Higher Surface Hydrophobicity Research Articles

Influence of sodium chloride and sodium pyrophosphate on the physicochemical and gelling properties of silver carp myofibrillar proteins sol subjected to freeze-thaw cycles

The effects of different content of sodium chloride (NaCl) and sodium pyrophosphate (SPP) on the stability of myofibrillar proteins (MPs) sol subjected to freeze-thaw cycles (F-T cycles), as well as the performance of heat-induced gel subsequently formed from the frozen-thawed MPs sol, were investigated. The molecular states of MPs with high NaCl (15 g/kg, 25 g/kg) and additional SPP (1 g/kg, 3 g/kg, 5 g/kg) were altered due to the cross-linking and aggregation, showing the larger turbidity, higher surface hydrophobicity, and intrinsic fluorescence intensity. Additionally, compared with the control and 5 g/kg NaCl groups, MPs sol with high NaCl content exhibited less proteins denaturation and higher stability of water molecules after 2 F-T cycles. However, the poor gel properties were observed in high NaCl groups with larger cooking loss, weak gel strength, inferior textural parameters, and disorganized micro-network structure, revealing cross-linking and aggregation of MPs during F-T cycles were negative to the gelling properties. Furthermore, the additional SPP (1 g/kg) significantly inhibited protein aggregation and water migration during F-T cycles of MPs sol, resulting in superior gel properties with ordered gel microstructures.

Molecular structural modification of β-conglycinin using pH-shifting with ultrasound to improve emulsifying properties and stability

This present work underlines the effect of pH-shifting at pH 2 and pH 12 individually or combined with ultrasound treatment to modify the molecular structure of β-conglycinin (7S) on its emulsifying properties and stability. Fourier transform infrared (FTIR) spectroscopy and intrinsic fluorescence spectroscopy showed that pH-shifting improves the molecular structure of 7S, while ultrasound further promotes structural changes. In particular, the pH-shifting at pH 12 combined with ultrasound treatment (U-7S-12) resulted in more significant changes than the pH-shifting at pH 2 combined with ultrasound (U-7S-2). U-7S-12 showed a significant reduction in protein particle size from 152 to 34.77 nm and a relatively smooth protein surface compared to 7S. The protein had the highest surface hydrophobicity and flexibility at 81,560.0 and 0.45, respectively, and the free sulfhydryl content from 1.57 to 2.02 μmol/g. In addition, we characterized the emulsions prepared after 7S treatment. The single or combined treatment increased the interfacial protein adsorption of the samples, which showed lower viscosity and shear stress compared to 7S. The U-7S-12 emulsion exhibited the highest emulsifying properties and was more stable than other emulsions under creaming, heating, and freeze–thaw conditions. In summary, the concerted action of pH-shifting and ultrasound can modify the structure, and combined alkaline pH-shifting and ultrasound treatment can further improve the emulsifying properties and stability of 7S.

Structural modification induced by heat treatments improves the emulsifying attributes of lacquer seed protein isolate

The lacquer seed oil has received extensive attention in the food industry due to its health function, such as regulating blood lipids. But its by-product, lacquer seed meal, is often used as a low-value-added product such as animal feed. Lacquer seed meal contains about 20 % protein, which has amphiphilic properties, and there is limited attention to its emulsifying properties. In this study, the impact of heat treatment on the emulsifying properties of lacquer seed protein isolate (LSPI) was investigated. The EAI and ESI of the 120 °C heated LSPI increased by 77.1 % and 55.2 %, respectively. The emulsions prepared using heat-modified LSPI (120 °C) further showed lower hydroperoxide, TBARS and protein carbonyl contents (only 61.3 %, 61.0 % and 58.6 % of control) after storage. This result indicates that heat-treated LSPI retarded lipid and protein oxidation in LSPI-stabilized emulsions during storage. Changes in protein structure showed that increasing heating temperature resulted in the depolymerization of tertiary structure, higher surface hydrophobicity and lower contents of α-helix of LSPI. These changes in protein structure made the heated LSPIs have better emulsifying properties. Therefore, these findings developed a new use of LSPI and greatly enhanced the potential of LSPI as a natural emulsifier in the food industry.

Physicochemical and functional properties of Pleurotus geesteranus proteins

Edible mushroom protein has been regarded as a promising protein source due to its nutritional value and sustainability. In the present study, Pleurotus geesteranus proteins were extracted with alkaline solution and then precipitated with salting out (PPS) and isoelectric point precipitation (PPI), respectively. The influences of precipitation method on the physicochemical and functional properties of these two kinds of proteins were studied. The results showed that both PPS and PPI had a good balance of essential amino acids. These two proteins were mainly consisted of polypeptides with a molecular weight lower than 70 kDa. Using proteome analysis, a number of 772 and 459 protein compositions were identified in PPS and PPI, respectively. Compared to PPS, PPI showed a higher zeta potential, higher surface hydrophobicity, lower content of β-sheet and β-turn secondary structure, as well as lower denaturation temperature (Td) and enthalpy change of the denaturation (ΔH). These differences in the physicochemical properties between PPS and PPI resulted in the occurrence of differences in their functional and digestive properties. For example, PPS showed obviously higher protein solubility in water than PPI, especially at natural pH, PPS solution was clear, while PPI showed precipitates. PPI had higher foam capability (FC), lower foaming stability (FS), and lower emulsion stability index (ESI) as compared to PPS. PPI was easier to digest in the pepsin digestion period, while PPS showed a higher nitrogen release after trypsin digestion. These findings on the physicochemical and functional properties of P. geesteranus proteins will help to broaden their applications as protein ingredient in food industry.

Erosion Resistant Hydrophobic Coatings for Passive Ice Protection of Aircraft

Novel polymeric coatings, namely slippery polyurethane (SPU) coatings, with high surface hydrophobicity and superior erosion resistance against high speed solid particles and water droplets were successfully developed to protect the leading edge of fast moving aerodynamic structures, such as aircraft wings and rotor blades, against ice accretion. The coatings comprise newly synthesized surface-modifying polymers (SMPs) bearing fluorinated and polydimethylsiloxane branches at a loading level of 1–5 wt.%, based on the total resin solid, which showed good compatibility with the erosion-resistant polyurethane matrix (PU-R) and rendered effective surface hydrophobicity and slipperiness to the coatings, as evidenced by the high water contact angles of 100–115°. The coatings can be easily be sprayed or solution cast and cured at ambient temperature to provide highly durable thin coating films. X-ray photoelectron spectroscopy (XPS) investigation showed concentration of fluorine on the surface. The presence of 1–5 wt.% of SMPs in the polyurethane matrix slightly reduced the tensile modulus but had no significant impact on the tensile strength. All coating films exhibited good thermal stability with no material softening or degradation after heating at 121 °C for 24 h. DSC heating scans revealed no thermal transitions in the temperature range of −80 °C to 200 °C. Ice adhesion strength (IAS) tests using a static push rig in a cold room of −14 °C showed IAS as low as 220 kPa for the SPU coatings, which is much lower than that of PU-R (i.e., about 620 kPa). Sand erosion tests using 50 μm angular alumina particles at an impinging speed of 150 m/s and an impinging angle of 30° revealed very low erosion rates of ca. 100 μg/g sand for the coatings. Water droplet erosion tests at 175 m/s using 463 μm droplets with 42,000 impingements every minute showed no significant coating removal after 20 min of testing. The combination of the high surface hydrophobicity, low ice adhesion strength and superior erosion resistance makes the SPU coatings attractive for ice protection of aircraft structures, where the coatings’ erosion durability is of paramount importance.

Amyloid fibrils act as a reservoir of soluble oligomers, the main culprits in protein deposition diseases.

Amyloid fibril formation plays a central role in the pathogenesis of a number of neurodegenerative diseases, including Alzheimer and Parkinson diseases. Transient prefibrillar oligomers forming during the aggregation process, exhibiting a small size and a large hydrophobic surface, can aberrantly interact with a number of molecular targets on neurons, including the lipid bilayer of plasma membranes, resulting in a fatal outcome for the cells. By contrast, the mature fibrils, despite presenting generally a high hydrophobic surface, are endowed with a low diffusion rate and poorly penetrate the interior of the lipid bilayer. However, increasing evidence shows that both intracellular α-synuclein fibrils, as well and as extracellular amyloid-β and β2-microglobulin fibrils, can release oligomers over time that quickly diffuse to reach the membrane of the neighboring cells. The persistent leakage of harmful oligomers from fibrils triggers an ongoing cascade of events resulting in a sustained injury to neurons and glia and also provides aggregates with the ability to cross biological membranes and diffuse between cells or cellular compartments.

Carbonate Lake Sediments in the Plastics Processing-Preliminary Polylactide Composite Case Study: Mechanical and Structural Properties.

In this study, the influence of carbonate lake sediments (Polylactide/Carbonate Lake Sediments–PLA/CLS) on the mechanical and structural properties of polylactide matrix composites was investigated. Two fractions of sediments originating from 3–8 and 8–12 m were analysed for differences in particle size by distribution (Dynamic Light Scattering–DLS), phase composition (X-ray Diffraction–XRD), the presence of surface functional groups (Fourier Transform-Infrared–FT-IR), and thermal stability (Thermogravimetric Analysis–TGA). Microscopic observations of the composite fractures were also performed. The effect of the precipitate fraction on the mechanical properties of the composites before and after conditioning in the weathering chamber was verified through peel strength, flexural strength, and impact strength tests. A melt flow rate study was performed to evaluate the effect of sediment on the processing properties of the PLA/CLS composite. Hydrophobic-hydrophilic properties were also investigated, and fracture analysis was performed by optical and electron microscopy. The addition of carbon lake sediments to PLA allows for the obtention of composites resistant to environmental factors such as elevated temperature or humidity. Moreover, PLA/CLS composites show a higher flow rate and higher surface hydrophobicity in comparison with unmodified PLA.

Green synthesis of a hydrophobic metal-organic gel for the capture of trace odorous hexanal from humid air

The development of superhydrophobic adsorbents for the capture of trace volatile organic compounds (VOCs) from humid indoor air is still a challenge. Herein, we reported the formation of a granular zinc-based metal-organic gel, i.e., ZIF-412(gel) by optimizing the synthesis conditions. The thermally stable xerogel exhibited high surface area (1008 m2/g), hydrophobicity, and viscosity for self-depositing on the substrate such as non-woven fibers. Dynamic adsorption experiments under various humidity conditions demonstrated as-synthesized ZIF-412(gel) owned excellent VOC (hexanal) adsorption performance with adsorption capacity higher than commercial activated carbon and some water-stable MOFs including ZIF-8, ZIF-67, MIL-101(Cr) and ZIF-414. ZIF-412(gel) could be regenerated at temperature as low as 358 K without obvious loss in adsorption capacity. The adsorption mechanism of hexanal over ZIF-412(gel) is also simulated by Grand canonical Monte Carlo (GCMC).

Effect of ultrasound on pH-shift to improve thermal stability of coconut milk by modifying physicochemical properties of coconut milk protein

In this study, ultrasound was subjected to pH-shift treatment to explore their synergistic effects on thermal stability of coconut milk and the underlying mechanism was explored by investigating the changes in functional properties and structures of coconut milk protein. The results showed that ultrasound combined with alkaline pH-shift treatment improved the viscosity (from 239.5 to 309.2 mPa), increased zeta potential (from −22.3 to −24.8 mV) and decreased the size distribution curve right shift distance (from 4.07 to 2.15 μm) of coconut milk compared to alkaline pH-shift treatment alone. This was future elucidated by the enhance effect of ultrasound assisted alkaline pH-shift to improve physicochemical properties of coconut milk protein, including higher solubility (from 43.4% to 51.8%), higher surface hydrophobicity (from 5877.2 to 13372.7) and fewer free sulfhydryl group (from 441.8 to 352.5 μmol/g). The improved properties were consistent with changes in the secondary structure, tertiary structure and microscopic state of coconut globin reflected by the fourier transform infrared spectroscopy, fluorescence spectroscopy and scanning electron microscopy, respectively. In conclusion, ultrasound can amplify the effect of pH-shift on increasing the thermal stability of coconut milk by modifying functional properties and structures of coconut milk protein, especially under alkaline pH-shift treatment.

Soy proteins as vehicles for enhanced bioaccessibility and cholesterol-lowering activity of phytosterols.

The formulation of phytosterol (PS)-enriched functional foods has attracted increasing interest in the recent years, owing to its potential health effects. However, the poor solubility and bioavailability greatly limit PS application in this regard. This study investigated whether soy protein isolate (SPI) could effectively perform as a nanocarrier for improving the water solubility, bioaccessibility, and cholesterol-lowering activity of PSs. In this work, we fabricated SPI-PS nanocomplexes, which not only can enhance the stability and bioaccessibility of PS, but also improve the cholesterol-lowering ability of SPI. This improvement was mainly due to the formation of protein-active substance complexes, through hydrophobic interactions. The complexation with PSs resulted in formation of nanosized particles with greater sizes, lower ζ-potential, and higher surface hydrophobicity. The encapsulation efficiency, loading amount, and solubility of PS were closely related to the applied PS concentration in the mixed dispersions, and the maximal PS solubility in the aqueous phase reached about 1.63 mg mL-1 at the highest PS concentration (2.0mg mL-1 ). The PS molecules in the nanocomplexes were mainly present in the amorphous form. The enhanced in vitro cholesterol-lowering activity of PS nanocomplexes relative to free PS seemed to be closely related to its higher bioaccessibility. The findings are of relevance for the development of food-grade PS ingredients suitable for the formulations of PS-enriched functional foods. © 2022 Society of Chemical Industry.

Ordered Ag Nanoneedle Arrays with Enhanced Electrocatalytic CO2 Reduction via Structure-Induced Inhibition of Hydrogen Evolution.

Silver is an attractive catalyst for converting CO2 into CO. However, the high CO2 activation barrier and the hydrogen evolution side reaction seriously limit its practical application and industrial perspective. Here, an ordered Ag nanoneedle array (Ag-NNAs) was prepared by template-assisted vacuum thermal-evaporation for CO2 electroreduction into CO. The nanoneedle array structure induces a strong local electric field at the tips, which not only reduces the activation barrier for CO2 electroreduction but also increases the energy barrier for the hydrogen evolution reaction (HER). Moreover, the array structure endows a high surface hydrophobicity, which can regulate the adsorption of water molecules at the interface and thus dynamically inhibit the competitive HER. As a result, the optimal Ag-NNAs exhibits 91.4% Faradaic efficiency (FE) of CO for over 700 min at -1.0 V vs RHE. This work provides a new concept for the application of nanoneedle array structures in electrocatalytic CO2 reduction reactions.

Electrochemical cleaning of superhydrophobic polyvinylidene fluoride/polymethyl methacrylate/carbon black membrane after membrane distillation

In membrane distillation, separation can be greatly enhanced by the use of membranes with high porosity and hydrophobic surface. However, their separation performance drops significantly due to wetting in the presence of surfactant. In this work, polymethyl methacrylate (PMMA), carbon black and/or conductive ink was incorporated into PVDF membranes with microroughness templated from weave pattern to improve membrane morphology electrochemical properties. Fourier transform infrared spectra showed characteristic peaks of PVDF and additives. Carbon black and conductive ink caused the formation of secondary roughness, while PMMA induced high porosity and thickness. The PVDF-PMMA-CB membrane with a superhydrophobic surface also attained electrical conductivity with cyclic voltammetry recorded. A high permeate flux and stable salt rejection were achieved using this membrane in membrane distillation. It could also be electrochemically cleaned within 4 min after wetting by surfactant, showing a recovered water contact angle of 148.8 °. The membrane could be cleaned by hypochlorite (OCl−), hypochlorous acid (HOCl), and/or ferric hydroxides generated during electrochemical cleaning. The cleaned PVDF-PMMA-CB membrane achieved NaCl rejection of more than 95%, but a slightly lower permeate flux than the permeate flux before wetting.

Fabrication of PEBA/HZIF-8 Pervaporation Membranes for High Efficiency Phenol Recovery.

Phenol and its chemical derivatives serve as essential chemical materials are indispensable for the synthesis of many kinds of polymers. However, they are highly toxic, carcinogenic, difficult to be degraded biologically, and often found in aqueous effluents. Recovery of hazardous phenol from wastewater remains a daunting challenge. Herein, we prepared a hybrid membrane containing polyether block amide (PEBA) matrix and HZIF-8 fillers. To improve the compatibility between ZIF-8 and PEBA, ZIF-8 was modified by using polystyrene (PS) as a template to prepare porous HZIF-8. ZIF-8, composed of zinc nodes linked by the imidazole ring skeleton, is a kind of inorganic material with high hydrothermal stability, ordered pores, and hydrophobic microporous surfaces, which has a wide range of applications in membrane separation. The separation performance of the PEBA/HZIF-8 based membranes for phenol/water is improved due to the presence of PS on the surface of HZIF-8 and the imidazole ring skeleton in ZIF-8, which enhance the π–π interaction between HZIF-8 and phenol molecules. The effects of HZIF-8 content, feed phenol concentration, and feed temperature on the pervaporation performance of PEBA/HZIF-8 membranes were further investigated. The results showed that the pervaporation performance of the PEBA/HZIF-8-10 membrane was promising with a separation factor of 80.89 and permeate flux of 247.70 g/m2·h under the feed phenol concentration of 0.2 wt % at 80 °C. In addition, the PEBA/HZIF-8-10 membrane presented excellent stability, which has great prospect for practical application in phenol recovery from waste water.

Anti-Fouling Performance of Hydrophobic Hydrogels with Unique Surface Hydrophobicity and Nanoarchitectonics.

Hydrogel is a kind of soft and wet matter, which demonstrates favorable fouling resistance owing to the hydration anti-adhesive surfaces. Different from conventional hydrogels constructed by hydrophilic or amphiphilic polymers, the recently invented “hydrophobic hydrogels” composed of hydrophobic polymers exhibit many unique properties, e.g., surface hydrophobicity and high water content, suggesting promising applications in anti-fouling. In this paper, a series of hydrophobic hydrogels were prepared with different chemical structures and water content for anti-fouling investigations. The hydrophobic hydrogels showed high static water contact angles (WCAs > 90°), indicating remarkable surface hydrophobicity, which is abnormal for conventional hydrogels. Compared with the conventional hydrogels, all the hydrophobic hydrogels exhibited less than 4% E. coli biofilm coverage, showing a contrary trend of anti-fouling ability to the water content inside the polymer. Typically, the poly(2-(2-ethoxyethoxy)ethyl acrylate) (PCBA) and poly(tetrahydrofurfuryl acrylate) (PTHFA) hydrogels with relatively high surface hydrophobicity showed as low as 5.1% and 2.4% E. coli biofilm coverage even after incubation for 7 days in bacteria suspension, which are about 0.32 and 0.15 times of that on the hydrophilic poly(N,N-dimethylacrylamide) (PDMA) hydrogels, respectively. Moreover, the hydrophobic hydrogels exhibited a similar anti-adhesion ability and trend to algae S. platensis. Based on the results, the surface hydrophobicity mainly contributes to the excellent anti-fouling ability of hydrophobic hydrogels. In the meantime, the too-high water content may be somehow detrimental to anti-fouling performance.

Polystyrene Macroporous Magnetic Nanocomposites Synthesized through Deep Eutectic Solvent-in-Oil High Internal Phase Emulsions and Fe3O4 Nanoparticles for Oil Sorption.

In this work, we report a nonaqueous one-step method to synthesize polystyrene macroporous magnetic nanocomposites through high internal phase emulsions (HIPEs) formulated with the deep eutectic solvent (DES) composed of urea:choline chloride (U:ChCl, in a 2:1 molar ratio) as the internal phase and co-stabilized with mixtures of Span 60 surfactant and non-functionalized magnetite nanoparticles (Fe3O4 NPs). The porous structure and the magnetic and lipophilic properties of the nanocomposite materials were easily tailored by varying the amount of Fe3O4 NPs (0, 2, 5 and 10 wt %) and the surfactant Span 60 (0, 5, 10, and 20 wt %) used in the precursor emulsion. The resultant nanocomposite polyHIPEs exhibit high sorption capacity toward different oils (hexane, gasoline, and vegetable oil) due to their high porosity, interconnectivity, and hydrophobic surface. It was observed that the oil sorption capacity was improved when the amount of surfactant decreased and Fe3O4 NPs increased in HIPE formulation. Therefore, polyHIPE formulated with 5 and 10 wt % Span 60 and Fe3O4 NPs, respectively, showed the highest oil sorption capacities of 4.151, 3.556, and 3.266 g g–1 for gasoline, hexane, and vegetable oil, respectively. In addition, the magnetic monoliths were reused for more than ten sorption/desorption cycles without losing their oil sorption capacity.

Comparative Study on the Characterization of Myofibrillar Proteins from Tilapia, Golden Pompano and Skipjack Tuna.

In this study, the physicochemical properties, functional properties and N-glycoproteome of tilapia myofibrillar protein (TMP), golden pompano myofibrillar protein (GPMP) and skipjack tuna myofibrillar protein (STMP) were assessed. The microstructures and protein compositions of the three MPs were similar. TMP and GPMP had higher solubility, sulfhydryl content and endogenous fluorescence intensity, lower surface hydrophobicity and β-sheet contents than STMP. The results showed that the protein structures of TMP and GPMP were more folded and stable. Due to its low solubility and high surface hydrophobicity, STMP had low emulsifying activity and high foaming activity. By N-glycoproteomics analysis, 23, 85 and 22 glycoproteins that contained 28, 129 and 35 N-glycosylation sites, were identified in TMP, GPMP and STMP, respectively. GPMP had more N-glycoproteins and N-glycosylation sites than STMP, which was possibly the reason for GPMP’s higher solubility and EAI. These results provide useful information for the effective utilization of various fish products.

Preparation and Properties of Polyimide Composite Membrane with High Transmittance and Surface Hydrophobicity for Lightweight Optical System.

Polyimide membranes have excellent physiochemical properties which make them valuable materials for optical area. However, common aromatic polyimide membrane trend to show low transmittance in visible region because of the charge-transfer complex (CTC) in molecular structures. Moreover, it’s trending to show high moisture uptakes because of the hydrophilic imide rings in molecular structure. In this work, a polyimide composite membrane with SiO2 antireflective membrane on both sides was prepared. High transmittance (93% within 500~800 nm) and surface hydrophobicity was realized simultaneously. The polyimide composite membrane showed great optical homogeneity. The SiO2 antireflective membranes on polyimide substrate were prepared through a simple and efficient sol-gel method. The surface roughness of polyimide membrane substrate on each side has been improved to 1.56 nm and 3.14 nm, respectively. Moreover, the excellent thermal stability and mechanical property of polyimide membrane has been preserved, which greatly improves the range of applications for the composite membrane. It is a good candidate for light weight optical system.

Impact of covalent grafting of two flavonols (kaemperol and quercetin) to caseinate on in vitro digestibility and emulsifying properties of the caseinate-flavonol grafts

Covalent grafting of one of the two flavonols (kaemperol and quercetin) to caseinate was achieved by a reaction between the heat-oxidized flavonols and caseinate at flavonol-lysine molar ratios of 1:100 and 1:200. Grafted caseinate products (GCPs) showed − NH2 content reduction and respective kaemperol and quercetin contents of 1.08–6.13 and 3.23–6.64 mmol/kg protein. Quercetin was more reactive than kaemperol under the same conditions, while long-time flavonol heat and higher flavonol-lysine molar ratio caused greater flavonol-grafting. GCPs subjected to 180-day storage had further flavonol-grafting, −NH2 content decrease, and weak protein crosslinking. GCPs consistently had higher surface hydrophobicity but lower emulsification and digestibility than caseinate, while greater flavonol-grafting caused a remarkable value change. Meanwhile, the Kjeldahl method was more suitable than the UV-absorption method to evaluate protein digestibility, because the grafted flavonols in this case did not interfere with data results. Collectively, the covalent flavonol-grafting of proteins can impact the assayed protein functionalities.

Super Liquid-repellent Surfaces and 3D Spheroids Growth.

Substrates composition and surface features of materials rule adhesion control of cells to surfaces. As a result, most of the aspects of cell functions, such as spreading, migration, proliferation, and differentiation, can be significantly influenced in biomedical applications. Cell cultures make possible to understand cell biology, tissue morphology, mechanisms of diseases, drug action, and tissue engineering development, among others. Recent techniques related to culturing 3D cell aggregates in the presence of very low wettable surfaces represent an innovative field for in vitro experimentation aimed at more reliable conditions to investigate both tumor and non-tumor cell lines. Matching in particular cell biology to innovative materials, this work reviews the recent literature available on promoting cell aggregates formation strongly influenced by the high surface hydrophobicity. In particular, for spheroid formation, the highest water repellent coatings seem to be required for the significant effectiveness of the process. In this way, 3D cell culture has become a reliable method for reproducing in vitro cellular growth in more realistic physiological conditions.

The effect of isolation techniques on the physicochemical properties of Moringa oleifera protein isolates

The effect of alkaline extraction/isoelectric precipitation and salt extraction/micellization on proximate composition, anti-nutritional content, amino acid composition and physicochemical properties of Moringa oleifera protein isolates were studied. Protein extractability was influenced by NaCl concentration, pH and temperature. The protein concentration of isoelectric and micellized isolates were 80% and 90%, respectively. Micellized isolates recorded higher yields (49%) than isoelectric isolates (15%). Both isolates were free of phytate, tannin, saponin and oxalate. Micellized isolates contained all essential amino acids except lysine and methionine which met the FAO/WHO recommendations for children; isoelectric isolates were deficient in methionine. Molecular weights of protein fractions were approximately 8.5–32.5 kDa. Micellization resulted in isolates with a lighter color, higher surface hydrophobicity (184) and higher transition enthalpy (109 J/g); isoelectric precipitation resulted in isolates with a higher denaturation temperature (190 °C). The results indicated that M. oleifera protein isolates could be a potential source of plant-based protein. The differences in physicochemical properties between the isolates indicate different functionalities and potentially different applications.