Bean Protein Isolate Research Articles

Protein Extractability and Thermally Induced Gelation Properties of African Locust Bean Proteins (Parkia biglobosa Jacq. R.Br)

African locust bean (AfLB) protein isolates could be an interesting alternative to the use of soy as an ingredient for the development of new protein-rich products. From AfLB seed flour, the protein extractability yields by aqueous extraction were determined as a function of pH and ionic strength. Then thermally induced gelation of various protein suspensions relating to protein concentration was studied. The most critical factors affecting extractability were the pH and the presence of fat. As a function of the extraction process, the extraction yield of protein from AfLB flour ranged from 30 to 65%. Two major fractions of proteins detected in AfLB seeds were albumins and globulins, comprising four families: legume-like protein, vicilin-like proteins, convicilin, and albumins. The globulin isolate had the lowest solubility at pH 3.5-4 and the highest at pH 8-10. The solubility of albumin isolate was lightly affected by pH and ionic strength. At pH 7, the minimum protein concentration for thermal gel formation ranged from 55 to 120 g/L as function purified state of proteins. The less purified extract with a simpler process made it possible to obtain a gel needing a lower protein concentration. This last way seems promising to the development of new foods based on African locust bean flour.

Quality characteristics of chicken sausages using a combination of jack bean (Canavalia ensiformis L.) and soy protein isolate as a binder

Jack beans are one of the legumes with a high protein content to make protein isolates. This research aimed to evaluate the physical, sensory and proximate qualities of chicken sausages with jack bean protein isolate (JBPI) and the combination of JBPI and soy protein isolate (SPI) as a binder to improve the quality of the chicken sausages. This research included the preparation of JBPI and chicken sausages. The treatments were formulated as follows: control (without JBPI and SPI); T1 (SPI: JBPI = 100: 0); T2 (SPI: JBPI = 80:20); T3 (SPI: JBPI = 60:40); T4 (SPI: JBPI = 40: 60); T5 (SPI: JBPI = 20: 80); T6 (SPI: JBPI = 0: 100). The analysis of the physical, sensory, and proximate properties of sausages have been performed. The results showed that the JBPI protein content was high at 93.98% db, and contained higher essential amino acids than the FAO/WHO standards, i.e., leucine, lysine, phenylalanine + tyrosine, threonine. The combination of JBPI and SPI improved emulsion stability, lightness, yellowness, texture properties, protein content, and reduced cooking loss and redness of chicken sausages compared to control (p<0.05). The results of the sensory evaluation showed that the overall preference, slice properties, and texture attributes of chicken sausage with the addition of a combination of SPI and JBPI were 40:60 (T4) significantly different from the control received by the panellists (p<0.05). The formulation with the addition of a combination of SPI and JBPI of 40:60 was the optimal treatment because it improves the overall physical, sensory, and chemical characteristics of the resulting chicken sausage. JBPI had the potential as an alternative to substitution for SPI.

Effect of ultrasound-assisted alkaline treatment on functional property modifications of faba bean protein

This study investigated alkaline shifting, ultrasonication, and their combination on functional modifications of faba bean protein isolate (FPI). The protein characterization revealed that the combined alkaline shifting/ultrasound treatment dissociated large aggregates of FPI into small ones, resulting in increased protein surface hydrophobicity and decreased free sulfhydryl groups. Such structural changes significantly increased FPI solubility from 12.2 to 40.4% to more than 95% at pH 3 and 7 and more than 80% at pH 6. Furthermore, the FPI modified by the combined alkaline shifting/ultrasound treatment produced emulsions with smaller particle size and superior stability at pH values 3 and 7. Likewise, a striking enhancement in foaming capacity (from 93% to 306–386%) and stability (from 10 s to 473–974 s) was achieved by the combined treatment. This study suggested that the ultrasound-assisted alkaline shifting treatment could be considered an effective method for improving FPI functional properties.

Investigation of functional and antioxidant properties of Faba bean protein hydrolysates using combined hydrolysis

Background and objectives: Food is considered not only as a source of energy and essential ingredients for growth and health but also as a source of bioactive compounds that can have beneficial effects in humans. Bioactive peptides are considered to be functional compounds that have been recognized in foods recently. An enzymatic hydrolysis has been used to improve the functional properties of plant proteins. One of the features of the protein hydrolysates is their antioxidant activity, which makes it possible to use them as antioxidant agents in food models. In this study, the effect of using different enzymes and their combination in production of protein hydrolysates with high functional and antioxidant properties was investigated. Material and methods: Faba bean protein isolate was enzymatically hydrolyzed by trypsin and alcalase alone, and in a successive way with trypsin and alcalase at concentrations of 1.5 and 3%, and optimum temperature of 37 and 50 °C and pH of 7 and 8.5 respectively all at the reaction time of 3h. The solubility parameters at pH 2-12, foaming and foam stability at the pH level of 4, 6, 8 and 10, DPPH radical scavenging activity, and iron chelating activity of protein hydrolysates were investigated. Results: The results showed that enzymatic hydrolysis increased the solubility, especially in acidic pH range. At pH 3, the protein hydrolysates derived from alcalase and the combination of trypsin and alcalase enzymes at the concentration of 3% had the highest solubility (64.51% and 60.95% respectively). Foaming capacity increased with increasing of pH from 4 to 8. The highest foaming capacity was observed at pH level of 8, but at pH level of 10, in all samples, foaming capacity decreased. Protein isolate at pH level of 4 created no foam after 60 minutes. The highest foam stability was observed at pH level of 8 in all samples. The results also showed that hydrolysis of faba bean protein significantly increased the foaming stability (p 0.05). The enzymatic hydrolysis significantly increased the iron chelating activity compared to the faba bean protein isolate (P <0.05). Conclusion: The results showed that different enzymes under constant hydrolysis conditions have different effects on a single substrate. Enzymatic modification of proteins creates a natural antioxidant source in food models, which can increase the shelf life of products.

Substantial Depletion of Vicine, Levodopa, and Tyramine in a Fava Bean Protein-Based Nutritional Product.

A commercial fava bean protein isolate and a liquid nutritional product formulated with it were tested by validated HPLC methods for the favism-associated pyrimidine glycoside vicine, the dopamine precursor levodopa, and the biogenic amine tyramine. The vicine, levodopa, and tyramine concentrations in the protein isolate—306, 13.3, and <0.5 mg/kg, respectively—when expressed on a protein basis—34, 1.5, and <0.06 mg/100 g protein, respectively—were at least 96% lower than the vicine, levodopa, and tyramine (protein-based) concentrations reported for fava beans (≥900, ~200, and ~4 mg/100 g protein, respectively). This was also true for the vicine (13 mg/kg or 22 mg/100 g protein), levodopa (≤0.17 mg/kg or ≤0.3 mg/100 g protein), and tyramine (0.08 mg/kg or 0.14 mg/100 g protein) concentrations in the nutritional product. On the basis of these data, one serving (11 fl. oz.) of the nutritional product would deliver approximately 5 mg of vicine, <1 mg of levodopa, and <0.1 mg of tyramine.

Faba bean meal, starch or protein fortification of durum wheat pasta differentially influence noodle composition, starch structure and in vitro digestibility

Faba bean (Vicia faba L.) flour, starch concentrate (60% starch), protein concentrate (~60% protein) and protein isolate (~85% protein) were added to replace one-quarter of durum wheat semolina to enrich the nutritional quality and physiological functions of durum wheat (Triticum turgidum L.) pasta. The raw pasta samples prepared with protein concentrate or isolate had higher (p ≤ 0.001) protein and lower (p ≤ 0.001) total starch concentrations, along with increased total dietary fiber and slowly digestible starch (p ≤ 0.001) than durum wheat semolina control or those with added whole faba-bean flour or isolated starch. The faba bean fortified pasta had altered starch with increased proportion of medium B-type glucan chains and long C-type glucan chains, reduced starch digestibility and were associated with glycaemia related effects in the human diet. The faba bean fortified pasta had increased protein and dietary fiber that influenced food intake and satiety. The results suggest differential contributions of food ingredients in human health outcomes.

Combined effect of cassava starch nanoparticles and protein isolate in properties of starch‐based nanocomposite films

AbstractThis study aimed to evaluate the effects of incorporation of cowpea protein isolate and cassava starch nanoparticles obtained by ultrasound on the properties of cassava starch:glycerol films. The cowpea bean protein isolate was successfully obtained with 72.5% of protein and solubility about 90%. The cassava starch nanoparticles yielded 97.85%. Increasing protein isolate concentration in starch:glycerol films resulted in a progressive reduction of water vapor permeability up to 27.0%. The cassava starch nanoparticles added films presented expressive increments in tensile strength (283.83%) as well as modulus of elasticity (204.31%), accompanied by decreasing in elongation at break (24.28%). The thermal stabilities of cassava starch films were affected by the addition of both protein isolate and cassava starch nanoparticles. The cassava starch nanoparticles obtained by ultrasound ensured the maintenance of film properties, optimizing the production time, with a higher yield, and without the need for chemical reagents. Thus, it could be useful for substitution of those obtained by acid hydrolysis. Therefore, giving rise to a trend of production of nanocomposite films suitable for reinforced packaging applications.

Enhancing quality and safety of raw buffalo meat using the bioactive peptides of pea and red kidney bean under refrigeration conditions

The aim of this study was to extend the shelf life of raw buffalo meat by coating with high solubility bioactive peptides (BPs). In this work, BPs (11S) of pea and red kidney beans were obtained by different isolation techniques. Alcalase-red kidney bean hydrolysate (RBAH) successfully obtained after 60 min enzymatic hydrolysis for red kidney bean protein isolate (RPI) by Alcalase (E/S ratio of 1:100, hydrolysis degree 30%). The 11S pea globulin (11SGP) was isolated from pea total protein by ammonium sulphate. BPs were characterised by SDS-PAGE and used as a shield coated raw buffalo meat because of their basic nature. The isolated peptides have considerable antioxidant and antimicrobial activity. The antioxidant activity was estimated by DPPH assay. The antibacterial activity was evaluated by well diffusion assay; however, antifungal activity was estimated by disc diffusion assay. RBAH and 11SGP (800 µg/mL) were significantly (p ≤ .05) scavenged 90, 92% of DPPH˙, however, 60 µg/mL concentration was significantly (p ≤ .05) reduced 48–89% of gram-positive, and 38–82% of gram-negative bacteria, respectively, and they were inhibited 88% of fungal growth. The BPs (400 µg/g) were significantly reduced (p ≤ .05) the increment of meat pH and myoglobin oxidation to an acceptable percentage of metmyoglobin (MetMb) (40%) for 15–20 d via eliminating 44% of bacterial load and maintained secured storage for two weeks. RBAH was significantly increased (p ≤ .05) a*, and b* values and enhanced the meat redness, but a* value was decreased during storage. RBAH and 11SGP (400 µg/g) (p ≤ .05) was maintained the meat colour and odour by 48–68% and 64–73% after two weeks of cold storage, respectively. The tested peptides could be safely applied in novel foods. Highlights 11SGP and RBAH are high solubility bioactive peptides (BPs) with antioxidant and antimicrobial activity. 11SGP and RBAH reduce myoglobin oxidation to an acceptable percentage of met-myoglobin. RBAH enhances the whiteness and redness of buffalo meat. 11SGP and RBAH extend meat shelf life for a period exceeds 15 d at 4 °C. Graphical

Pinto bean protein-based acid-induced cold-set gels as carriers for curcumin delivery: Fabrication and characterization

In this study, a new acid-induced cold-set gel based on pinto bean protein isolate (PBI) was developed, and then its textural, morphological, rheological, and physical properties were evaluated. Textural and rheological properties of the gels improved when protein and glucono-delta-lactone (GDL) concentrations were increased. Acid-induced gels showed a disordered structure of aggregates. The water holding capacity (WHC) of the gels increased significantly (p<0.05) from 85 to 86% to 92–96% when the protein concentration increased from 5% to 7%. The gel fabricated with 7% protein and 15% GDL indicated better mechanical and rheological properties; hence it was selected for curcumin entrapment and further evaluations. According to circular dichroism (CD) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results, the pre-heating process at pH ∼ 7.3 ± 0.08 allowed to fabricate thermally aggregated PBI (TA-PBI). The pre-heating process caused a significant increase in particles diameter (p<0.05), but surface hydrophobicity decreased (p<0.05). PBI cold-set gel presented an excellent embedding potential (98.54%) at a curcumin concentration of 0.7 mg/mL. Fluorescence spectroscopy indicated that curcumin was attached to PBI. The results of confocal laser scanning microscopy (CLSM) revealed a homogeneous distribution of curcumin in TA-PBI gels. The thermal analysis confirmed the presence of curcumin in an amorphous form within the cold-set gel. PBI gels could effectively inhibit curcumin's immediate release in a simulated gastric medium (22.6% after 2 h) and led to its sustained release in a simulated intestinal condition (61.68% after 4 h). Release test results were aligned with the protein digestibility pattern. Peppas model could predict the release of curcumin from hydrogel in the gastrointestinal tract. In conclusion, TA-PBI gels can be introduced as promising delivery vehicles for the sustained release of curcumin in food and pharmaceutical systems.

Combinations of Legume Protein Hydrolysates Synergistically Inhibit Biological Markers Associated with Adipogenesis.

The objective was to investigate the anti-adipogenesis potential of selected legume protein hydrolysates (LPH) and combinations using biochemical assays and in silico predictions. Black bean, green pea, chickpea, lentil and fava bean protein isolates were hydrolyzed using alcalase (A) or pepsin/pancreatin (PP). The degree of hydrolysis ranged from 15.5% to 35.5% for A-LPH and PP-LPH, respectively. Antioxidant capacities ranged for ABTS•+ IC50 from 0.3 to 0.9 Trolox equivalents (TE) mg/mL, DPPH• IC50 from 0.7 to 13.5 TE mg/mL and nitric oxide (NO) inhibition IC50 from 0.3 to 1.3 mg/mL. LPH from PP–green pea, A–green pea and A–black bean inhibited pancreatic lipase (PL) (IC50 = 0.9 mg/mL, 2.2 mg/mL and 1.2 mg/mL, respectively) (p < 0.05). For HMG-CoA reductase (HMGR) inhibition, the LPH from A–chickpea (0.15 mg/mL), PP–lentil (1.2 mg/mL), A–green pea (1.4 mg/mL) and PP–green pea (1.5 mg/mL) were potent inhibitors. Combinations of PP–green pea + A–black bean (IC50 = 0.4 mg/mL), A–green pea + PP–green pea (IC50 = 0.9 mg/mL) and A–black bean + A–green pea (IC50 = 0.6 mg/mL) presented synergistic effects to inhibit PL. A–chickpea + PP–lentil (IC50 = 0.8 mg/mL) and PP–lentil + A–green pea (IC50 = 1.3 mg/mL) interacted additively to inhibit HMGR and synergistically in the combination of A–chickpea + PP–black bean (IC50 = 1.3 mg/mL) to block HMGR. Peptides FEDGLV and PYGVPVGVR inhibited PL and HMGR in silico, showing predicted binding energy interactions of −7.6 and −8.8 kcal/mol, respectively. Combinations of LPH from different legume protein sources could increase synergistically their anti-adipogenic potential.

Structural and rheological changes of texturized mung bean protein induced by feed moisture during extrusion

Mung bean protein isolate was texturized at different feed moisture contents (30.0, 49.3, and 60.0%) at a constant temperature (144.57 °C) to evaluate the changes in protein profile, solubility, thermal, structural (at secondary and tertiary levels) and rheological properties. SDS-PAGE, surface hydrophobicity, circular dichroism, FTIR spectroscopy, and fluorescence analyses revealed protein unfolding, aggregation, and structural rearrangement as a function of feed moisture content. Extrusion at 49.3% feed moisture produced texturized mung bean protein (TMBP) with favourable partial denaturation, the formation of small aggregates, improved solubility, and digestibility with strong gel forming behaviour, whereas 30.0 and 60.0% moisture content resulted in complete protein denaturation, the undesirable formation of large aggregates and weak gels. In conclusion, protein denaturation and formation of aggregates can be controlled by manipulating feed moisture content during extrusion, with 49.3% feed moisture prompting favourable partial denaturation to produce TMBP with desirable qualities for use as a vegetarian-based meat extender.

The effect of heat and transglutaminase treatment on emulsifying and gelling properties of faba bean protein isolate

The effects of heat treatment (90 °C, 5 or 30 min) and enzymatic crosslinking with transglutaminase (TG, 10, 100 or 1000 nkat/g protein) on emulsifying and gelling properties of faba bean protein isolate (FPI) were studied. Heat treatment of FPI caused a clear shift in far-UV CD spectra towards random coil structure and an increase in surface hydrophobicity from 181 to 504 RFU. TG crosslinked heat-treated FPI more efficiently as compared to native FPI. TG-induced crosslinking caused a reduction of surface hydrophobicity from 504 to 435 RFU. Emulsifying activity and stability indexes of FPI stabilized emulsions ranged between 25 and 30 m2/g and 18–35 min, respectively. Rheological properties of the FPI gels induced by heating, followed by acidification or TG treatment (10 or 100 nkat/g protein) were analyzed. FPI showed gel-like characteristics at 10% concentration (G′ = 180 Pa). When the heat-treated FPI dispersion was further acidified or TG-treated (100 nkat/g), G′ values of >6500 and > 3500 Pa were achieved, respectively. Water holding capacity of the FPI gels were >93% and >98% for acid- and TG-induced gels, respectively. The gel microstructures showed mainly heterogeneously-sized protein aggregates, however, no differences were observed between acid- and TG-induced gels.

Physicochemical characterization of protein isolates of amaranth and common bean and a study of their compatibility with xanthan gum

Vegetables are considered to be a sustainable source of promising biomaterials such as proteins and polysaccharides. In this study, four protein isolates (amaranth protein isolate API, amaranth globulin-rich protein isolate AGR, bean protein isolate BPI, and bean phaseolin-rich protein isolate BPR) were structurally characterized under different pH conditions (2–12) and their compatibility behavior with xanthan gum (XG) in aqueous medium was described. All protein isolates showed β turn and β sheet (78.24–81.11%), as the major secondary structures without statistically significant difference under the pH conditions surveyed. Protein isolates show solubility at pH ≤ 3 (40.4–85.1%) and pH ≥ 8 (57.6–99.9%) and surface hydrophobicity results suggest protein denaturation at pH ≤ 3. In the compatibility study, API/XG ratios between 1:1 and 5:1 at pH from 7 to 9 and the BPI/XG ratios from 1:1 to 20:1 at pH 7 form gels that do not require heating nor crosslinking agent addition. Zeta potential results, on the other hand, evidenced that formation of gels is driven by attractive electrostatic interaction of the charged regions of both biopolymers and intermolecular interactions such as hydrogen bonds.

Comparison of Bioactive Compounds Content and Techno-Functional Properties of Pea and Bean Flours and their Protein Isolates.

Recently, legume protein isolates are increasingly of interest as ingredients for the food industry; however, in spite of their health benefits, there is a limited information about the presence of bioactive compounds in the protein isolates. The objective of this study was to establish the phytochemical composition and selected techno-functional properties of pea and bean flours and their protein isolates obtained applying different drying methods. Regarding proximate composition, bean flour contained higher amounts of total protein (23%) and fat (44%) than pea flour; bean protein isolate (BPI) contained higher total and soluble protein, fat and starch than the pea protein isolate (PPI). Both protein isolates showed a similar emulsifying capacity (around 27%). Emulsion stability and foaming capacity were higher in the PPI (around 36%). Bean flour contained lower amounts of α-galactosides (31.64mg/g) but a higher trypsin inhibitors content (21.95 TIU/mg) than pea flour. The preparation procedure of the protein isolates affected the bioactive compound content. The PPI showed a reduction of inositol phosphates (13%), galactosides (76%), trypsin inhibitors (90%) and total phenolic compounds (35%) compared to its whole flour. The BPI contained higher amounts of inositol phosphates (137%) and total phenolic compounds (135%) than its flour, while it showed a lower content of galactosides (54%) and a similar amount of trypsin inhibitors. Thus, the bioactive compound content and the functional properties studied indicate that protein isolates can be used as ingredients with added-value in the development of new formulated food products, allowing their increasing use in the food industry.

Effects of drying techniques on the physicochemical, functional, thermal, structural and rheological properties of mung bean (Vigna radiata) protein isolate powder

Mung bean is an inexpensive yet sustainable protein source. Current work compared the effects of freeze (FD), spray (SD) and oven drying (OD), on mung bean protein isolate (MBPI) produced on pilot scale. All samples showed no dissociation of protein subunits and were thermally stable (Td = 157.90–158.07 °C). According to morphological studies, FD formed a porous protein while SD and OD formed wrinkled and compact crystals, respectively. FD and SD formed elastic gels with better gelling capacity than OD (aggregated gel). FD showed exceptional protein solubility, water and oil absorption capacity (4.23 g/g and 8.38 g/g, respectively). SD demonstrated the smallest particle size, excellent emulsion activity index (29.21 m2/g) and stability (351.90 min) and the highest β-sheet amount (37.61%). FTIR spectra for all samples showed characteristic peaks which corresponded well to the secondary structure of legume proteins. Rheological analysis revealed that gelation temperature for all MBPI lied around 90 °C. Current work described the different final properties achieved for MBPI produced under different drying techniques that allowed tailoring for different food systems, whereby FD is ideal for meat extender, SD is suitable for meat emulsion while OD is suitable in general protein-based application.

Recombinant neutral protease rNpI as fish feed additive to improve protein digestion and growth

The addition of heavy protein to aquafeed causes low digestibility, high cost and significant nitrogen pollution in the water. The addition of protease is an effective way of improving protein absorption, but few proteases have been developed specifically for aquafeeds. The hydrolysis efficiency of protease additives for plant protein in the neutral gut environment and their synergy with endogenous proteases has not been sufficiently investigated. In this study, the performance of the recombinant neutral protease rNpI as an aquafeed additive to reduce the raw protein materials in the diet of Carassius carassius during 56 days of growth was evaluated. rNpI effectively hydrolysed soya bean protein isolates (SPI) with a high degree of hydrolysation and a high small-peptide yield. The rNpI-treated SPI exhibited a notable antioxidant activity, which benefited fish health. In vitro digestibility indicated that rNpI complemented trypsin in SPI digestion better than papain or Alcalase. The growth trial showed that the addition of rNpI could warrant a reduction in the crude protein and gross energy of feed while producing a lower feed-conversion rate (FCR) and better growth performance. Crucian that were fed an RM-wheat-E diet (5.5% rapeseed meal and 5% wheat reduction) showed the best performance, with the lowest FCR and highest weight gain. These results indicate that rNpI could be an effective additive for the aquafeed industry and could provide economic benefits by reducing aquafeed protein requirements and nitrogen emissions. This study provides novel information and strategies for additive protease use and development in aquafeed.

Consequences of heating under alkaline pH alone or in the presence of maltodextrin on solubility, emulsifying and foaming properties of faba bean protein

Faba bean (Vicia faba L.) has attracted interest as a source of plant proteins due to the high protein content, easy cultivation, and the excellent nitrogen-fixing capacity. However, application of faba bean protein is still negligible in food products primarily due to its low solubility and functionality. In the current study, impact of heating under alkaline pH (11.0) alone or in the presence of maltodextrin on physicochemical characteristics, solubility, emulsifying activity, and foaming properties of faba bean protein isolate powder (FBP) from a pilot processing was investigated. Heating at alkaline pH irreversibly disrupted the original large micron-sized aggregates in untreated FBP, along with formation of the smaller aggregates with higher surface hydrophobicity. In the presence of maltodextrin, a FBP-maltodextrin conjugate with high degree of glycation was formed by the heating at alkaline pH. The heating under alkaline pH either in the presence and absence of maltodextrin significantly improved the protein solubility from 43, 14, and 35% at pH 3.0, 6.0, and 7.0, respectively to more than 90%. Compared to the untreated FBP, the FBP-maltodextrin sample heated at pH 11.0 could produce emulsions that were stable against flocculation and phase separation for 15 days storage at pH 6–7 or in the presence of salt. Moreover, foaming capacity and stability of the FBP and FBP-maltodextrin samples heated at pH 11.0 was greatly improved. This study suggested that heating under alkaline pH has a great potential to improve the functional properties of FBP to enable its wide applications in food area.

Physicochemical and pH-dependent functional properties of proteins isolated from eight traditional Chinese beans

Mung bean (MPI), black bean (BPI), adzuki bean (API), rice bean (RPI), black kidney bean (BKPI), speckled kidney bean (SKPI), chickpea (CPI) and cowpea (CPPI) protein isolates were assessed for their surface (charge, hydrophobicity: H0 and tension) and functional properties (solubility, water/oil holding capacity, WHC/OHC; foaming capacity/stability, FC/FS; emulsifying activity/stability indices, EAI/ESI and least gelling capacity, LGC) at pH 3.0, 5.0, 7.0 and 9.0, using soybean (SPI) and pea (PPI) protein isolates as controls. Physicochemical properties of these proteins, e.g., amino acid composition and colour (L*, a* &b*, WI: whiteness index), were also characterized. API, RPI, BKPI, SKPI and CCPI exhibited a better amino acid profile and protein digestibility than other isolates. BKPI (27.01) and SKPI (20.48) showed higher WI, while CPI (−21.92) was the lowest. For all isolates, H0 was the highest at pH 3.0, followed by pH 7.0 and 9.0, while surface tension was the highest at pH 5.0, followed by pH 3.0. Compared to other proteins, BKPI and SKPI showed lower solubility, but were more effective to reduce surface tension. Most of the traditional legume proteins had similar EAI. CCPI showed better WHC/OHC and API, RPI, BKPI and SKPI displayed excellent FC/FS. Interestingly, LGCs of MPI (8%), BKPI (4%), SKPI (4%) and CCPI (6%) at pH 3.0 were significantly lower than other isolates (12%). Overall, BKPI and SKPI have good nutritional profiles and also possess excellent functionalities (except for WHC/OHC), which are very promising as new alternative legume proteins to SPI and PPI.

Dark red kidney bean (Phaseolus vulgaris L.) protein hydrolysates inhibit the growth of oxidizing substances in plain yogurt

Protein isolate was obtained from dark red kidney bean ( Phaseolus vulgaris , L). The isolate had 86.4% protein and the protein was subjected to enzymatic hydrolysis by pepsin. Enzymatic hydrolysis resulted in a significant ( p < 0.05) increase in total polyphenol content (TPC) in the hydrolysates which was 44.8 ± 1.31 mg GAE/gm. The DPPH radical scavenging activity was also significantly ( p < 0.05) increased in protein hydrolysates than that of the protein isolate with an IC 50 value of 0.002 ± 0.00001 mg/mL. Therefore, the hydrolysates exhibited stronger antioxidant activity than the protein isolate. Moreover, the antioxidant activity of the hydrolysates was higher than ascorbic acid (AA), which is commercially used in the food industry. Besides, owing to antioxidant property, red kidney bean protein hydrolysates were able to suppress the growth of oxidizing substances in yogurt at an application rate of 3 gm/L during storage at room temperature for three (3) days. Protein hydrolysates retarded the formation of oxidizing substances by 45.8% compared to control. Notably, hydrolysis using pepsin improved the ability of red kidney bean protein isolate to inhibit the formation of oxidizing substances. • Hydrolysis of protein isolates resulted in an increase of total polyphenol content. • Hydrolysates had a higher antioxidant activity than that of the protein isolates. • Hydrolysates exhibited stronger antioxidant activity as compared to ascorbic acid. • Reduced growth of oxidizing substances in yogurt by the application of hydrolysates. • Red kidney bean protein hydrolysates can be used as antioxidants in foods.

Protein quality of dehulled-defatted African mesquite bean (Prosopis africana) flour and protein isolates

In this study, the protein quality of dehulled-defatted African mesquite bean (Prosopis africana) flour and protein isolates obtained using micellization and isoelectric precipitation methods were investigated. The dominant amino acids in the dehulled-defatted Prosopis africana flour and protein isolates included aspartic acid, glutamic acid, leucine and arginine, while the first, second and third limiting amino acids were methionine, threonine and valine/tryptophan, respectively. Amino acid profiles and scores, classifications and ratios, predicted protein efficiency ratios (1.79–2.89), biological (12.61–37.97%) and net protein (15.77–50.84%) values, essential amino acid (63.94–87.02%) and nutritional (23.33–70.78%) indexes showed that the dehulled-defatted P. africana flour and its protein isolates were of high protein quality and could be employed in complementing cereal-based and other similar foods whose proteins are deficient in lysine. Isoelectric precipitation method yielded protein with better nutritional quality compared to the micellization method. P. africana flour and protein isolates could therefore be exploited as protein sources in food formulation for tackling protein malnutrition in Africa.