Pea, Chickpea and Lentil Protein Isolates: Physicochemical Characterization and Emulsifying Properties

Effects of ultrasound on the structural, physicochemical, and emulsifying properties of aquafaba extracted from various legumes

This study investigated the effect of ultrasound (20-60 min, 40 kHz, 280 W) on the structural, physicochemical, and emulsifying properties of aquafaba extracted from various legumes (chickpea [CH], yellow soybean [YSB], black soybean [BSB], small black bean [SBB]). The hydrophobic amino acids and protein secondary structures (α-helix, random coil) significantly increased with sonication time (p < 0.05). The particle size of aquafaba was reduced by ultrasound (p < 0.05). A total of 27 volatile compounds were identified. Most volatiles increased with sonication time, and beany flavor was lowest in CH and SBB. The EAI, ESI, adsorbed proteins, and zeta-potential increased, while emulsion droplet size decreased in all legumes by ultrasound. The overall emulsifying properties were the highest in SBB sonicated for 40 min. This study discusses the applicability of ultrasound to aquafaba and provides insights into the functional properties and potential of aquafaba as a plant-based natural emulsifier.

The effect of pH shifting on the calcium-fortified milk analogue with chickpea protein

Milk alternative attracts more attention due to nutrition benefits, but the low solubility and the calcium deficiency of plant protein hinder the development of milk alternatives. Therefore, pH shifting was optimized to improve chickpea protein solubility and calcium fortification while ensuring good digestibility. The results showed that pH shifting reduced the particle size from 2197.67 ± 178.2 nm to 80.2 ± 2 nm, and increased the net ζ potential from -0.48 ± 0.24 to -21.27 ± 0.65 due to the unfolding of secondary protein structure, by which chickpea protein bring better solution stability. Additionally, the whiteness of the solution with chickpea protein increased. The calcium addition kept the solution stable with small particle size despite a slight increase. The microstructure of chickpea protein during digestion was well disrupted even with fortifying calcium. This study provides proof of the positive effect of pH shifting on chickpea protein stability and calcium fortification.

Understanding Stabilization of Oil-in-Water Emulsions with Pea Protein─Studies of Structure and Properties

This study investigates the stability and structure of oil-in-water emulsions stabilized by pea protein. Of the wide range of emulsion compositions explored, a region of stability at a minimum of 5% w/v pea protein and 30-50% v/v oil was determined. This pea protein concentration is more than what is needed to form a layer covering the interface. X-ray scattering revealed a thick, dense protein layer at the interface as well as hydrated protein dispersed in the continuous phase. Shear-thinning behavior was observed, and the high viscosity in combination with the thick protein layer at the interface creates a good stability against creaming and coalescence. Emulsions in a pH range from acidic to neutral were studied, and the overall stability was observed to be broadly similar independently of pH. Size measurements revealed polydisperse protein particles. The emulsion droplets are also very polydisperse. Apart from understanding pea protein-stabilized emulsions in particular, insights are gained about protein stabilization in general. Knowledge of the location and the role of the different components in the pea protein material suggests that properties such as viscosity and stability can be tailored for various applications, including food and nutraceutical products.

Microencapsulation of flaxseed oil in pea protein-gum arabic complex coacervates delays lipid digestion in liquid yoghurt

Flaxseed oil coacervates were produced by complex coacervation using soluble pea protein and gum arabic as shell materials, followed by either spray or electrostatic spray drying and their incorporation to yoghurt. Three yoghurt formulations were prepared: yoghurt with spray-dried microcapsules (Y-SD); with electrospray-dried microcapsules (Y-ES); with the encapsulation ingredients added in free form (Y). The standardised semi-dynamicin vitrodigestion method (INFOGEST) was employed to study the food digestion. The structure was analysed by confocal laser scanning microscopy and particle size distribution. Protein and lipid digestion were monitored by cumulated protein/free NH2 release and cumulated free fatty acids release, respectively. Stable microcapsules were observed during gastric digestion, but there was no significant difference in protein release/hydrolysis among samples until 55 min of gastric digestion. Formulation Y showed less protein release after 74 min (40.46 %) due to the free SPP being available and positively charged at pH 2-4, resulting in interactions with other constituents of the yoghurt, which delayed its release/hydrolysis. The total release of protein and free NH2 by the end of intestinal digestions ranged between 46.56-61.15 % and 0.83-1.57 µmol/g protein, respectively. A higher release of free fatty acids from formulation Y occurred at the end of intestinal digestion, implying that coacervates promoted the delayed release of encapsulated oil. In summary, incorporating protein-polysaccharides-based coacervates in yoghurt enabled the delay of the digestion of encapsulated lipids but accelerated the digestion of protein, suggesting a promising approach for various food applications.

Investigating the physicochemical, rheological, and sensory properties of low-fat mayonnaise prepared with amaranth protein as an egg yolk replacer

This study investigated the possibility of using amaranth protein isolate (API) as a plant-based substitute for egg yolk (EY) in the preparation of low-fat mayonnaise (LFM). The alkali extraction/acidic precipitation method was used to isolate amaranth protein; its functional properties were then studied. The results showed that besides its great water and oil absorption capacities, API had better emulsifying capacity and significantly higher (p < .05) emulsion stability at pH 2.0 than alkali pH values. Five mayonnaise samples with different API/EY combination ratios (%) (i.e., 0/0.75, 0.25/0.5, 0.375/0.375, 0.5/0.25, and 0.75/0) were prepared. The color, emulsion stability (ES), freeze-thaw stability (FTS), droplet size, structure, rheology, and sensory properties of samples were examined. API replacement showed no adverse effects on the L* value, ES, and sensory attributes (p > .05). Low API concentrations (0.25% and 0.375%) significantly (p < .05) increased the droplet size and decreased the FTS of LFM emulsion. High API concentrations (0.5% and 0.75%) had no significant effect (p > .05) on droplet size and formed emulsions with more tightly packed oil droplets. The Cross model was chosen best to describe the flow behavior of LFM samples (R 2 = 0.99). The sample with 0.75% API had significantly (p < .05) the highest values of η o (zero-shear viscosity) and λ (relaxation time), indicating greater interaction between the emulsion particles. All samples showed a weak gel structure (G' > G"). In conclusion, API can be considered an appropriate substitute for EY in LFM production, which can benefit human health and offer a new strategy for preparing vegan products.

The Application of Protein Concentrate Obtained from Green Leaf Biomass in Structuring Nanofibers for Delivery of Vitamin B12

Nanofibers made of natural proteins have caught the increasing attention of food scientists because of their edibility, renewability, and possibility for various applications. The objective of this study was to prepare nanofibers based on pumpkin leaf protein concentrate (LPC) as a by-product from some crops and gelatin as carriers for vitamin B12 using the electrospinning technique. The starting mixtures were analyzed in terms of viscosity, density, surface tension, and electrical conductivity. Scanning electron micrographs of the obtained nanofibers showed a slight increase in fiber average diameter with the addition of LPC and vitamin B12 (~81 nm to 109 nm). Fourier transform infrared spectroscopy verified the physical blending of gelatin and LPC without phase separation. Thermal analysis showed the fibers had good thermal stability up to 220 °C, highlighting their potential for food applications, regardless of the thermal processing. Additionally, the newly developed fibers have good storage stability, as detected by low water activity values ranging from 0.336 to 0.376. Finally, the release study illustrates the promising sustained release of vitamin B12 from gelatin-LPC nanofibers, mainly governed by the Fickian diffusion mechanism. The obtained results implied the potential of these nanofibers in the development of functional food products with improved nutritional profiles.

Unraveling the potential of non-thermal ultrasonic contact drying for enhanced functional and structural attributes of pea protein isolates: A comparative study with spray and freeze-drying methods

The challenge of preserving the quality of thermal-sensitive polymeric materials specifically proteins during a thermal drying process has been a subject of ongoing concern. To address this issue, we investigated the use of ultrasound contact drying (USD) under non-thermal conditions to produce functionalized pea protein powders. The study extensively examined functional and physicochemical properties of pea protein isolate (PPI) in powder forms obtained through three drying methods: USD (30 °C), spray drying (SD), and freeze drying (FD). Additionally, physical attributes such as powder flowability and color, along with morphological properties, were thoroughly studied. The results indicated that the innovative USD method produced powders of comparable quality to FD and significantly outperformed SD. Notably, the USD-PPI exhibited higher solubility across all pH levels compared to both FD-PPI and SD-PPI. Moreover, the USD-PPI samples demonstrated improved emulsifying and foaming properties, a higher percentage of random coil form (56.2 %), increased gel strength, and the highest bulk and tapped densities. Furthermore, the USD-PPI displayed a unique surface morphology with visible porosity and lumpiness. Overall, this study confirms the effectiveness of non-thermal ultrasound contact drying technology in producing superior functionalized plant protein powders, showing its potential in the fields of chemistry and sustainable materials processing.

Quality Characteristics of Vegan Mayonnaise Produced Using Supercritical Carbon Dioxide-Processed Defatted Soybean Flour

Emulsifiers, like egg yolk (EY), are necessary for the formation of mayonnaise, which is an oil-in-water type of colloid. This study aimed to assess the potential of defatted soybean powder treated with supercritical carbon dioxide (DSF) to enhance the quality of plant-based mayonnaise as plant-based alternatives gain popularity. This study involved the production of DSF and the comparison of its quality attributes to those of mayonnaise made with varying amounts of control soy flour (CSF), DSF, and EY. It was found that mayonnaise made with an increased quantity of DSF showed better emulsion stability, viscosity, and a smaller, more uniform particle size when compared with CSF mayonnaise. Additionally, DSF mayonnaise was generally rated higher in sensory evaluation. The addition of approximately 2% DSF positively influenced the emulsion and sensory properties of the vegan mayonnaise, indicating that DSF is a promising plant-based alternative emulsifier for the replacement of animal ingredients.

Viscoelastic behavior, gelation properties and structural characterization of Deccan hemp seed (Hibiscus cannabinus) protein: Influence of protein and ionic concentrations, pH, and temperature

This study investigates the viscoelastic behavior, gelling properties, and structural characteristics of Deccan hemp seed protein (DHSP) to overcome limitations in its application in food formulations. Small amplitude oscillatory shear measurements were employed to investigate the impact of protein concentration, pH, ionic concentration, and temperature on DHSP's rheological features. The study revealed that the 20 % protein dispersion had the highest storage modulus (G') and yield stress at 63.96 ± 0.23 Pa and 0.61 Pa, respectively. DHSP dispersion exhibited pseudo-plastic behavior across various conditions. The gelling performance was higher at pH 4 and 8 and at ionic concentration in the range of 0.1 M - 0.5 M. Gelation time and temperature were observed from the temperature ramp test. Structural characterizations, including fluorescence spectroscopy, circular dichroism spectra, FTIR spectra, SEM, AFM images, zeta potential analysis, and DSC, provided insights into DHSP's tertiary and secondary conformation, surface characteristics, and thermal properties. Notably, the study highlighted DHSP's exceptional rheological properties, making it a promising gelling material for the food and nutraceutical industries. The findings also offer new insights into DHSP's structural characteristics, suggesting potential applications in food packaging and product development within the food industry.

Pea protein [Pisum sativum] as stabilizer for oil/water emulsions

A map of stability for various water/oil/pea protein compositions has been plotted from the numerous reported results. Two clear regions of stability were identified. High internal oil phase emulsions with 70-80%, v/v oil content stabilized by total pea protein concentration <2.5%, w/v showed stability. Low oil content of 10-30%, v/v for a range of total pea protein concentrations >0.5%, w/v have also been identified as stable. Intermediate oil content and pea protein concentrations >4% w/v are unexplored regions and are likely to be areas of fruitful future research. The wide range of stability suggests that different stabilization mechanisms could be important for different compositions and careful consideration has to be taken to avoid oversimplification. Both stabilization with particles, i.e. Pickering emulsions, and protein unfolding have been suggested as mechanisms. The diverse way of describing stability makes it difficult to intercompare results in different studies. A summary of different oil types used have been presented and several properties such as dynamic viscosity, density, the dielectric constant and interfacial tension have been summarized for common vegetable oils. The type of vegetable oil and emulsion preparation techniques were seen to have rather little effect on emulsion stability. However, the different extraction methods and processing of the pea material had more effect, which could be attributed to changing composition of different proteins and to the states of aggregation and denaturing. Careful consideration has to be taken in the choice of extraction method and an increased understanding of what contributes to the stability is desirable for further progress in research and eventual product formulation.

A Study of Physical, Chemical, and Sensory Characteristics of Novel Legume Dips

There is a consensus among experts and consumers that pulses are a good source of nutrients and fiber. In a traditional hummus recipe, chickpeas are the major ingredient. The present study is aimed at developing new legume dips by exchanging chickpeas (Chd) with dry green (Gld) and red lentils (Rld), dry white beans (Wbd), and dry green peas (Gpd). Presoaking, boiling, proximate composition, pH, energy, color measurement, and sensory evaluation were conducted on the dips using chickpea dip (hummus) as a control. One-way ANOVA was used to determine the differences between the dips. The results revealed significant differences in the proximate composition of legume dips. The protein content of the five samples ranged between 7.46% and 9.19%, while the values varied from 8.59% to 10.93% in fat, 3.88% to 6.54% in crude fiber, 14.48% to 15.51% in carbohydrates, 171.95 to 195.13 in energy, 1.55% to 1.76% in ash, and 63.35% to 66.90% in moisture. These variations could be attributed to the type and composition of each legume, the soaking and boiling process, and the tahini added during the preparation. pH ranged between 4.5 and 4.7. The color measurement indicated that the five legume dips could be considered bright products (high L∗>67), with a positive color valuebluered-green and yellow-. Significant differences (p ≤ 0.05) were observed in the legume dips sensory evaluation, and the red lentil dip was the most acceptable with results comparable to the chickpea dip; it was followed by the green lentil, white bean, and green pea dips. These results highlight the feasibility of commercial production of legume dip that promotes human health and gives consumers more choices.

Effects of nitrogen fertilizer on the physicochemical, structural, functional, thermal, and rheological properties of mung bean (Vigna radiata) protein

Nitrogen fertilizer can affect the seed quality of mung bean. However, the effects of nitrogen fertilizer on the properties of mung bean protein (MBP) remain unclear. We investigated the effects of four nitrogen fertilization levels on the physicochemical, structural, functional, thermal, and rheological properties of MBP. The results showed that the amino acid and protein contents of mung bean flour were maximized under 90 kg ha-1 of applied nitrogen treatment. Nitrogen fertilization can alter the secondary and tertiary structure of MBP. The main manifestations are an increase in the proportion of β-sheet, the exposure of more chromophores and hydrophobic groups, and the formation of loose porous aggregates. These changes improved the solubility, oil absorption capacity, emulsion activity, and foaming stability of MBP. Meanwhile, Thermodynamic and rheological analyses showed that the thermal stability, apparent viscosity, and gel elasticity of MBP were all increased under nitrogen fertilizer treatment. Correlation analysis showed that protein properties are closely related to changes in structure. In conclusion, nitrogen fertilization can improve the protein properties of MBP by modulating the structure of protein molecules. This study provides a theoretical basis for the optimization of mung bean cultivation and the further development of high-quality mung bean protein foods.

Characterization of yeast protein isolates extracted via high-pressure homogenization and pH shift: A promising protein source enriched with essential amino acids and branched-chain amino acids

In the global food industry, plant-based protein isolates are gaining prominence as an alternative to animal-based counterparts. However, their nutritional value often falters due to insufficient essential amino acids. To address this issue, our study introduces a sustainable protein isolate derived from yeast cells, achieved through high-pressure homogenization (HPH) and alkali pH-shifting treatment. Subjected to HPH pressures ranging from 60 to 120 MPa and 1 to 10 cycles, higher pressure and cycle numbers resulted in enhanced disruption of yeast cells. Combining HPH with alkali pH-shifting treatment significantly augmented protein extraction. Four cycles of HPH at 100 MPa yielded the optimized protein content, resulting in a yeast protein isolate (YPI) with 75.3 g protein per 100 g powder, including 30.0 g of essential amino acids and 18.4 g of branched-chain amino acids per 100 g protein. YPI exhibited superior water and oil-holding capacities compared to pea protein isolate, whey protein isolate (WPI), and soy protein isolate. Although YPI exhibited lower emulsifying ability than WPI, it excelled in stabilizing protein-stabilized emulsions. For foaming, YPI outperformed others in both foaming ability and stabilizing protein-based foam. In conclusion, YPI surpasses numerous plant-based protein alternatives in essential amino acids and branched-chain amino acids contents, positioning it as an excellent candidate for widespread utilization as a sustainable protein source in the food industry, owing to its exceptional nutritional advantages, as well as emulsifying and foaming properties. PRACTICAL APPLICATION: This study introduces a sustainable protein isolate derived from yeast cells. YPI exhibited considerable promise as a protein source. Nutritionally, YPI notably surpassed plant-based protein isolates in EAA and BCAA contents. Functionally, YPI demonstrated superior water-holding and oil-holding capacities, as well as an effective emulsion and foam stabilizer.

Thermo-induced changes in the structure of lentil protein isolate (Lens culinaris) to stabilize high internal phase emulsions

This study aims to assess the impact of heat treatment on the emulsifying properties of lentil protein isolate (LPI) dispersion to produce high internal phase emulsions (HIPEs). The heat-treated LPI dispersion was characterized by size, turbidity, solubility, zeta potential, free sulfhydryl group, electrophoresis, differential scanning calorimetry, circular dichroism, Fourier transforms infrared spectroscopy and intrinsic fluorescence. HIPEs were produced with 25% of LPI dispersion (2%, w/w) and soybean oil (75%) using a rotor-stator (15,500 rpm/1 min). HIPEs were evaluated for their droplet size, zeta potential, centrifugal stability, microscopy, appearance, Turbiscan stability, and rheology over 60 days (25 °C). Heat treatment reduced the size of LPI, resulting in increased turbidity, solubility, and exposure of hydrophobic groups. HIPEs produced with heat-treated LPI at 70 °C (HIPE70) and 80 °C (HIPE80) for 20 min exhibited lower droplet sizes, increased stability, reduced oil loss, and a homogeneous appearance compared to HIPE produced with untreated LPI (HIPEc). In addition, HIPE70 and HIPE80 displayed resistance to shear stress, higher apparent viscosity, and increased storage modulus than HIPEc. HIPEs produced with heat-treated LPI were stable, suggesting that the treatment was efficient for improving the functional properties of the protein and the possibility of future research focusing on fat substitutes in food applications.

Transglutaminase-Induced Polymerization of Pea and Chickpea Protein to Enhance Functionality

Pulse proteins, such as pea and chickpea proteins, have inferior functionality, specifically gelation, compared to soy protein, hindering their applications in different food products, such as meat analogs. To close the functionality gap, protein polymerization via targeted modification can be pursued. Accordingly, transglutaminase-induced polymerization was evaluated in pea protein isolate (PPI) and chickpea protein isolate (ChPI) to improve their functionality. The PPI and ChPI were produced following a scaled-up salt extraction coupled with ultrafiltration (SE-UF) process. Transglutaminase (TGase)-modified PPI and ChPI were evaluated in comparison to unmodified counterparts and to commercial protein ingredients. Protein denaturation and polymerization were observed in the TG PPI and TG ChPI. In addition, the TGase modification led to the formation of intermolecular β-sheet and β-turn structures that contributed to an increase in high-molecular-weight polymers, which, in turn, significantly improved the gel strength. The TG ChPI had a significantly higher gel strength but a lower emulsification capacity than the TG PPI. These results demonstrated the impact of the inherent differences in the protein fractions on the functional behavior among species. For the first time, the functional behavior of the PPI and ChPI, produced on a pilot scale under mild processing conditions, was comprehensively evaluated as impacted by the TGase-induced structural changes.

Properties of texturized protein and performance of different protein sources in the extrusion process: A review

The need for protein is increasing due to the rapid growth of the global population. However, conventional animal meat production has caused severe environmental, land usage, and other issues. Meat substitutes can provide consumers with a high-quality alternative to protein. Texturized protein (TP) is a critical ingredient in meat substitutes and is mainly obtained through extrusion processing. Therefore, this review first discussed the essential physical properties of TP, including appearance and structure, water-holding capacity (WHC) and oil-holding capacity (OHC), texture, and sensory properties. The performance of plant and novel source proteins in extrusion processing is also summarized. The properties of the desired TP should be considered first before extrusion processing. Under different extrusion parameters, proteins from the same source can exhibit varying properties. Although the novel source proteins can adversely affect TP quality, their high yield and environmental protection are worthy of further study. This paper aims to review the impact of proteins from different sources on the properties of TP during the extrusion process and discuss practical research methods for TP.

Assessing the emulsifying properties of Tenebrio molitor larvae protein preparations: Impact of storage, thermal, and freeze-thaw treatments on o/w emulsion stability

Insect proteins have gained attention as novel ingredients, which may contribute to the development of high-value-added products. This study evaluates the emulsifying and emulsion-stabilizing properties of Tenebrio molitor larvae protein preparations obtained through different procedures, leading to the following rich-in-protein samples: ASP (∼67 %), AIP (∼75 %), and SSP (∼62 %). The method applied for protein isolation influenced the molecular and structural characteristics of the preparations, thus affecting their adsorption behaviour at oil-water interfaces and ability to stabilize emulsions. O/w emulsions were prepared, and their physicochemical stability was assessed with respect to droplet size, oil droplet flocculation/coalescence, microstructure, and creaming upon storage as well as after thermal and freeze-thaw treatments. The use of ASP and AIP protein preparation as emulsifiers led to higher stability during storage. All emulsions were stable upon heating and able to withstand two freeze-thaw cycles without phase separation, although there was an increase in droplet size. Interestingly, the AIP emulsion remained stable after the 3rd freeze-thaw cycle, indicating remarkable stability under freezing compared to the other two emulsions. These findings are of great importance for the formulation of food-grade emulsions using insect protein preparations and their future exploitation in developing food items subjected to different treatments.

The Stability, Rheological Properties and Interfacial Properties of Oil-in-Water (O/W) Emulsions Prepared from Dielectric Barrier Discharge (DBD) Cold Plasma-Treated Chickpea Protein Isolate and Myofibrillar Protein Complexes

In order to increase the development and utilization of chickpea protein isolate (CPI) and improve the stability of myofibrillar protein (MP) emulsions, the effect of dielectric barrier discharge (DBD) plasma-modified CPI on the emulsifying properties of MP was investigated. Three different O/W emulsions were prepared using MP, MP + CPI complex, or MP + DBD-treated CPI complex as the emulsifier. Compared with the emulsion prepared from MP, the emulsifying activity index and stability of DBD-treated CPI and MP complex (MP + CPIDBD) were increased (p < 0.05) from 55.17 m2/g to 74.99 m2/g and 66.31% to 99.87%, respectively. MP + CPIDBD produced more stable emulsions with the lowest Turbiscan stability index (TSI) values for a given 3600 s. At shear rates from 0 to 1000-1, MP + CPIDBD-stabilized emulsions had higher viscosities, which helped to reduce the chance of aggregation between oil droplets. The optical microscope and particle size distribution of emulsions showed that MP + CPIDBD emulsions had the lowest droplet size (d4,3) and exhibited more uniform distribution. MP + CPIDBD emulsions had lower interfacial tension. DBD pretreatment increased the adsorbed protein content in the emulsion stabilized by MP + CPIDBD as compared to the MP + CPI complex and promoted the adsorption of CPI by higher ratios of adsorbed proteins as indicated by its intensity in SDS-PAGE. Scanning electron microscopy confirmed that the emulsion prepared from MP + CPIDBD had smaller particle size and more uniform dispersion. Therefore, using DBD-modified CPI could enhance the stability of MP emulsions.

Comparative study on molecular and higher-order structures of legume seed protein isolates: Lentil, mungbean and yellow pea

Lentils and mungbean proteins are under-researched compared to pea and soybean. Lentils (green, red and black-lentils), mungbean and yellow pea protein isolates were obtained by alkaline extraction (pH 9)-isoelectric precipitation (pH 4.5) and investigated for molecular and higher-order structures using complementary and novel approaches. These extracted isolates showed comparable protein content but significantly greater nitrogen solubility index (NSI > 85 %) than commercial pea and soy protein isolates (NSI < 60 %). Based on molecular weight estimations from sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis, the soluble proteins of lentils and yellow pea were identified as legumin-like and vicilin-like, while mungbean was dominated by vicilin-like proteins. The soluble extracts were confirmed to be in native structural condition by size exclusion chromatography and nano-differential scanning calorimetry, unlike commercial extracts. Further differences in secondary structure were evident on circular dichroism spectra of the soluble extracts and deconvolution of the Amide I region (1700-1600 cm-1) from Fourier Transform Infrared of the total protein.

Effects of pH and Ionic Strength in Calcium on the Stability and Aeration Characteristics of Dairy Emulsion

The effects of different pH levels and ionic strength in calcium on the stability and aeration characteristics of dairy emulsions were investigated in this study. The results revealed that the stability and aeration characteristics of the emulsion were enhanced as the pH value increased from 6.5 to 7.0 and were optimal within the pH of 6.8~7.0, while the concentration of free calcium ions (Ca²⁺) was 2.94~3.22 mM. With the pH subsequently fixed at 6.8 and 7.0, when the addition of CaCl₂ was increased to 2.00 mM (free Ca²⁺ strength > 4.11 mM), stability and aeration characteristics reduced significantly, including the flocculation of fat globules, an increase in particle size, and a decrease in the zeta potential and viscosity of the O/W emulsion, all leading to an increase in interfacial protein mass and decreased overrun and foam firmness. Overall, the results indicated that pH changes and CaCl₂ addition significantly influenced the stability and aeration characteristics of dairy emulsions, by influencing free Ca²⁺ strength, which is an important factor in determining the quality of dairy emulsions.

Inducing the structural interplay of binary pulse protein complex to stimulate the solubilization of chickpea (Cicer arietinum L.) protein isolate

Chickpea protein (CP) is an exceptional nutrient-dense pulse protein prevailing in the development of plant-based foods. However, its relatively low solubility, compared to other legume proteins, hinders the practical uses of CP in food matrix. To resolve this problem, pea protein (PP), another popular pulse protein, was co-assembled with CP to form a binary complex during the alkaline pH-shifting process. Results indicated that the complexed CP exhibited significantly increased solubility to that of the pristine protein (more than 50%), whose aqueous stability was also enhanced against different environmental stresses (pH, salt, heat/frozen treatment, and centrifugation). Structural and morphology analysis confirmed the interplay between unfolded CP and PP during pH shifting, which enabled their resistance to acid-induced structural over-folding. Our experiments that induce the co-assembling of two pulse proteins provide a novel routine and scientific basis for tailoring CP functionalities, as well as the formulation of pulse protein-based products.

Isoflavone Content and Nutritional-Related Properties of Debittered Seeds from Two Andean Lupin (Lupinus mutabilis Sweet) Ecotypes Propagated in Two Soils

Lupinus mutabilis Sweet is a fabaceous plant native to the Andean highlands and produces seeds with valuable nutritional properties. Thus, as part of our research on native emerging food, the present study aimed at determining some nutritional and functional-related features of seeds from two L. mutabilis ecotypes after propagation in two different substrates commonly found in the Bogotá plateau. Propagated plants produced seeds that, after conventional debittering, exhibited attractive contents of soluble protein (24-39 g/100 g dry seed powder (dsp)), phenolic (787-1003 g/100 g dsp), isoflavone (1-104 g/100 g dsp), and iron (5.3-6.4 g/100 g dsp), as well as antioxidant capacity (39-78 µM/100 g dsp). Higher pH, humidity saturation, organic matter, and total nitrogen of silty loam soil promoted isoflavone accumulation and better antioxidant capacity at pH 4-7, and no soil effect was observed for total phenolic and iron contents. The profiles based on isoflavone aglycones were also recorded by liquid chromatography-mass spectrometry, detecting eleven main compounds with mutabilein as the most abundant isoflavone (38.3-104.3 g/100 g dsp). Finally, a formulation was developed to fabricate an emulsion-type drink based on the debittered, pulverized L. mutabilis seeds, resulting in different emulsifying capacities (19-100%) depending on the biopolymer stabilizer, being xanthan gum the best additive. The findings revealed an attractive Andean lupin profile to be used as a raw food material.

Salt Solubilization Coupled with Membrane Filtration-Impact on the Structure/Function of Chickpea Compared to Pea Protein

The demand for pulse proteins as alternatives to soy protein has been steeply increasing over the past decade. However, the relatively inferior functionality compared to soy protein is hindering the expanded use of pulse proteins, namely pea and chickpea protein, in various applications. Harsh extraction and processing conditions adversely impact the functional performance of pea and chickpea protein. Therefore, a mild protein extraction method involving salt extraction coupled with ultrafiltration (SE-UF) was evaluated for the production of chickpea protein isolate (ChPI). The produced ChPI was compared to pea protein isolate (PPI) produced following the same extraction method in terms of functionality and feasibility of scaling. Scaled-up (SU) ChPI and PPI were produced under industrially relevant settings and evaluated in comparison to commercial pea, soy, and chickpea protein ingredients. Controlled scaled-up production of the isolates resulted in mild changes in protein structural characteristics and comparable or improved functional properties. Partial denaturation, modest polymerization, and increased surface hydrophobicity were observed in SU ChPI and PPI compared to the benchtop counterparts. The unique structural characteristics of SU ChPI, including its ratio of surface hydrophobicity and charge, contributed to superior solubility at both a neutral and acidic pH compared to both commercial soy protein and pea protein isolates (cSPI and cPPI) and significantly outperformed cPPI in terms of gel strength. These findings demonstrated both the promising scalability of SE-UF and the potential of ChPI as a functional plant protein ingredient.

Enzymatic hydrolysis of soy and chickpea protein with Alcalase and Flavourzyme and formation of hydrogen bond mediated insoluble aggregates

Food applications involving plant proteins require modification of their functionality to mimic the unique properties of animal proteins. Enzymatic hydrolysis is commonly used to alter the functionality of plant proteins, particularly to improve their solubility near the isoelectric point. Current methodological approaches mostly indicate improved solubility upon hydrolysis. However, published methods include the removal of insoluble material before analysis, and calculations are based on only the solubilized material as a percentage of the filtered protein. This approach artificially increases solubility estimation and gives an incorrect assessment of the efficacy of hydrolysis. By using the total amount of protein, this study aims to determine the effect of two microbial proteases, Flavourzyme and Alcalase, on the solubility and structural and thermal properties of soy and chickpea proteins. Protein isolates were first extracted from soy and chickpea flour and hydrolyzed from 0 to 3 h. Then, their degree of hydrolysis and solubility at a range of pHs were determined using the o-phthaldialdehyde (OPA) and Lowry methods, respectively. Proteins' electrophoretic mobility, protein-protein interactions, thermal properties, and protein secondary structures were also determined. Solubility decreased over time though the solubility of the hydrolysate improved near the isoelectric point. Soy Flavourzyme hydrolysates remained the most soluble and chickpea Flavourzyme hydrolysates showed the least solubility. Thermal data suggested that Alcalase reduced the protein denaturation temperature, leading to a loss of solubility upon thermal enzyme inactivation. The loss of solubility of hydrolysates was strongly associated with hydrogen bonding, which may result from the formation of polar peptide termini. These results challenge commonly accepted beliefs that hydrolysis inevitably improves solubility of plant proteins. Instead, it is shown that hydrolysis causes structural changes that result in aggregation, thus potentially limiting the application of enzymatic hydrolysis without the addition of further processing methods.

Enhancement of pea protein solubility and thermal stability for acidic beverage applications via endogenous Maillard-induced glycation and chromatography purification

A clean-label process to endogenously glycate and purify pea protein was investigated. The production of maltodextrin from pea starch with a specific dextrose equivalent (DE) was optimized. The produced maltodextrin (14.6 DE) was used to initiate a limited and controlled Maillard-induced glycation of pea protein. The partially glycated pea protein (PG-PP) was subjected to hydrophobic interaction chromatography to remove unreacted carbohydrate, followed by characterization of the purified product. The extent of Maillard-induced glycation was monitored by assessing changes in color, free amino groups, and protein/glycoprotein profiles. The purified PG-PP was evaluated for thermal denaturation, surface properties, protein secondary structure, protein solubility, thermal stability, and digestibility. Maillard-induced glycation was limited to initial stages and resulted in a moderate blockage of amine groups (∼30%). The purified PG-PP had a relatively low surface hydrophobicity, a markedly enhanced protein solubility (∼90%) at pH 3.4, and a nonimpacted protein in vitro digestibility (∼100%). This work provided the impetus needed for future scale-up and process optimization for the production of value-added pea protein ingredient intended for high protein beverage applications.

Encapsulation of Cumin (Cuminum cyminum L.) Seed Essential Oil in the Chickpea Protein-Maltodextrin Matrix

Isoelectrically precipitated chickpea protein isolate (CPI) and its combination with maltodextrin (MD) were investigated for the ability to form and stabilize cumin seed oil emulsions. Solubility, net surface charge, emulsion activity/stability indices, and creaming stability of CPI at a pH of 3.0-9.0 were evaluated. Optimum conditions for minimum cream separation were identified as: 0.19% CPI and 6.83% oil concentrations. Cumin (Cuminum cyminum L.) seed essential oil was microencapsulated within the CPI-MD matrix via spray drying. Effects of CPI-MD matrix formulation on the physicochemical characteristics and volatile composition of the microencapsules were investigated. CPI-MD matrices had positive effects on microcapsule properties such as relatively lower surface oil, higher encapsulation efficiency (EE), and oil retention. Approximately 86.6-96.4% oil retention and 90.9-98.4% EE were achieved. Optimum conditions for maximized oil retention (92.9%) and EE (98.6%) were identified as: 2.1% CPI, 14.8% essential oil, and 35% MD. GC-MS analysis of microcapsules was carried out to determine the changes in volatile composition during spray drying. Cymene, α-pinene, β-pinene, sabinene, terpinene, terpineol, phellandrene, and cumin aldehyde were determined as the major components. Optimized design showed the highest EE and minimal changes in the volatile composition of cumin seed essential oil.

The Impact of High-Intensity Ultrasound-Assisted Extraction on the Structural and Functional Properties of Hempseed Protein Isolate (HPI)

Hempseed protein has become a promising candidate as a future alternative protein source due to its high nutritional value. In the current study, hempseed protein isolate (HPI) was obtained using ultrasonic-assisted extraction with the aim to improve the functionality of HPI via protein structure modification. The solubility of HPI could be improved twofold under 20 kHz ultrasound processing compared to conventional alkaline extraction-isoelectric point precipitation. The protein solubility was gradually enhanced as the ultrasonic power improved, whereas excessive ultrasound intensity would cause a decline in protein solubility. Ultrasonic processing was found to have beneficial effects on the other functionalities of the extracted HPI, such as emulsifying and foaming properties. This improvement can be ascribed to the physical effects of acoustic cavitation that changed the secondary and tertiary structures of the protein to enhance surface hydrophobicity and decrease the particle size of the extracted protein aggregates. In addition, more available thiols were observed in US-treated samples, which could be another reason for improved functionality. However, the results of this study also revealed that prolonged high-power ultrasound exposure may eventually have a detrimental impact on HPI functional properties due to protein aggregation. Overall, this study suggests that high intensity ultrasound can enhance the functionality of HPI, which may ultimately improve its value in HPI-based food products.

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.

Interfacial Properties of Pea Protein Hydrolysate: The Effect of Ionic Strength

The effect of a tryptic hydrolysis as well as the effect of ionic strength (0–0.4 M NaCl) was investigated on the oil/water interfacial properties of soluble pea protein hydrolysate (SPPH) at neutral pH and room temperature (20 ± 0.01 °C). SEC-MALS and SDS-Page analysis showed that tryptic hydrolysis created a lower molecular weight polypeptide mixture, whereas FTIR analysis and DSC thermograms demonstrated a more disordered and flexible structure. The bulk properties of SPPH were studied in terms of hydrodynamic diameter and turbidity, where higher particle size (+ ~13 nm) and turbidity were observed at 0.4 M NaCl. Regarding the interfacial properties, the surface activity of SPPH improved by increasing ionic strength, with maximum interfacial pressure (14.28 mN/m) at 0.4 M NaCl. Nevertheless, the addition of NaCl negatively affected the elasticity and strength of the interfacial film, where the sample without salt exhibited the highest dilatational and shear storage modulus in all the frequencies considered.

Actinidin in Green and SunGold Kiwifruit Improves Digestion of Alternative Proteins—An In Vitro Investigation

Both Hayward (green) and SunGold (gold) kiwifruit varieties contain a proteolytic enzyme, actinidin, that has been reported to enhance the upper tract digestion of animal proteins. Unlike the other gold varieties, which do not contain any actinidin, the SunGold variety contains significantly higher actinidin activity, but its activity is still much lower than that present in the green (Hayward) fruit. The objective of this study was to determine the effectiveness of actinidin in Hayward and SunGold kiwifruit in digesting alternative proteins, including pea protein, almonds, tofu, and quinoa. The protein sources were digested using a three-stage in vitro oral-gastro-small intestinal digestion model. The findings showed that both kiwifruit extracts enhanced the breakdown (observed through SDS-PAGE) for all the studied protein sources, particularly during gastric digestion, possibly due to higher actinidin activity at gastric pH. The increase in the rate of protein breakdown was probably due to the broader specificity of actinidin compared to pepsin. For many protein sources, most of the intact proteins disappeared within the first few minutes of gastric digestion with added kiwifruit extract. Green kiwifruit extract, due to its higher actinidin activity, had a higher effect on protein breakdown than the SunGold extract. However, for some proteins and under certain digestion conditions, SunGold extract resulted in higher protein breakdown. The latter, in the absence of any digestive enzymes, also led to some protein breakdown during the small intestinal digestion phase, which was not the case for the green kiwifruit extract. The green kiwifruit extract led to the greater breakdown of polypeptide chains of Pru-du 6, a major allergen in almonds. The results, for the first time, suggest that both Hayward and SunGold kiwifruit can lead to improved breakdown and digestion of alternative proteins when consumed as part of a meal; and therefore, have the potential to be used as a digestive aid in population groups looking to achieve faster and greater protein digestion such as athletes, elderly and people with the impaired digestive system.

Legume Seed Protein Digestibility as Influenced by Traditional and Emerging Physical Processing Technologies

The increased consumption of legume seeds as a strategy for enhancing food security, reducing malnutrition, and improving health outcomes on a global scale remains an ongoing subject of profound research interest. Legume seed proteins are rich in their dietary protein contents. However, coexisting with these proteins in the seed matrix are other components that inhibit protein digestibility. Thus, improving access to legume proteins often depends on the neutralisation of these inhibitors, which are collectively described as antinutrients or antinutritional factors. The determination of protein quality, which typically involves evaluating protein digestibility and essential amino acid content, is assessed using various methods, such as in vitro simulated gastrointestinal digestibility, protein digestibility-corrected amino acid score (IV-PDCAAS), and digestible indispensable amino acid score (DIAAS). Since most edible legumes are mainly available in their processed forms, an interrogation of these processing methods, which could be traditional (e.g., cooking, milling, extrusion, germination, and fermentation) or based on emerging technologies (e.g., high-pressure processing (HPP), ultrasound, irradiation, pulsed electric field (PEF), and microwave), is not only critical but also necessary given the capacity of processing methods to influence protein digestibility. Therefore, this timely and important review discusses how each of these processing methods affects legume seed digestibility, examines the potential for improvements, highlights the challenges posed by antinutritional factors, and suggests areas of focus for future research.

Study on model plant based functional beverage emulsion (non-dairy) using ultrasound - A physicochemical and functional characterization

This study reports the development of non-dairy functional beverage emulsion employing ultrasound (US) of 20 kHz at 130 W and 195 W at processing times of 2 to 8 min using chickpea milk extract and bioactive, flaxseed oil (4%). The pre-emulsion was formed with high shear homogenizer followed by main sonication process. The sonicated emulsions were stored at 4 ± 2 °C till 14 days and characterized for physicochemical and functional properties. A comparative study was carried out using conventional high shear homogenizer (UT) at 10,000 RPM for 5 min. Upon optimization, 130 W - 8 min, 195 W - 6 min and 195 W - 8 min sono-emulsions showed creaming stability of 100%; with particle sizes as 1.12, 0.97 and 0.78 µm; and zetapotential values as - 40.4 mV, -37.52 and -36.91 mV, respectively. The improvement in protein solubility by 86% proved the emulsifying capability of chickpea proteins, which had partially denatured upon physical effects of acoustic cavitation producing stable and finer emulsion droplets. The reduced sedimentation values of sonicated chickpea extract in comparison to UT showed improvement in physical stability of plant-based milk. Oxidative stability is observed for 130 W - 8 min sonicated emulsions with no change in conjugated dienes, indicating the absence of process generated free radicals. The US process did not have any effect on reduction of stachyose content. But extracted chickpea milk had lower amount of stachyose in comparison to raw chickpeas, reducing the flatulence problem, mainly due to adaptation of high temperature pressure cooking process.

Effects of enzymatic cross-linking combined with ultrasound on the oil adsorption capacity of chickpea protein

In order to improve the oil adsorption capacity of chickpea protein, enzymatic cross-linking combined ultrasound was used to modify chickpea protein. Electrophoretic results showed that enzymatic cross-linking made the protein bands thinner, but ultrasound had no significant effect. The oil adsorption capacity of chickpea protein increased from 1.88 to 2.43 g/g; the surface hydrophobicity increased from 3933 to 4575; the zeta potential and emulsification performance were improved.After enzymatic cross-linking, the content of the free sulfhydryl group and emulsifying stability were decreased, and the particle size and the content of disulfide bonds were increased.After ultrasonic treatment, these properties showed an opposite trend. Fourier Transform Infrared Spectroscopy showed that β-turn and random coil increased, the structure of protein became more loose and disordered. These results indicate that enzymatic cross-linking combined with ultrasound improves the functional properties of chickpea protein and extends its application.

The Protein-Rich Powdered Beverages Stabilized with Flax Seeds Gum—Antioxidant and Antiproliferative Properties of the Potentially Bioaccessible Fraction

The functional beverages market is one of the fastest-growing sectors of functional food production. An innovative recipe for powdered fruit and vegetable drinks fortified with lentil proteins (AGF) and stabilized with flax seed gums (FSG) was developed. The study focused on the analysis of potentially bioaccessible fractions from the produced beverages in terms of their antioxidant, antiproliferative activities and physicochemical properties. The contents of bioactive components were tailored by the incorporation of lyophilized fruits and vegetables, the FSG and the AGF. Digestion in vitro effectively released phenolics from all matrices. The highest contents of potentially bioavailable polyphenols were recorded for the AGF based beverages enriched with 5% of FSG and green-leafy vegetables (58 mg/100 mL) and those with lyophilized fruit (54 mg/100 mL). The reducing power of the beverages was mainly affected by the presence of the AGF, while the FSG and lyophilized fruit improved the chelating power. The digests applied in the concentrations mimicking physiological concentrations showed antiproliferative properties against gastric and colon adenocarcinoma—they seemed to be tailored by bioactive peptides and phenolics, respectively. The addition of the FSG improved the stability of the beverages increasing the time required for a reduction of 20% of the initial optical density by 16- and 28-times in the beverages without additives or enriched with vegetables. Both, the AGF and FSG stabilize the beverages after rehydration and are sources of bioaccessible antioxidant and anticancer components, which create their functionality.

A Narrative Review of Alternative Protein Sources: Highlights on Meat, Fish, Egg and Dairy Analogues

The research and development of alternatives to meat (including fish) and dairy products for human consumption have been increasing in recent years. In the context of these alternatives, there is a diversity of products such as tofu, tempeh, seitan, pulses, algae, seeds, nuts and insects. Apart from these, some products require new technical processes such as needed by milk drink alternatives, mycoprotein and meat, cheese and fish analogues. The aim of these analogues is to mimic the physical and organoleptic properties of animal origin products through fibrous composition and mix of ingredients from vegetable sources using adequate technology, which allow providing similar texture and flavor. Using a narrative approach to review literature, the objectives of this paper are to systematize the arguments supporting the adoption of meat, eggs and dairy alternatives, to identify the diversity of alternatives to these products on the market, including the related technological processes, and to project the challenges that the food industry may face soon. From a total of 302 scientific papers identified in databases, 186 papers were considered. More research papers on products associated with alternatives to milk were found. Nevertheless, there are products that need more research as analogues to meat and dairy products. A general scheme that brings together the main reasons, resources and challenges that the food industry faces in this promising area of alternatives to meat and dairy products is presented.