Lentil Protein Research Articles

Enhanced Oligopeptide and Free Tryptophan Release from Chickpea and Lentil Proteins: A Comparative Study of Enzymatic Modification with Bromelain, Ficin, and Papain.

Plant-based foods offer a sustainable alternative to meet the growing protein demand. Legumes are the most promising of these, as they contain relatively high concentrations of protein, low digestible starch, and dietary fiber, as well as them possibly featuring low levels of fat. Enzymatically modified legume proteins provide us with tempting perspectives in terms of enhancing foods' biological values. However, their bioavailability and digestibility are generally less sufficient than that of proteins of animal origin, which may be improved by well-tailored enzyme modification. In this study, the efficacy of three plant-based proteases (bromelain, ficin, and papain) were evaluated at two distinct concentrations (2.5% and 10%) and three hydrolysis durations (1, 2, and 12 h) when transforming chickpea and lentil proteins. The degree of hydrolysis (DH), peptide profiles, and free amino acid content were analyzed to determine the efficiency of each enzyme. Results showed significant variations in DH, which was influenced by enzyme type, concentration, and hydrolysis duration. Papain exhibited the highest DH, particularly at a 10% concentration, reaching 27.8% efficiency in chickpea and 34.8% in lentils after 12 h. Bromelain and ficin were proven to be less effective, with ficin showing the least hydrolytic activity. SDS-PAGE analysis revealed substantial protein degradation, especially subsequent to papain treatment, pointing out that most proteins were cleaved into smaller peptides. SEC-HPLC indicated a predominant release of peptides within the 200-1000 Da range, suggesting enhanced bioavailability. Papain and bromelain treatments resulted in a significant release of oligopeptides and dipeptides. UHPLC analysis highlighted a marked post-hydrolysis increase in total free amino acids, with arginine, leucine, and lysine being the most abundant ones. Notably, tryptophan, being undetectable in untreated samples, was released in measurable amounts post-hydrolysis. These findings demonstrate papain's superior performance in protein hydrolysis and its potential in producing bioactive peptides, highlighting its applicability in food processing and the development of both nutraceuticals and functional foods.

Lentil protein and trehalose conjugates: Structural interactions and mechanisms for improving multi-level structure and functional characteristics.

This study aimed to improve lentil proteins' (LPs) functionality and nutritional value, specifically addressing their lower water solubility and digestibility. A unique combination of LP-disaccharide interactions was employed. Spectroscopic technologies, which include fluorescence spectra, ultraviolet spectra, and Fourier-transform infrared, investigated the structure of LPs at various concentrations of trehalose. The results indicate that the LP structures and conformation were considerably modified (p<0.05) following trehalose conjugation. The surface charge and hydrophobicity of the trehalose-conjugated LPs (T-LPs) were significantly altered (p<0.05), from -22.7 to -31.4 and 753 and 543 a.u., respectively. Furthermore, the digestibility and solubility of T-LPs increased from 75% to 81.8% and 60% to 66%, respectively. In conclusion, this study showed that combining LPs and trehalose conjugation could improve the quality of conjugates LPs, which could expand their use in manufacturing as the acceptance of plant-based diets increases. PRACTICAL APPLICATION: Currently, lentil proteins (LPs) are used in plant-based protein powders and supplements. Though less popular than soy or pea proteins, LPs are valued for their high protein content and good amino acid profile. LPs are utilized in meat alternatives and high-protein snack products. The application of these products is mainly due to their nutritional benefits rather than functional properties due to their poor water solubility. Increasing the water solubility of LPs could significantly expand their application in various food industries, making LPs a more competitive and functional plant-based protein source. Trehalose-conjugated LPs with better water solubility allow LPs to be used in other food products, such as plant-based protein beverages. Better solubility would enhance the clarity and smoothness of these products, making them more appealing to consumers.

Enhancing a Vegan Snack Bar: Edible Coating Infused with Lentil Protein and Pomegranate Peel

Enhancing a Vegan Snack Bar: Edible Coating Infused with Lentil Protein and Pomegranate Peel

Comparative study of interaction and complex formation of Tremella fuciformis polysaccharide with whey protein, lentil protein, and soy protein isolates

The electrostatic interactions and complex formation of Tremella fuciformis polysaccharide (TPS) with whey protein (WPI), lentil protein (LPI), and soy protein (SPI) isolates were studied. The molecular size and components in each protein isolate complexed with TPS were characterized, along with the structural changes in the protein components, induced by TPS complexation. The stability of emulsions prepared with protein:TPS complexes was also evaluated (pH 4.5). Compared to WPI, the LPI and SPI protein components exhibited more negative charges and larger molecular sizes. Independent of the isolate type, pHc of all protein:TPS systems remained unchanged and pHɸ1 shifted to higher pHs as the protein/TPS ratio increased; the pHopt of WPI:TPS and SPI:TPS occurred at higher values as the protein/TPS ratio increased, while the pHopt of LPI:TPS system was less dependent on the biopolymer mixing ratio, probably due to the lower solubility of LPI. Protein components such as β-LG in WPI, convicilin, vicilin, and basic legumin in LPI, and α’ subunits of 7S β-conglycinin and acidic subunits of 11S glycinin in SPI might be the main components interacting with TPS for complex formation. Different proteins exhibited distinct trends in changing their secondary structural elements when interacting with TPS. At pH 4.5, a high proportion of TPS increased the stability of protein emulsion, regardless of the protein used. The WPI:TPS emulsions with low content of TPS were highly destabilized due to the formation of insoluble WPI:TPS complex coacervates, a phenomenon not observed in emulsions stabilized by the LPI:TPS or SPI:TPS systems.

Structural, techno‐functional and nutraceutical properties of lentil proteins – a concise review

SummaryLentil is one of the major pulses consumed in many parts of the world. Lentil proteins comprise primarily three fractions, viz. globulins, albumins and glutelins, each having distinct structural and functional characteristics. The secondary structure of lentil proteins is characterised by a predominance of β‐sheets, which occur in proportions up to 63% in the fractions. Protein isolates, in comparison, have up to 40% random coils, 38% sheets, 36% turns and 33% helix. Lentil proteins contain most essential amino acids, while albumins and glutelins have relatively higher content of lysine, methionine, histidine, threonine and branched‐chain amino acids. Amongst globulin proteins, vicilins have a more balanced amino acid composition than legumins. Lentil proteins also exhibit techno‐functional properties (foaming and emulsification, water and fat absorption and gelation) and may also serve as a potential source of active proteins/peptides, which make them an attractive alternative to conventional protein sources.

Effect of the Structural Modification of Plant Proteins as Microencapsulating Agents of Bioactive Compounds from Annatto Seeds (Bixa orellana L.).

This project studied the use of lentil protein (LP) and quinoa protein (QP) in their native and modified states as carrier material in the encapsulation process by the ionic gelation technique of annatto seed extract. Soy protein (SP) was used as a model of carrier material and encapsulated bioactive compounds, respectively. The plant proteins were modified by enzymatic hydrolysis, N acylation, and N-cationization to improve their encapsulating properties. Additionally, the secondary structure, differential scanning calorimetry (DSC), solubility as a function of pH, isoelectric point (pI), molecular weight (MW), the content of free thiol groups (SH), the absorption capacity of water (WHC) and fat (FAC), emulsifier activity (EAI), emulsifier stability (ESI), and gelation temperature (Tg) were assessed on proteins in native and modified states. The results obtained demonstrated that in a native state, LP (80.52% and 63.82%) showed higher encapsulation efficiency than QP (73.63% and 45.77%), both for the hydrophilic dye and for the annatto extract. Structural modifications on proteins improve some functional properties, such as solubility, WHC, FAC, EAI, and ESI. However, enzymatic hydrolysis on the proteins decreased the gels' formation, the annatto extract's encapsulated efficiency, and the hydrophilic dye by the ionic gelation method. On the other hand, the modifications of N-acylation and N-cationization increased but did not generate statistically significant differences (p-value > 0.05) in the encapsulation efficiency of both the annatto extract and the hydrophilic dye compared to those obtained with native proteins. This research contributes to understanding how plant proteins (LP and QP) can be modified to enhance their encapsulating and solubility properties. The better encapsulation of bioactive compounds (like annatto extract) can improve product self-life, potentially benefiting the development of functional ingredients for the food industry.

Application of high-pressure homogenization-assisted pH-shift to enhance techno-functional and interfacial properties of lentil protein isolate

High-pressure homogenization (HPH) is a promising physical non-thermal approach to improve protein techno-functionality. This study aims to examine the effects of HPH on the lentil proteins through the perspective of the interfacial adsorption mechanism. The impact of HPH treatment on lentil protein isolate (LPI) at varying pressure levels (0–150 MPa) was determined using several analytical techniques, including SDS-PAGE, FTIR, solubility, and techno-functional properties (foaming and emulsifying properties), alongside analyses of interfacial tension and interfacial shear rheology at the o/w and a/w interfaces for two pH values (2.0 and 4.5). Results reveal that HPH treatment up to 100 MPa effectively unfolds lentil proteins by disrupting disulfide-bonded subunits into lower molecular weight fractions and unfolding highly-ordered secondary structures into random coils. LPI's capacity to produce emulsions and foams was found to be enhanced concurrently with these physicochemical changes, particularly at pressures up to 50 MPa. The findings aligned with the interfacial tension and shear rheology analyses, which show that proteins can form interfacial viscoelastic films on both o/w and a/w interfaces. Furthermore, the interfacial behavior of LPI and the effect of HPH on the interfacial behavior were found to be pH-dependent. The lower interfacial tension and the higher interfacial viscoelastic moduli (G′ and G″) were recorded at 50 MPa and 0 MPa at pH 2.0 and 4.5, respectively. These results stated that the effects of the HPH on the technofunctionality of LPI can be further enlightened by investigating the interfacial adsorption kinetics.

Enhancing the quality of lentil proteins via combination with whey proteins based on a dual process: a novel strategy through the incorporation of complexation and fermentation

Enhancing the quality of lentil proteins via combination with whey proteins based on a dual process: a novel strategy through the incorporation of complexation and fermentation

Molecular, interfacial and foaming properties of pulse proteins

Pulses are important protein sources in the current protein transition, but much of the behavior of pulse proteins in food systems (e.g. foam) is still unknown. This study compared the similarities and differences of the proteins from three common pulses: lentil, faba bean, and chickpea, at the molecular, mesoscopic and functionality levels. For each source, the proteins were extracted with a simple one-pot alkaline extraction, resulting in protein extracts with high protein content (67–85%) rich in globulins (68–81%) and albumins (19–32%). All pulse protein fractions were predominantly in a native state with high solubilities (83–91%), high denaturation enthalpies (8.9–10.1 J/(g protein)) and low aggregation levels. Lentil protein showed higher absolute value of the ζ-potential (−18.5 ± 1.2 mV) than faba bean (−13.2 ± 0.8 mV) and chickpea protein (−12.4 ± 1.2 mV). The behavior of all pulse proteins at the air-water interface including adsorption kinetics, interfacial dilatational rheology and interfacial microstructure was investigated and linked to their foaming properties. The pulse protein with the highest vicilin and convicilin content (39.5% in lentil protein) showed the shortest adsorption lag time (300 ms), and demonstrated the highest foam overrun (290 ± 17%). All three pulse protein fractions formed interfaces with disordered solid-like behavior and consisted of heterogeneous network structures. These structures were mostly comprised of intact globulin proteins for lentil and faba bean proteins, while mixtures of intact globulins and unfolded proteins/albumins were observed for chickpea protein. The interfacial stiffness, interfacial density and ζ-potential of these pulse proteins showed a high positive correlation with their foam stabilization properties. Lentil protein has the highest values of those parameters and showed the longest foam half-life time of 115 (± 22) min, while faba bean and chickpea proteins showed comparably lower values of those parameters and shared similarly shorter foam half-life times of 46 (± 19) min and 38 (± 6) min, respectively. These findings can aid to provide clearer directions in screening pulse proteins for desirable performance in aerated food products.

Processing parameters, techno-functional properties and potential food application of lentil protein concentrate as an ingredient for the plant-based market

Lentil (Lens culinaris) is a protein-rich legume consumed worldwide and it also has the potential to become an alternative source of protein ingredient for human nutrition. The aim of this study was to determine the best processing parameters for the whole grain protein wet extraction, as well as to analyze the techno-functional properties, and physical characteristics of the protein concentrate and its flour. It was also evaluated the application of the concentrate into a fish-like croquette. The processing route was carried out by alkaline extraction and acid precipitation of the proteins where the pH, stirring time and solute:solvent ratio were evaluated. The final dried protein concentrate presented 85% protein on dry basis and a mass yield of 14%. The results were reproducible when tested on a first scaling up test. For the techno-functional properties, solubility, water and oil retention capacities, emulsification and foaming capacities and stability, and gelling capacity were tested. As for the food application into fish-like croquettes, the lentil protein showed similar scores for sensory acceptance, flavor and texture when compared to a commercial clean-taste concentrate. The results observed in this study were compatible to other alternative pulse-protein ingredients on the market, positioning lentil protein as a promising alternative protein source to produce ingredients for the plant-based market.

Combination of legume proteins and arabinoxylans are efficient emulsifiers to promote vitamin E bioaccessibility during digestion

The emulsification potential of plant-based emulsifiers, that is, pea (PPI) and lentil (LPI) proteins (4%), corn arabinoxylans (CAX, 1%), and legume protein-arabinoxylan mixtures (4% proteins + 0.15 or 0.9% CAX), was evaluated by assessing: the surface tension and potential of emulsifiers, emulsifier antinutritional contents, emulsion droplet size, emulsion physical stability, and vitamin E bioaccessibility from 10% oil-in-water emulsions. Tween 80 (2%) was used as a control. All emulsions presented small droplet sizes, both fresh and upon storage, except 4% LPI + 0.9% CAX emulsion that exhibited bigger droplet sizes (d(4,3) of approximately 18.76 μm vs 0.59 μm for the control) because of droplet bridging. Vitamin E bioaccessibility from emulsions stabilized with the combination of 4% PPI and either 0.15% or 0.9% CAX (28 ± 4.48% and 28.42 ± 3.87%, respectively) was not significantly different from that of emulsions stabilized with Tween 80 (43.56 ± 3.71%), whereas vitamin E bioaccessibility from emulsions stabilized with individual emulsifiers was significantly lower.

Submerged fermentation of lentil protein isolate and its impact on protein functionality, nutrition, and volatile profiles.

Fermentation of pulses as a clean processing technique has been reported to have a favorable impact on the functional and nutritional quality of the starting materials. Compared to commonly fermented pulses such as peas and chickpeas, limited information is available on the effect of fermentation on lentils, especially when using a high protein isolate (>80% protein) as compared to seeds or flours. Therefore, in the present work, lentil protein isolate was used as a feedstock for submerged fermentation with Aspergillus niger, Aspergillus oryzae, or Lactobacillus plantarum. After 48h, the samples showed increased protein content with enhanced solubility and oil-holding capacity. Controlled fermentation, as opposed to spontaneous fermentation, maintained the high foaming capacity; however, all fermented samples had lower foam and emulsion stabilizing properties and reduced water-holding capacity compared to the control. The fermented proteins were also less digestible, possibly due to an increase in phenolics and saponins. New volatile compounds were identified in fermented samples that show promise for improved sensory attributes. Significant differences were observed in specific quality attributes depending on the microbial strain used. Further research is required to better understand the fermentative metabolism of microbial communities when provided high-protein lentil ingredients as growth substrates. PRACTICAL APPLICATION: Fermented lentil protein isolate has promising flavor profiles that may improve its sensory properties for food application.

Interfacial rheological properties of pepsin-hydrolyzed lentil protein isolate at oil-water interfaces

Lentil protein isolate (LPI) was investigated for its potential as a plant protein-based emulsifier. LPI consists mainly of globulins with high molecular weights which are relatively slow to adsorb and stabilize oil-water interfaces. Smaller proteins, such as whey protein, can stabilize the interface much faster, quickly forming a viscoelastic film that slows down the rate of droplet recoalescence, leading to smaller droplets. To increase the rate of adsorption, LPI was enzymatically hydrolyzed by pepsin at 1.5% and 4.5% degree of hydrolysis (DH), to obtain small peptides. The behavior of these peptides was studied at the oil-water interface in comparison to whey protein isolate (WPI) and native lentil protein isolate (LPI). Interfacial properties were investigated using dilatational and interfacial shear rheology in the linear viscoelastic regime (LVE) and nonlinear viscoelastic regime (NLVE) and these were related to protein characteristics and emulsion formation. The 1.5% and 4.5%DH LPI showed high surface hydrophobicity, and consisted mainly of low molecular weight peptides, which contributed to faster adsorption kinetics and consequently covered the interface faster than LPI. In dilatation, the native and hydrolyzed LPI-stabilized interfaces had comparable stiffness and were clearly weaker than WPI-stabilized interfaces, which contrasts with the results in shear deformations, where the former both had higher stiffness than WPI. Both hydrolyzed LPI and WPI formed more brittle and less stretchable interfaces compared to native LPI in both dilatational and shear rheology. In emulsification tests, native LPI produces the largest droplets, and the 4.5% DH LPI and WPI have the smallest droplet size. But, bridging flocculation was observed when emulsions were prepared with both hydrolyzed LPI, which may be attributed to inter-droplet hydrophobic interactions between small polypeptides. This can be linked to an increase in the surface hydrophobicity of hydrolyzed LPI. Thus, the use of native LPI as a stabilizer in emulsion preparation is preferable over the hydrolyzed samples, despite its larger droplet size.

Fibrillization of lentil proteins is impacted by the protein extraction conditions and co-extracted phenolics

Legume proteins can be induced to form amyloid-like fibrils upon heating at low pH, with the exact conditions greatly impacting the fibril characteristics. The protein extraction method may also impact the resulting fibrils, although this effect has not been carefully examined. Here, the fibrillization of lentil protein prepared using various extraction methods and the corresponding fibril morphology were characterized. It was found that an acidic, rather than alkaline, protein extraction method was better suited for producing homogeneous, long, and straight fibrils from lentil proteins. During alkaline extraction, co-extracted phenolic compounds bound proteins through covalent and non-covalent interactions, contributing to the formation of heterogeneous, curly, and tangled fibrils. Recombination of isolated phenolics and proteins (from acidic extracts) at alkaline pH resulted in a distinct morphology, implicating a role for polyphenol oxidase also in modifying proteins during alkaline extraction. These results help disentangle the complex factors affecting legume protein fibrillization.

Lentil protein isolate (Lens culinaris) subjected to ultrasound treatment combined or not with heat-treatment: structural characterization and ability to stabilize high internal phase emulsions

This study evaluated the effect of ultrasound treatment combined or not with heat treatment applied to lentil protein isolate (LPI) aiming to enhance its ability to stabilize high internal phase emulsions (HIPE). LPI dispersion (2%, w/w) was ultrasound-treated at 60% (UA) and 70% (UB) amplitude for 7 min; these samples were subjected to and then heat treatments at 70 °C (UAT70 and UBT70, respectively) or 80 °C (UAT80 and UBT80, respectively) for 20 min. HIPEs were produced with 25% untreated and treated LPI dispersions and 75% soybean oil using a rotor–stator (15,500 rpm/1 min). The LPI dispersions were evaluated for particle size, solubility, differential scanning calorimetry, electrophoresis, secondary structure estimation (circular dichroism and FT-IR), intrinsic fluorescence, surface hydrophobicity, and free sulfhydryl groups content. The HIPEs were evaluated for droplet size, morphology, rheology, centrifugal stability, and the Turbiscan test. Ultrasound treatment decreased LPI dispersions’ particle size (∼80%) and increased solubility (∼90%). Intrinsic fluorescence and surface hydrophobicity confirmed LPI modification due to the exposure to hydrophobic patches. The combination of ultrasound and heat treatments resulted in a reduction in the free sulfhydryl group content of LPI. HIPEs produced with ultrasound-heat-treated LPI had a lower droplet size distribution mode, greater oil retention values in the HIPE structure (> 98%), lower Turbiscan stability index (< 2), and a firmer and more homogeneous appearance compared to HIPE produced with untreated LPI, indicating higher stability for the HIPEs stabilized by treated LPI. Therefore, combining ultrasound and heat treatments could be an effective method for the functional modification of lentil proteins, allowing their application as HIPE emulsifiers.

Enhancing emulsifying properties of lentil protein fibrils through EGCG mediation and the mechanism study

Amyloid-like fibrils derived from plant proteins has provided a strategy to improve plant protein physicochemical performance and has substantial untapped potential for application in stabilizing oil-in-water (O/W) emulsions. This study aimed to explore the structural modifications of lentil protein fibrils (LPF) and their emulsifying properties facilitated by EGCG, with the proposal of potential underlying mechanism. The structure and morphology of LPF-EGCG complexes were characterized by particle size, Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, surface hydrophobicity, contact angle, and transmission electron microscope (TEM). Results showed that the binding of LPF to EGCG was driven by hydrogen bonding and hydrophobic interaction. Both interactions play a pivotal role in the cross-linking of LPF and the transformation of the elongated fibrillar morphology of LPF into fibrillar aggregates networks, and even large-sized non-amyloid fibril aggregates, with particle size increasing from 564 nm to 3221 nm. Droplet size and confocal laser scanning microscopy (CLSM) results showed that the O/W emulsions containing 30% and 50% (w/w) oil stabilized by LPF-EGCG complex (EGCG-to-protein ratio, EGCG/P = 0.04) exhibited smallest and uniform droplet sizes (9.25 μm and 11.50 μm, respectively). The reason was that an appropriate concentration of EGCG can fine-tune the hydrophobic/hydrophilic balance and network structures of LPF, thus enhancing the stability of emulsions. Moreover, emulsions containing 30% (w/w) oil stabilized by LPF-EGCG complexes (EGCG/P > 0.02) exhibited rheological behavior similar to emulsions containing 50% oil stabilized by LPF alone, indicating potential applications in the production of fat reduced emulsion with desirable textures. These findings provide a new perspective on the structural remodeling of plant-based protein fibrils mediated by phenolic compounds, expanding their application in the production of fat-reduced emulsion-based food products.

Interaction and complex formation of sonicated soluble lentil protein and Tremella fuciformis polysaccharide

Proteins’ physicochemical and structural properties critically affect their interactions with polysaccharides. The effect of ultrasound treatment (0–40 min) on the physicochemical properties of soluble lentil proteins (LPs) was investigated. The interaction between LPs (ultrasound-treated for different times, U0-LP, U5-LP, and U40-LP) and Tremella fuciformis polysaccharides (TPS) under different pHs, biopolymer mixing ratios, and total biopolymer concentrations was studied. With the sonication duration increasing, decreased intrinsic fluorescence, higher zeta potential values, and increased hydrophilicity were observed for the sonicated LP samples. The molecule weight of LPs remained unchanged, and their secondary structure changes were independent of the sonication duration. The soluble LPs:TPS complexes and insoluble complex coacervates formed at pH 6.5 (pHc) and pH 6.0 (pHɸ1), respectively, regardless of the mixing ratio and the LP type. The maximum formation of insoluble LPs:TPS complex coacervates (pHopt) occurred at the biopolymer mixing ratio of 4:1 at pH 3.0, 2:1 at pH 3.0, and 2:1 at pH 3.5 for the U0-LP:TPS, U5-LP:TPS, and U40-LP:TPS systems, respectively. The pHɸ1 and pHopt of all the three LPs:TPS systems shifted to higher pH values as the total biopolymer concentration increased. With the greatest dynamic quenching constants (Ksv) and binding site (n) values, U40-LP exhibited the strongest binding affinity with TPS. This was consistent with the highest viscosity of their mixture solution under pHs greater than pHopt. The overall results suggest that ultrasound-treated proteins showed a stronger electrostatic interaction with TPS compared to untreated proteins.

Trehalose-conjugated lentil-casein protein complexes prepared by structural interaction: Effects on water solubility and protein digestibility

The two limiting factors for lentil protein utilization are water solubility and digestibility. In this study, we utilized two non-thermal techniques: (1) protein complexation of lentil and casein proteins using the pH-shifting method and (2) protein conjugation with trehalose to produce trehalose-conjugated lentil-casein protein complexes (T-CPs) with enhanced water solubility and digestibility. The protein structure of the T-CPs was analyzed for secondary protein structure, conformation protein, and tertiary protein structure using Fourier-transform infrared, UV, and fluorescence spectroscopies, respectively. The surface hydrophobicity and surface charge of T-CPs solution at pH 7.0 changed significantly (P < 0.05). Using these two non-thermal techniques, the water solubility and digestibility of T-CPs increased significantly (P < 0.05) by 85 to 89 % and 80 to 85 %, respectively. The results of this study suggested that these non-thermal techniques could enhance the surface and protein structure properties, improving water solubility and digestibility.

Effects of extrusion screw speed, feed moisture content, and barrel temperature on the physical, techno-functional, and microstructural quality of texturized lentil protein.

Utilizing lentil protein as a novel ingredient for producing texturized vegetable proteins (TVPs) can provide new opportunities for the production of next-generation hybrid meat products. TVPs from lentil protein isolate were manufactured using low-moisture extrusion cooking at different combinations of screw speed (SS), feed moisture content (MC), and barrel temperature (BT) profile. In total, seven different combinations of processing treatments were tested, and the resulting TVPs were characterized for their physical (rehydration ratio, texture profile analysis, color, and bulk density), techno-functional (oil and water holding capacities), and microstructural properties. The processing conditions of higher SS and lower MC resulted in increased values of several textural profile attributes (springiness, cohesiveness, and resilience), increased water holding capacity (WHC), and decreased bulk density. Compared to raw lentil protein, TVPs showed enhanced oil holding capacity, though WHC either decreased or remained constant. The extrusion response parameters (die pressure, torque, and specific mechanical energy) showed positive correlations with several physical properties (texture, WHC, and total color change), revealing their potential for serving as important TVP quality indicators. TVPs produced at SS, MC, and BT of 450rpm, 30%,and 140°C, respectively, showed relatively better overall physical and techno-functional quality and can be used as meat extenders in hybrid meat patties. Overall, this research evidenced the viability of lentil protein as a potential ingredient for producing low-moisture TVPs.

Unveiling the contribution of Osborne protein fractions to the physicochemical and functional properties of alkaline and enzymatically extracted green lentil proteins

AbstractLentil proteins are gaining popularity as food ingredients, serving both functional and nutritional purposes. To better understand the properties of lentil proteins extracted using commercially relevant methods (alkaline and enzymatic), sequential fractionation by solubility (Osborne fractionation) was performed and the physicochemical, thermal, and functional properties of the extracts were characterized. Fractionation revealed that 43% of lentil proteins were water‐soluble (ALB, albumin‐rich), 37% salt‐soluble (GLO, globulin‐rich), 14% alkaline‐soluble (GLU, glutelin‐rich), and 3% ethanol‐soluble (PRO, prolamin‐rich). Protein extraction yields of 81% and 87% were achieved by alkaline (pH 9.0, 50 °C, 1:10 solids‐to‐liquid ratio, 60 min) and enzymatic extraction (same conditions with 0.5% (w/w) Alkaline Protease), respectively. Proteomic analysis allowed for the identification of 129 proteins among all extracts, and the ALB and GLO fractions exhibited similar protein profiles as the alkaline‐extracted proteins. The secondary structure of the protein fractions was dominated by β‐sheets (20%–35%) and unordered structures (45%–48%). Surface hydrophobicity and absolute zeta potential were negatively correlated (R2 = 0.82, p &lt; 0.05). ALB and GLO fractions had higher denaturation temperatures than the alkaline/enzymatically‐extracted proteins, potentially due to partial denaturation. ALB and GLO fractions also had the highest solubility and emulsification capacities. Under acidic conditions, enzymatically‐extracted proteins exhibited better solubility (58 vs. 33%), emulsification (499 vs. 403 g oil/g dry sample), and similar foaming capacity (57%–69%) compared to alkaline‐extracted proteins. This study showed that alkaline and enzymatically extracted lentil proteins share physicochemical and functional characteristics with water‐ and salt‐extracted proteins, demonstrating the efficacy of these single‐stage extraction strategies in achieving high yields and desirable functionality.