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The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Residual lipids (RL) in whey protein isolate (WPI) are detrimental to optimal functional applications (e.g., foaming and low turbidity) and contribute to off-flavor development during powder storage. The objective of this research was to prepare an experimental WPI by removing RL without using the traditional microfiltration process and compare its properties with commercially available WPI made using microfiltration and some other whey powders. We hypothesize that by adjusting the pH of whey to <5.0, we would be close to the isoelectric point of any remaining denatured proteins (DP) and phospholipoproteins (PLP), and therefore reduce electrostatic repulsion between these molecules. Furthermore, demineralization of the acidified whey protein solution by UF combined with diafiltration (DF) should reduce ionic hindrance to aggregation and thereby help with the aggregation of these DP as well as most RL; centrifugation or clarification could be used to remove these materials. Calcium should also be more extensively removed by this approach, which should improve the heat stability of the experimental WPI. Demineralization was achieved on a pilot scale by acidifying liquid (cheese) whey protein concentrate containing 34% protein (WPC-34) to pH 4.5 using HCl, and UF of the whey protein solution along with extensive DF using acidified (pH ∼3.5) reverse osmosis filtered water. Demineralized whey protein solution was adjusted to various combinations of pH (4.1–4.9), conductivities (500–2,000 μS/cm), and protein concentrations (1%–7%) and then centrifuged at 10,000 × g for 10 min. The effective sedimentation (precipitation) of RL in these treatments was estimated by measuring the turbidity of the supernatants. Maximum precipitation was observed at pH 4.5 to 4.7. Reducing conductivity via UF/DF increased the precipitation of RL due to reduced ionic hindrance to aggregation. Maximum sedimentation of RL was observed at protein concentrations ≤3% because of a higher density difference between the precipitate and serum phase. Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis confirmed the sedimentation of phospholipoproteins, caseins, and DP upon isoelectric precipitation at pH ∼4.5, while native whey proteins or undenatured whey proteins remained soluble in the supernatant, unaffected by the pretreatment. To scale up the process, 750 L of fluid WPC-34 was acidified and demineralized by UF (volume concentration factor = 1.35) and DF until the permeate solids reached 0.1% (when desired demineralization was achieved), clarified using a pilot-scale desludging clarifier to remove RL, neutralized, ultrafiltered to concentrate the protein, and then spray-dried to produce an experimental WPI (91% protein and 1.8% fat on a dry basis [db]). In another trial, demineralized UF concentrate was clarified by gravity sedimentation and the supernatant was neutralized, ultrafiltered, and spray-dried to produce a second experimental WPI (91% protein and <1% fat db). These experimental WPI powders were compared with several commercially available WPI powders to assess functional properties such as solubility, heat stability, foamability and foam strength, gelation, and sensory attributes over accelerated storage. Experimental WPI had excellent functional properties, had low turbidity, were highly heat stable, and only developed very slight-to-slight off-flavors upon accelerated storage, and their properties were comparable to the WPI manufactured commercially using microfiltration even after accelerated storage. [ABSTRACT FROM AUTHOR]

With the increasing world population and vegan diet, there has been increasing consumer demand for alternative protein sources. A substitute for animal proteins is the plant protein, for instance, leaves. The Pereskia aculeata, known as ora-pro-nóbis, is undoubtedly a leafy vegetable with great potential due to its relatively high protein content (17 to 28%). This study aimed to produce ora-pro-nóbis protein concentrate (OPNPC) from ora-pro-nóbis leaves flour (OPNF) by isoelectric precipitation at three different pH's (3.5, 4.0, and 4.5). The protein extraction by precipitation in different pHs produced OPNPC with protein content and extraction yield ranging from 52 to 55% and 1–4%, respectively. Given the highest yield, the concentrate obtained at pH 3.5 (OPNPC3.5) was selected for further investigation and comparison to OPNF. The differences in color, techno-functional properties, in vitro protein digestibility (IVPD), and structural properties were evaluated. Most techno-functional properties were statistically higher in OPNPC3.5 than in OPNF. These included its water solubility, oil holding capacity, foam capacity and stability, and emulsifying activity and stability. OPNPC3.5 had a higher IVPD (80%) than flour (77%). Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed distinct compositions of materials, which can explain the difference in techno-functional properties. The findings indicate controlling protein extraction conditions as a useful technique to maximize the yield of protein concentrate obtained from ora-pro-nóbis, which was more nutritious and had better techno-functional properties than flour. This demonstrates its potential as an alternative plant-based protein to design healthy and sustainable food products. [ABSTRACT FROM AUTHOR]

The aim of this study was to improve the yield of protein isolates obtained from sunflower oil cakes by means of sequential implementation of isoelectric precipitation and ultrafiltration. The proteins were extracted from sunflower oil cake in mild acidic conditions (pH = 6 with solution of NaCl with concentration of 0.5, 1 and 2M). The first fraction of protein isolate was obtained by means of isoelectric precipitation at pH = 4, 3.5 and 3. Total protein, ash and dry matter contents, and residual chlorides of raw material and precipitates were determined. The second fraction was obtained from supernatant taken from the highest yield precipitate by means of ultrafiltration. The ultrafiltration experiments were conducted with an UF10-PAN membrane at a transmembrane pressure of 0.2, 0.35 and 0.5 MPa, and a volume reduction ratio (VRR) of 2, 3, 4, and 5. Total protein, ash, and dry matter contents of retentates and permeate were determined. [ABSTRACT FROM AUTHOR]

ABSTRACT: Residual lipids (RL) in whey protein isolate (WPI) are detrimental to optimal functional applications (e.g., foaming and low turbidity) and contribute to off-flavor development during powder storage. The objective of this research was to prepare an experimental WPI by removing RL without using the traditional microfiltration process and compare its properties with commercially available WPI made using microfiltration and some other whey powders. We hypothesize that by adjusting the pH of whey to

Plant-based proteins are increasingly being utilized as they are sustainable, economical, and can enhance the organoleptic properties of food products. This study investigated the effect of extraction and isolation techniques (alkaline extraction & isoelectric precipitation and salt extraction & micellization) on the functional properties ((solubility, water holding and oil absorption capacity (WHC/OAC), emulsifying activity and stability index (EAI/ESI), foaming capacity and stability (FC/FS), and gelation)) of Moringa oleifera protein isolates. The effect of ionic strength (0.2–1.0 M NaCl) and pH (2–10) on the functional properties were also investigated. Salt extraction & micellization produced an isolate with a high solubility at 0.8 M NaCl and pH 10 (98.1%, 91.8%), EAI at 0.6 M NaCl and pH 6 (56.2 m2/g, 77.0 m2/g), and ESI at 0.8 M NaCl and pH 4 (64.4 min, 243.5 min). Alkaline extraction & isoelectric precipitation resulted in an isolate with a high WHC at 0.6 M NaCl and pH 10 (5.8 g/g, 4.0 g/g), OAC (4.9 g/g), FC at 0.4 M NaCl and pH 2 (203.3%, 163.3%), and gelation at 0.2 M NaCl, 0.4 M NaCl, and pH 8 (20.0%). Both extraction methods can be applied in the valorization of M. oleifera seedcake. Micellized isolate could be used in food emulsions due to better emulsifying properties, while isoelectric isolate can be applied in meats and sauces, owing to better water holding and oil absorption capacity. M. oleifera protein isolates are promising plant-based proteins that can be used in food formulations or to replace animal-derived proteins in food. [ABSTRACT FROM AUTHOR]

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Protein was isolated by isoelectric precipitation from basil seeds (after mucilage and oil extraction) and investigated for its physicochemical and functional properties. The protein content of basil seed protein isolate (BPI) was 89.08%. High performance liquid chromatography (HPLC) showed presence of essential amino acids. Glutamic acid (17.40%), threonine (13.65%), and arginine (11.32%) were abundant. Sodium dodecyl sulphate polyacrylamide gel (SDS-PAGE) analysis showed molecular weights in the range of 11.5 to 77.6 kDa. Differential scanning calorimetry (DSC) of basil seed protein isolate revealed a high denaturation temperature (95.34 °C). The Fourier transform infrared spectroscopy (FTIR) indicated presence of amide I, II, and III groups. Characteristic peaks for β- sheet conformation were also observed. Results showed that BPI had high emulsifying ability index (298.4 m2/g) at pH 10. Solubility was lowest at pH 9 (10.69%). Functional properties such as protein solubility, foaming, and emulsification properties were high at pH 10. An increasing trend was observed from pH 2 to 5. High bulk density (0.799 g/ mL) and low water absorption capacity (0.51 g/ g) was observed.

Pea albumins are promising for their nutritional, biological, and techno-functional properties. However, this fraction is usually discarded in the industry due to its low protein content compared to globulin fraction and the presence of some anti-nutritional compounds. In the present study, we used an alternative method of pea protein extraction based on alkaline solubilization/isoelectric precipitation in which the reduction of pH was achieved by lactic acid fermentation using specific starters instead of mineral acids. Hence, the main objective of this study was to examine the protein profile and the content of anti-nutritional and nutritional active compounds in pea albumin-rich fractions obtained by the isoelectric extraction method without (control) or with fermentation with different lactic acid bacteria (Streptococcus thermophilus, Lactiplantibacillus plantarum, and their co-culture). Different pea cultivars (Cartouche, Ascension, and Assas) were used here for their differences in protein profile. The results revealed a higher total nitrogen content in albumin-rich fraction for fermented samples and, in particular, for co-culture. The majority of total nitrogen was determined as non-protein (~50%), suggesting the degradation of proteins by LAB to small peptides and amino acids, which were solubilized in the soluble fraction (albumin) as confirmed by size exclusion chromatography (SEC-HPLC) analysis. Moreover, the higher antioxidant activity of fermented albumin samples was attributed to the production of small peptides during extraction. Lactic acid fermentation also resulted in a significant reduction of trypsin inhibitor activity, α-galactoside, and phytic acid content of this fraction compared to control.

Abstract The emergence of thiol‐mediated uptake (TMU) as a powerful strategy to penetrate cells calls for the development of practical small‐molecule TMU tools for traceless delivery. Toward this goal, esters are explored here as bioreversible linkers between dynamic covalent cascade exchangers accounting for TMU and the protein of interest (POI). The method relies on α‐aryl‐α‐diazoamides that react with carboxylic acids of the POI to form esters that can be enzymatically hydrolyzed inside cells to release the native POI. A two‐step protocol is established for bioreversible conjugation of TMU tags to the POI. Despite the small number of tags attached to POIs to prevent isoelectric precipitation, POIs with traceless TMU tags are shown to efficiently enter cells not only in 2D culture but also in 3D spheroids mimicking deep tissue, confirming a key advantage of TMU. Uptake inhibition by various thiol‐reactive agents confirms the participation of cell‐surface thiols in cell penetration, i. e., the occurrence of TMU.

The possibility of reducing the amount of fresh water used during alkaline the pH-shift processing of salmon head (SH) and herring frame (HF) was evaluated with ultrasound (US) as a tool to mitigate its negative effects on protein yield. The role of water ratio and US for homogenate viscosity, mass yield, crude composition, functional properties and lipid oxidation of the SH and HF protein isolates were also investigated. Applying US during the solubilization step of the pH-shift process completely compensated for the reduced protein yield coming from using 3 rather than 6 volumes of water for HF, but not for SH. Using US had no negative effect on the composition and protein functionality of the HF protein isolate. However, it slightly increased its level of secondary lipid oxidation products. Altogether, applying US during the pH-shift processing at low water ratios can be a promising solution for more resource-smart valorization of herring side streams.

The present work used water-soluble protein concentrates from the microalga Tetradesmus obliquus to stabilize sunflower oil emulsions. Microalgal cells were disrupted by sonication, and proteins were separated from the biomass using two methods, isoelectric and solvent precipitations. The protein extracts were concentrated by lyophilization, and the concentrates were used to produce emulsions with three amounts of Tetradesmus obliquus protein concentrate (TobPC) (0.1, 0.5, and 1.0% w/v). Emulsions were homogenized through sonication and characterized for creaming index, optical microscopy, size distribution, ζ-potential, and rheology. Isoelectric precipitation resulted in TobPC with a high protein content (51.46 ± 2.37%) and a better dispersibility profile. Emulsion stability was higher for both the isoelectric TobPC and control systems than for the TobPC solvent. Solvent TobPC does not efficiently stabilize emulsions at low protein concentrations that showed microscopically larger oil droplets and flocculation spots. A high phase separation velocity was observed for solvent TobPC, probably due to the higher hydrodynamic droplet diameters. The increase in TobPC content in the emulsions resulted in more stable emulsions for all samples. Therefore, Tetradesmus obliquus protein concentrates are a potential emulsifying agent. [ABSTRACT FROM AUTHOR]

The possibility of replacing the very time and resource demanding salting out (SO) method with isoelectric precipitation (IP) during collagen extraction from common starfish and lumpfish was investigated. The effect of IP on yield, structural and functional properties of the collagens was therefore compared with SO. Application of IP resulted in a higher or similar collagen mass yield compared with SO from starfish and lumpfish, respectively. However, the purity of collagens recovered with IP was lower than those recovered with SO. Replacing SO with IP did not affect polypeptide pattern and tropohelical structural integrity of collagen from the two resources as revealed with SDS-PAGE and FTIR analysis. Thermal stability and fibril formation capacity of collagens recovered with IP were also well preserved. Overall, the results showed that the IP can be a promising resource smart alternative for the classic SO precipitation during collagen extraction from marine resources.

The effects of different mung bean protein isolation methods on the chemical composition, the physicochemical properties, and selected antinutritional factors of mung bean protein isolates were investigated. Six protein isolates were prepared by isoelectric precipitation at different extraction pH levels (pH 8 and 9), by micellization, and by hybrid isolation at varying salt concentrations (0.25 M, 0.50 M, 0.75 M). The extraction conditions affected the amount of antinutritive compounds of the isolates. Compared to mung bean flour, micellization reduced phytic acid content by approximately 48% and trypsin inhibitor activity by around 88%. The remaining phytic acid concentration of the isolates influenced their re-solubility, particularly under acidic conditions. The protein isolates exhibited significant differences in surface hydrophobicity and thermal characteristics, indicating structural modifications caused by the extraction methods. Micellization and extraction at pH 8 were identified as mildest isolation methods, as evidenced by the highest enthalpy values. SDS-PAGE analysis demonstrated an enrichment of globulins and comparable protein profiles among the isolates, suggesting that the observed differences arise from conformational changes rather than variations in protein composition. The product yield in protein extraction from mung beans ranged from 8% to 19%, emphasizing the importance of enhancing overall extraction efficiency or exploring the utilization of by-products obtained during the protein isolation process.

Protein isolates were obtained from marine hydrobionts by the method of isoelectric precipitation with a preliminary stage of protein alkaline solubilisation. Northern blue whiting was chosen as the raw material. Various technological modes of the solubilisation stage were used: the temperature of the reaction mixture was 4 or 20 °C, and the duration was 4 or 16 h. The yield of the product was 44–45% with a high content of the main component (protein) equal to about 95%. It has been shown that a decrease in the temperature and duration of the alkaline solubilisation stage provides the production of protein isolates with good technological properties, a low solubility, high swelling and high emulsifying ability, necessary for its use in the production of functional food products, including therapeutic and prophylactic effects. These technological properties are explained by a change in the composition and structure of the protein, the change being an increase in the content of essential amino acids and the proportion of α-helices in the polypeptide chain. The main patterns obtained will be used to obtain protein isolates from marine molluscs. [ABSTRACT FROM AUTHOR]

Edible insects represent a great alternative protein source but food neophobia remains the main barrier to consumption. However, the incorporation of insects as protein-rich ingredients, such as protein concentrates, could increase acceptance. In this study, two methods, isoelectric precipitation and ultrafiltration-diafiltration, were applied to produce mealworm protein concentrates, which were compared in terms of composition, protein structure and techno-functional properties. The results showed that the protein content of the isoelectric precipitation concentrate was higher than ultrafiltration-diafiltration (80 versus 72%) but ash (1.91 versus 3.82%) and soluble sugar (1.43 versus 8.22%) contents were lower. Moreover, the protein structure was affected by the processing method, where the ultrafiltration-diafiltration concentrate exhibited a higher surface hydrophobicity (493.5 versus 106.78 a.u) and a lower denaturation temperature (161.32 versus 181.44 °C). Finally, the ultrafiltration-diafiltration concentrate exhibited higher solubility (87 versus 41%) and emulsifying properties at pH 7 compared to the concentrate obtained by isoelectric precipitation. • Two methods were compared to produce mealworm protein isolates. • Higher protein content was produced by precipitation vs ultrafiltration. • Production method impacted protein denaturation and surface hydrophobicity. • Protein solubility was higher for ultrafiltration vs isoelectric precipitation. • Longer emulsion stability was obtained for ultrafiltration vs precipitation. [ABSTRACT FROM AUTHOR]

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.

Lupin meal presents great potential as an alternative plant-based source of proteins for human nutrition. In the present work, different conditions of extraction and purification were evaluated for production of lupin protein isolates. The results showed that the protein extraction yield was comparable at acidic and conventionally used alkaline extraction pH (37% vs. 40–45%, respectively). Proteins extracted were principally composed of globulins. The ionic strength negatively impacted the protein extractability at pH 2, whereas no significant differences were observed between extractions at 20 to 50 °C. The selected extraction conditions (pH 2 and 7) combined with purification by isoelectric precipitation or ultrafiltration process generated the isolate-grade products. Interestingly, further characterization revealed a partial denaturation of proteins extracted at pH 2 resulting in loss of protein solubility at pH 6 and 7 (10–50%), modifications in secondary structure, lower thermal stability, and formation of protein aggregates. However, foaming and emulsifying properties were generally similar for almost all lupin isolates. Further investigation might be of interest with regard to the extraction behaviours and structural and functional properties of specific lupin protein fractions. [ABSTRACT FROM AUTHOR]

Two different methods were employed to isolate proteins from defatted sesame cake, i.e., isoelectric point precipitation (SCIP) and protein micellization (SCM). The protein content of both isolates was similar (∼90%), whereas the SCIP appeared darker than the SCM. The lowest protein solubility was observed at pH 5.0–6.0 (isoelectric point region), with the SCM exhibiting higher solubility over the range of pH 2.0–10.0, compared to its isoelectric precipitation counterpart. Foaming capacity and stability improved with increasing NaCl (0.0–1.0 M) concentration and were higher for the SCM preparation. The emulsification properties were also pH dependent. The SCM retained its native structure, as evidenced by calorimetric, confocal microscopy and FTIR measurements. Fat absorption capacity appeared similar for both isolates, whereas the SCIP exhibited higher water retention capacity and in vitro protein digestibility, but lower levels of total phenolics than SCM. Upon heating, the paste-like rheological behavior of SCIP dispersions, which concurred with a more densely packed microstructure of smaller size protein aggregates, was maintained, while the liquid-like SCM dispersions gave stronger gel-like structures due to protein unfolding. Under reducing and non-reducing conditions, both isolates showed similar SDS-PAGE patterns, although some subtle compositional variations between the two isolates were noted for the low-abundance bands at higher loadings. Overall, the functional properties of sesame cake protein isolates were largely dependent on the preparation method; the SCM isolate displayed superior solubility, phenolic content, foaming properties and gelling capacity upon thermal processing, while SCIP preparation showed enhanced water retention and viscosity in aqueous dispersions and digestibility. [Display omitted] • Sesame cake protein isolates were obtained by isoelectric precipitation (SCIP) and micellization (SCM). • Both isolates (∼90% protein) had minor compositional difference and similar emulsion properties. • SCM had higher phenolics content, solubility, and better foaming properties than SCIP. • SCIP showed higher water retention capacity, digestibility and extent of denaturation than SCM. • SCIP aqueous dispersions behaved as weak gels, while SCM gave stronger gels only when heated. [ABSTRACT FROM AUTHOR]

The aim of this study was using the silver carp skin wastes as a potential source of collagen and recovering the soluble collagen in acid and enzyme solution by isoelectric precipitation method. The physicochemical properties of produced collagen investigated as well. Hence, collagen was extracted from the skin of silver carp by acidic and enzymatic methods. Then, soluble collagens were recovered using isoelectric precipitation (Isoelectric-Acid-soluble collagen (I-ASC) and Isoelectric-Pepsin-soluble collagen (I-PSC)) and salting-out (Acid-soluble collagen (ASC) and Pepsin-soluble collagen (PSC) methods. The results showed that the extraction yield and total protein content of ASC and PSC samples were higher than I-ASC and I-PSC samples. But the production yield was the same in all the samples. The high purity of I-ASC and I-PSC collagens represented different total protein content and extraction yield, however similar production yield. The SDSPAGE pattern confirmed the structure of I-ASC and I-PSC as type I collagen. In addition, the amino acid composition showed high amino acid content for I-PSC. It was estimated that the thermal denaturation temperatures for I-ASC and I-PSC samples laying at 28.70°C and 29.99°C, respectively. Finally, the investigation of collagen solubility at different pH levels and concentrations of NaCl showed that the solubility decreases with increasing ion concentration of the solution, and increases at the pH above and below the isoelectric point. Overall, the results showed that the isoelectric precipitation of soluble collagen produces a high-purity collagen protein that could be an alternative source to replace mammalian collagens. [ABSTRACT FROM AUTHOR]

This study aimed to determine the best extraction and precipitation conditions of Moringa oleifera Lam. leaf protein. The influence of pH (10, 11, 12) and the concentration of NaCl (0, 0.25, 0.5) for the protein extraction process were studied through a Completely Randomized Design (CRD) with factorial arrange 3². The combination of pH 11 and 12 with 0 M NaCl had the best yield (P<0.05). The treatment of pH 11 without NaCl followed a precipitation stage for its purification, and the effect of different levels of pH (4, 4.5, 5) and temperature (40, 60, 80 °C) were evaluated using a CRD with factorial arrange 2² and 6 central points. The temperature did not affect the yield of the process in a significant way and the amount of precipitate was maximized at pH 4 and 4.5. From 100 g of the dry leaf, 7.26±0.19 g of protein was isolated with a recovery of 26.93±0.22 g 100 g-1 from the total protein. Due to their astringency and bitterness, consuming large amounts of Moringa oleifera Lam leaves is not a solution; therefore, obtaining a leaf protein concentrate could be useful for diverse applications in nutritional supplements, and as raw material for functional products development. [ABSTRACT FROM AUTHOR]

Background and objectives: Providing information on protein structure and functionality is essential for evaluating the potential of specific agricultural commodities to be utilized as plant‐based protein sources. Amino acid composition, secondary structure, surface charge, thermal, and functional properties of proteins isolated from five local lentil landraces were investigated. Secondary objective of the study was to investigate if a relationship exists between the amino acid composition and the physicochemical or functional properties of the isolates. Findings: Aspartic acid and glutamic acid were found to be the dominant amino acids in the isolates while they were poor in methionine. Denaturation temperatures of isolates ranged between 96–108°C and their secondary structure mainly consisted of β‐sheet. Emulsion capacity, emulsifying activity (EAI), and emulsion stability indices (ESI) of isolates were found to be between 403.8–468.2 g oil/g protein, 18.8–24.2 m2/g, and 43.4–125.5 min, respectively. Foaming capacity of the isolates changed between 71% and 91% whereas their least gelation concentration varied between 110 and 150 g/L. Conclusions: Yusufhan isolate which had relatively higher acidic amino acid content showed the highest net charge and solubility at acidic pH. Tigris isolate which had higher hydrophobic amino acid content compared to the other isolates showed relatively high thermal stability, EAI and ESI. Significance and novelty: Findings of the study make a contribution toward the potential use of local lentil landraces as sources for extracting protein‐based ingredients. [ABSTRACT FROM AUTHOR]

Protein isolates were obtained from marine hydrobionts by the method of isoelectric precipitation with a preliminary stage of protein alkaline solubilisation. Northern blue whiting was chosen as the raw material. Various technological modes of the solubilisation stage were used: the temperature of the reaction mixture was 4 or 20 °C, and the duration was 4 or 16 h. The yield of the product was 44–45% with a high content of the main component (protein) equal to about 95%. It has been shown that a decrease in the temperature and duration of the alkaline solubilisation stage provides the production of protein isolates with good technological properties, a low solubility, high swelling and high emulsifying ability, necessary for its use in the production of functional food products, including therapeutic and prophylactic effects. These technological properties are explained by a change in the composition and structure of the protein, the change being an increase in the content of essential amino acids and the proportion of α-helices in the polypeptide chain. The main patterns obtained will be used to obtain protein isolates from marine molluscs.

In this work, the structural and functional properties of proteins from black and yellow quinoa were assessed as well as the in vitro digestibility. Black quinoa flours contained higher amounts of crude fiber and lower amounts of total starch compared to the yellow counterpart. Structurally, electrophoretic SDS-PAGE bands corresponding to 50 kDa 11S globulin, and 55 kDa protein (under non-reducing conditions), and 31–33 kDa (under reducing conditions) were observed in both isolates. Fat absorption and water solubility indexes were comparatively lower in the black quinoa protein isolate. Both isolates showed a good nitrogen solubility index and emulsifying activity. In vitro protein digestibility was similar for both varieties (>95%). The addition of the protein isolates obtained from quinoa flours could be considered as a good alternative to increase the protein content of different foods taking advantage of key functional properties such as nitrogen solubility index and emulsifying activity.

Lupin meal presents great potential as an alternative plant-based source of proteins for human nutrition. In the present work, different conditions of extraction and purification were evaluated for production of lupin protein isolates. The results showed that the protein extraction yield was comparable at acidic and conventionally used alkaline extraction pH (37% vs. 40–45%, respectively). Proteins extracted were principally composed of globulins. The ionic strength negatively impacted the protein extractability at pH 2, whereas no significant differences were observed between extractions at 20 to 50 °C. The selected extraction conditions (pH 2 and 7) combined with purification by isoelectric precipitation or ultrafiltration process generated the isolate-grade products. Interestingly, further characterization revealed a partial denaturation of proteins extracted at pH 2 resulting in loss of protein solubility at pH 6 and 7 (10–50%), modifications in secondary structure, lower thermal stability, and formation of protein aggregates. However, foaming and emulsifying properties were generally similar for almost all lupin isolates. Further investigation might be of interest with regard to the extraction behaviours and structural and functional properties of specific lupin protein fractions.

Fractionation is a potential way to valorize under-utilized fishes, but the quality of the resulting fractions is crucial in terms of their applicability. The aim of this work was to study the quality of protein isolates and hydrolysates extracted from roach (Rutilus rutilus) and Baltic herring (Clupea harengus membras) using either pH shift or enzymatic hydrolysis. The amino acid composition of protein isolates and hydrolysates mostly complied with the nutritional requirements for adults, but protein isolates produced using pH shift showed higher essential to non-essential amino acid ratios compared with enzymatically produced hydrolysates, 0.84–0.85 vs. 0.65–0.70, respectively. Enzymatically produced protein hydrolysates had a lower total lipid content, lower proportion of phospholipids, and exhibited lower degrees of protein and lipid oxidation compared with pH-shift-produced isolates. These findings suggest enzymatic hydrolysis to be more promising from a lipid oxidation perspective while the pH-shift method ranked higher from a nutrient perspective. However, due to the different applications of protein isolates and hydrolysates produced using pH shift or enzymatic hydrolysis, respectively, the further optimization of both studied methods is recommended.

Fishmeal factories produce a large amount of wastewater during the production process, which contains protein. The aim of this study was to recover protein from the effluent of fishmeal factory by isoelectric method and investigate the functional properties of recycled protein. The effluent sample was obtained from fishmeal production plant in the Konarak city and proximate composition analysis of the effluent sample was investigated. The protein in the effluent was recycled using the isoelectric precipitation method and pH changing. The functional properties of the recovered protein including solubility, oil and water holding capacity, emulsifying index and emulsion stability, foam formation and foam stability were measured using standard methods procedures. The results showed that the amount of protein in the treated sample has no any significant differences under the effluent effects (p >0.05). The highest and lowest solubility were obtained at pH 2 and pH 6, respectively. The water and oil holding capacity of recycled protein was 0.45 and 0.4 ml/g, respectively. The highest emulsion activity was observed at pH 10 and the highest foam formation capacity at pH 2. The highest emulsion stability was observed at pH 2 and the highest foam stability was observed at pH 2 and 10. Recycled protein showed good functional properties and changed with pH, but not all properties followed a specific trend. [ABSTRACT FROM AUTHOR]

Jatropha seed cake is a by-product of biodiesel industry which is rich in proteins and carbohydrates and contains many bioactive compounds. Besides having a good protein quality, the essential amino acid content (except lysine) is also high in Jatropha seed cake, and therefore, Jatropha proteins can be exploited for many technical applications. The major hindrance for its use as a protein supplement is the presence of anti-nutritional factors and toxins, especially the phorbol esters. The detoxification of Jatropha seed cake for the removal of phorbol esters has been shown in our earlier studies. Proteins were extracted from the detoxified Jatropha seed cake and analyzed for amino acid content. Various parameters such as temperature, solubilization pH, precipitation pH and extraction time were studied for their effect on protein content, and the process was optimized using response surface methodology among 5 best samples selected based on protein content and protein yield from dry concentrates. The amount of dry matter, protein content and protein yield of 17.1%, 41.98% and 38.66%, respectively, was obtained under the optimized conditions of 60 °C temperature, solubilization pH 11.0, precipitation pH 4.41 and extraction time of 0.78 h. Amino acid contents revealed that the extracted samples contained a higher concentration of essential amino acids, especially leucine (4.40 ± 0.98 g/100 g). The results indicated that the protein extraction procedure from Jatropha seed cake affected the amino acid content, yet the values were close to FAO/WHO reference protein, and thus, the Jatropha proteins can be explored further for their use as feed supplement. [ABSTRACT FROM AUTHOR]

A reduced‐fat coconut yoghurt (RFY) was developed. The proximate composition of whole‐fat coconut yoghurt (WFY) was significantly different from that of RFY. The storage modulus G′, water‐holding capacity (WHC), yield stress (τo) and consistency coefficient (k) of RFY were higher than those of WFY. The RFY exhibited lower lipid oxidation as the storage period increased. The RFY showed better viability of Lactobacillus bulgaricus and Streptococcus thermophilus. Furthermore, the micrographs of WFY showed larger pores than those of RFY. The sensory panellist preferred RFY (6.78 ± 1.38) to WFY (5.38 ± 1.68). Hence, RFY can be considered as a natural food alternative for vegans. [ABSTRACT FROM AUTHOR]

• Ultrasonication during protein extraction enabled reducing water ratio to half. • The effect of ultrasound on the yield was dependent on the type of side stream. • Applying ultrasound did not alter protein functionality within the same water ratio. • Ultrasonication slightly increased lipid oxidation in the recovered proteins. The possibility of reducing the amount of fresh water used during alkaline the pH-shift processing of salmon head (SH) and herring frame (HF) was evaluated with ultrasound (US) as a tool to mitigate its negative effects on protein yield. The role of water ratio and US for homogenate viscosity, mass yield, crude composition, functional properties and lipid oxidation of the SH and HF protein isolates were also investigated. Applying US during the solubilization step of the pH-shift process completely compensated for the reduced protein yield coming from using 3 rather than 6 volumes of water for HF, but not for SH. Using US had no negative effect on the composition and protein functionality of the HF protein isolate. However, it slightly increased its level of secondary lipid oxidation products. Altogether, applying US during the pH-shift processing at low water ratios can be a promising solution for more resource-smart valorization of herring side streams. [ABSTRACT FROM AUTHOR]

Novel vegetable proteins, like those extracted from abundant raw materials (grass) or agri-food by-products and waste streams (oilseed meals), are expected to be used as replacers for animal-derived proteins, due to higher production efficiency, reduced life cycle environmental impact and possibility to meet consumers' dietary or cultural preferences. Although having a versatile functionality (emulsifying, foaming, gelling, texturizing agents), application of proteins is limited since their properties highly depend on their structure and composition, environmental factors (pH, ionic strength, presence of other micro- and macro-molecules in food matrices) and isolation method and conditions. The objective of this article is to review the current techniques used to isolate the proteins from vegetable raw materials and comment on the influence of extraction method and conditions (pH, ionic strength, extraction media temperature, extraction time, etc.) on protein properties (yield, purity, appearance, solubility, denaturation degree, emulsification efficiency, etc.). The utilization of novel technologies such as ultrasound assisted extraction, electro-activation technique and approaches (enzyme-assisted extraction) to improve protein extraction yield or functionality was also discussed.

Pea albumins are promising for their nutritional, biological, and techno-functional properties. However, this fraction is usually discarded in the industry due to its low protein content compared to globulin fraction and the presence of some anti-nutritional compounds. In the present study, we used an alternative method of pea protein extraction based on alkaline solubilization/isoelectric precipitation in which the reduction of pH was achieved by lactic acid fermentation using specific starters instead of mineral acids. Hence, the main objective of this study was to examine the protein profile and the content of anti-nutritional and nutritional active compounds in pea albumin-rich fractions obtained by the isoelectric extraction method without (control) or with fermentation with different lactic acid bacteria ( Streptococcus thermophilus, Lactiplantibacillus plantarum , and their co-culture). Different pea cultivars (Cartouche, Ascension, and Assas) were used here for their differences in protein profile. The results revealed a higher total nitrogen content in albumin-rich fraction for fermented samples and, in particular, for co-culture. The majority of total nitrogen was determined as non-protein (~50%), suggesting the degradation of proteins by LAB to small peptides and amino acids, which were solubilized in the soluble fraction (albumin) as confirmed by size exclusion chromatography (SEC-HPLC) analysis. Moreover, the higher antioxidant activity of fermented albumin samples was attributed to the production of small peptides during extraction. Lactic acid fermentation also resulted in a significant reduction of trypsin inhibitor activity, α-galactoside, and phytic acid content of this fraction compared to control., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Emkani, Moundanga, Oliete and Saurel.)

Isoelectric precipitation and ultrafiltration were investigated for their potential to produce protein products from lentils. Higher protein concentrations were obtained when ultrafiltration was used (> 90%), whereas isoelectric precipitation resulted in higher contents of dietary fibre and some minerals (i.e., sodium and phosphorus). Differences in the functional properties between the two ingredients were found as the isoelectric precipitated ingredient showed lower protein solubilities over the investigated pH range (from 3 to 9) which can be linked to the slightly higher hydrophobicity values (2688.7) and total sulfhydryl groups (23.9 µM/g) found in this sample. In contrast, the protein ingredient obtained by ultrafiltration was superior with regard to its solubility (48.3%; pH 7), fat-binding capacity (2.24 g/g), water holding capacity (3.96 g/g), gelling properties (11%; w/w), and foam-forming capacity (69.6%). The assessment of the environmental performance showed that both LPIs exhibited promising properties and low carbon footprints in comparison to traditional dairy proteins. [ABSTRACT FROM AUTHOR]

In addition to small amounts of minerals and carbohydrates, most of the dry matter of chicken egg white is protein, making egg white an ideal resource for obtaining food proteins. Ovalbumin (OVA), which accounts for more than 50% of the total egg white protein, is one of the most widely studied food proteins due to its multiple functional properties, and it has also been used as a model protein molecule in many research fields. The objective of this study was to develop a simple and rapid method for the purification of OVA from egg whites on large scale. First, OVA was separated from ovomucin, ovotransferrin, and ovomucoid by polyethylene glycol (PEG) concentration, using the following optimal parameters: the PEG concentration was 15%, the pH was 6.5, the salt concentration was 100 mmol/L, and the operating temperature was 10°C. The OVA-rich supernatant obtained from PEG precipitation was further purified by isoelectric precipitation at a pI of 4.5 and a temperature of 4°C, and the purified OVA was obtained with at a purity of 95.1% by HPLC, with a yield of 46.4%. After the extraction of OVA, the PEG solution was vacuum dried and then utilized cyclically in the PEG precipitation steps. The whole purification process could be finished within 2 to 3 h at a scale of several kilograms of egg white. This method has the advantages of rapidity, simplicity, low cost, and ease of scalability. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to establish a rapid and simple method for isolating exosomes from raw bovine milk and to compare the quality of the isolated exosomes with those isolated by a standard method involving ultracentrifugation (UC). Methods: To remove caseins, which are major milk proteins consisting more than 80% of milk protein (35% in human breast milk) and hamper isolation and purification of exosomes, hydrochloride (HCl) was added to milk for isoelectric precipitation (IP). The effects of acidification on morphological features, particle size distribution, surface charge, and exosome surface proteins were analyzed by electron microscopy, tunable resistive pulse sensing (TRPS), and Western blot (WB) analysis, respectively. Results: Electron microscopy showed that some of the exosomes isolated using IP had rough surfaces; most exosomes were successfully isolated without breakage, and their morphological features were similar to those of exosomes isolated by UC. TRPS showed that their surface charge and peaks (mode) for particle size distribution did not significantly differ between both methods. WB analysis using antibodies against the exosome surface marker proteins - milk fat globule-epidermal growth factor 8 (MFG-E8) and CD63 - revealed that the structures of exosome surface proteins were not affected by adding HCl. Conclusions: IP can be used to remove caseins to reduce operation time. This method will be useful for efficient isolation and purification of bovine milk exosomes and contribute to progression of research on health management of dairy cattle and drug delivery systems in human medicine, which require large amounts of milk exosomes. [ABSTRACT FROM AUTHOR]

In this work, the structural and functional properties of proteins from black and yellow quinoa were assessed as well as the in vitro digestibility. Black quinoa flours contained higher amounts of crude fiber and lower amounts of total starch compared to the yellow counterpart. Structurally, electrophoretic SDS-PAGE bands corresponding to 50 kDa 11S globulin, and 55 kDa protein (under non-reducing conditions), and 31–33 kDa (under reducing conditions) were observed in both isolates. Fat absorption and water solubility indexes were comparatively lower in the black quinoa protein isolate. Both isolates showed a good nitrogen solubility index and emulsifying activity. In vitro protein digestibility was similar for both varieties (>95%). The addition of the protein isolates obtained from quinoa flours could be considered as a good alternative to increase the protein content of different foods taking advantage of key functional properties such as nitrogen solubility index and emulsifying activity. [ABSTRACT FROM AUTHOR]

Abstract A combination of isoelectronic precipitation and electrolyzed water treatment (IP-EWT) process was use for simultaneous recovery of protein and phosphorus compounds from heat-stabilized defatted rice bran (HSDFRB). The highest protein content (65.1 w/w%) recovery ratio (over 50%) of protein concentrate were attained by two-stage protein extraction with IP-EWT. Analysis of amino-acid composition demonstrated excellent amino acid value (76.6%) in the protein fraction than those of commercial cereals such as rice (61%), wheat (39%), and corn (31%). In addition, according to SDS-PAGE and immunoblotting analysis, neither rice allergenic protein nor heavy metals were detected in either HSDFRB or protein fractions extracted by IP-EWT. These results suggest that as an eco-friendly process, this combined (IP-EWT) process is suitable for practical recovery of highly concentrated and safe protein from HSDFRB without using enzymes or chemicals such as organic solvents, buffering agents, and surfactants. Highlights • Rice protein concentrate was recovered and purified by using IP-EWT process. • Excellent amino acid value (76.6%) was indicated in the protein fraction. • Allergenic protein were not detected in HSDFRB and protein fractions. • IP-EWT process is suitable for recovery of highly concentrated and safe rice protein. [ABSTRACT FROM AUTHOR]

Dry fractionated faba bean protein-rich flour (FPR) produced by milling/air classification, and faba bean protein isolate (FPI) produced by acid extraction/isoelectric precipitation were compared in terms of composition, techno-functional properties, nutritional properties and environmental impacts. FPR had a lower protein content (64.1%, dry matter (DM)) compared to FPI (90.1%, DM), due to the inherent limitations of air classification. Of the two ingredients, FPR demonstrated superior functionality, including higher protein solubility (85%), compared to FPI (32%) at pH 7. Foaming capacity was higher for FPR, although foam stability was similar for both ingredients. FPR had greater gelling ability compared to FPI. The higher carbohydrate content of FPR may have contributed to this difference. An amino acid (AA) analysis revealed that both ingredients were low in sulfur-containing AAs, with FPR having a slightly higher level than FPI. The potential nutritional benefits of the aqueous process compared to the dry process used in this study were apparent in the higher in vitro protein digestibility (IVPD) and lower trypsin inhibitor activity (TIA) in FPI compared to FPR. Additionally, vicine/convicine were detected in FPR, but not in FPI. Furthermore, much lower levels of fermentable oligo-, di- and monosaccharides, and polyols (FODMAPs) were found in FPI compared to FPR. The life cycle assessment (LCA) revealed a lower environmental impact for FPR, partly due to the extra water and energy required for aqueous processing. However, in a comparison with cow’s milk protein, both FPR and FPI were shown to have considerably lower environmental impacts.

The effects of different mung bean protein isolation methods on the chemical composition, the physicochemical properties, and selected antinutritional factors of mung bean protein isolates were investigated. Six protein isolates were prepared by isoelectric precipitation at different extraction pH levels (pH 8 and 9), by micellization, and by hybrid isolation at varying salt concentrations (0.25 M, 0.50 M, 0.75 M). The extraction conditions affected the amount of antinutritive compounds of the isolates. Compared to mung bean flour, micellization reduced phytic acid content by approximately 48% and trypsin inhibitor activity by around 88%. The remaining phytic acid concentration of the isolates influenced their re-solubility, particularly under acidic conditions. The protein isolates exhibited significant differences in surface hydrophobicity and thermal characteristics, indicating structural modifications caused by the extraction methods. Micellization and extraction at pH 8 were identified as mildest isolation methods, as evidenced by the highest enthalpy values. SDS-PAGE analysis demonstrated an enrichment of globulins and comparable protein profiles among the isolates, suggesting that the observed differences arise from conformational changes rather than variations in protein composition. The product yield in protein extraction from mung beans ranged from 8% to 19%, emphasizing the importance of enhancing overall extraction efficiency or exploring the utilization of by-products obtained during the protein isolation process., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

In the current study, bacteria isolated from sea water samples of Murdeshwar, Karnataka, were screened for the production of alkaline protease by culturing them onto skim milk agar media. Of the isolated bacteria, Bacillus subtilis , Pseudomonas aeruginosa and Alcaligenes faecalis showed distinct zones of hydrolysis due to enzyme production. They were each inoculated into enzyme production media under submerged fermentation conditions at 37 °C for 48 h with a constant agitation of 120 rpm. Partial purification of alkaline protease was carried out by isoelectric precipitation. Enzyme activity was determined under varying conditions of pH, incubation temperature, different substrates, carbon and nitrogen sources and salt concentrations using sigma’s universal protease activity assay. Enzyme immobilization was carried out using 2% Sodium alginate and 0.1 M ice cold CaCl 2 and its activity under varying pH, temperature conditions and detergent compatibility was assayed. Efficacy of enzyme in stain removal was tested and haemolysis was observed within of 60 s which resulted in removal of the stain. Among the three organisms, enzyme from Bacillus subtilis showed highest activity in all cases indicating that it was the most ideal organism for enzyme production. [ABSTRACT FROM AUTHOR]

A technology of foam fractionation coupled with isoelectric precipitation was developed for effectively recovering casein from its highly diluted solution without using any surfactants as stabilizers due to its poor surface activity. The results showed that foam stability could be improved by using the pore diameter of gas distributor 125 μm and increasing the liquid phase height to 1750 mm. In the two-stage continuous foam fractionation, the enrichment ratio and the recovery percentage of casein were obtained as high as 12.1 and 92.3%, respectively. Then, the foamate was treated by precipitation and the supernatant could be used as the feed solution of the first stage foam fractionation. By using the coupled technology, the enrichment ratio was further increased to 52.6 and the recovery percentage was 91.7%. The concentration of casein 0.01 g/L and its mass percent 5% were got in the residual solution and the precipitated solution, respectively. [ABSTRACT FROM AUTHOR]

Collagen was extracted from bigeye tuna (Thunnus obesus) skins by salting-out (PSC-SO) and isoelectric precipitation (PSC-IP) methods. The yield of the PSC-IP product was approximately 17.17% (dry weight), which was greater than the yield obtained from PSC-SO (14.14% dry weight). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated that collagen from bigeye tuna skin belongs to collagen type I. Inductively coupled plasma mass spectrometry results indicate that the heavy metal abundance in PSC-IP was lower than the maximum acceptable amounts according to Chinese regulatory standards. In addition, results from a methylthiazolyldiphenyl-tetrazolium bromide assay and an in vitro scratch assay demonstrated that PSC-IP could promote the proliferation and migration of NIH-3T3 fibroblasts. Overall, results suggest PSC-IP could be used to rapidly extract collagen from marine by-products instead of traditional salting-out methods. Collagen from bigeye tuna skin may also have strong potential for cosmetic and biomedical applications.

In this study, effects of NaCl concentrations (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 M) and pH (3.0, 5.0, 7.0, and 8.0) on the physico-chemical and functional properties of potato protein concentrates extracted from potato fruit juice (PFJ) using ammonium sulfate precipitation (ASP) and isoelectric precipitation (IEP) were investigated. The total polyphenol content of potato protein concentrates extracted by IEP (IEPP) was 2.5 times of that of potato protein concentrates extracted by ASP (ASPP), which resulted in the color of IEPP darker than that of ASPP. More protein fractions (74, 62, and 35 kDa) were found in IEPP compared to ASPP. ASPP exhibited higher solubility than IEPP. The emulsifying properties of ASPP and IEPP increased along with the increasing NaCl concentration. ASPP and IEPP showed the lowest emulsifying properties and foaming ability at pH 5.0. While the foaming stability of ASPP and IEPP achieved the maximum and minimum at pH 5.0, respectively. Two endothermic peaks were observed in ASPP at pH 3.0, 8.0, and higher NaCl concentration (≥0.6 M), while more than two endothermic peaks were observed in IEPP at all NaCl concentrations (0.2–1.0 M) and pH values (3.0, 5.0, 7.0, and 8.0). The glutamic acid concentration of ASPP and aspartic acid concentration of IEPP were the highest, while histidine was the lowest according to the amino acid profile of both ASPP and IEPP. In terms of an essential amino acid index with respect to a reference protein of FAO/WHO, the nutritional values of IEPP were higher than those of ASPP. [ABSTRACT FROM AUTHOR]

To understand if and how extraction conditions influence properties of molded protein films, Crambe abyssinica protein concentrates were produced from deoiled seed meal under various extraction conditions. Properties of the resulting hot compression molded films were evaluated through the molecular weight distribution, protein polymerization behavior and tensile tests. Precipitated protein concentrates demonstrated higher protein content and a pronounced shift to higher molecular weight distributions and reduced solubility on heating, indicating increased protein polymerization compared to those from lyophilized supernatants. Thermally processed films from isoelectrically precipitated protein concentrates show a high resistance to extraction with a combination of reducing agent and denaturant, indicating the presence of non-disulfide covalent cross linking. Also, tensile strength was higher in concentrates from precipitated proteins compared to those from supernatants. The protein concentrates resulting in thermally processed films with a high protein content, the highest levels of protein-protein interaction and high tensile strength were based on alkaline extraction and isoelectric precipitation. Therefore, a combination of alkali extraction and isoelectric precipitation is recommended to produce protein concentrates for molded film production. [ABSTRACT FROM AUTHOR]

Ghee residue (GR) is the by-product of ghee industry, possessing huge nutritional potential that still lacks in its valorization. This investigation was aimed to recover proteins from GR, by processing with different treatments such as boiling water (30 min), washing with 50% alcohol, isoelectric precipitation, boiling in sodium tri polyphosphate concentration (STPP) solution (1, 2, 3% strength, 30 min) and employing ultrafiltration membrane process. Extraction of proteins from the processed ghee residue (PGR) was observed to be of lower proteins purity. Commonly used acid precipitation method also failed to precipitate proteins from GR, but ultrafiltration resulted in efficient concentration of these proteins. Decrease in concentration of ghee residue and increase in dissolving time, significantly increased solubility of GR. Similarly, addition of sodium tri polyphosphate concentration (STPP) and dissolving time also significantly improved GR solubility. Ghee residue solution was concentrated up to 5.2 ultrafiltration (UF) folds, after that membrane flux approached to zero. Further, ultrafiltration of GR solution resulted in 97% recovery and 70% purity of GR proteins. Findings of this study could significantly increase the profit of organized dairy plants and significantly reduce the waste disposal problem. About 1,00,000 tonnes of proteins can be recovered annually from GR only; that can satisfy yearly protein requirement of about 45,66,000 healthy persons and might help the nation in combating severe problem of protein energy malnutrition. [ABSTRACT FROM AUTHOR]

A solvent-free electrostatic separation method was employed to separate navy bean flour (NBF) into protein-rich (PR) and starch-rich (SR) fractions. The physicochemical properties of NBF and separated fractions were compared to proteins (navy bean isolate (NBI) and 7S globulin) prepared using a wet process. Gel electrophoresis confirmed that the protein distribution in the isolated fractions was similar to that of NBF. The protein profile of NBI and 7S globulin was found to be devoid of certain proteins that were found in the NBF and PR fraction. Amino acid analysis revealed that the NBI and 7S globulin had a lower content of sulfur-containing amino acids compared to NBF and the electrostatically isolated fractions. CD and fluorescence spectroscopy confirmed that denaturation of the proteins during the acid precipitation is likely. This novel solvent-free electrostatic separation process preserves the native protein structure found in NBF and improves the recovery of some of the smaller MW proteins. [ABSTRACT FROM AUTHOR]