolysis) showed homogeneous distributions and smaller particle sizes. The changes in the secondary structure and AA composition of the protein hydrolysates by the effect of enzyme type and hydrolysis time influenced the emulsifying properties. However, further research is needed to explore the use of H–Pan as an alternative to conventional emulsifiers or ingredients in functional foods.