Characterization of soybean proteins by HPLC

Near-infrared hyperspectral imaging for online measurement of the viability detection of naturally aged watermelon seeds

The viability status of seeds before sowing is important to farmers as it allows them to make yield predictions. Monitoring the seed quality in a rapid and nondestructive manner may create a perfect solution, especially for industrial sorting applications. However, current offline laboratory-based strategies employed for the monitoring of seed viability are time-consuming and thus cannot satisfy industrial needs where there is a substantial number of seeds to be analyzed. In this study, we describe a prototype online near-infrared (NIR) hyperspectral imaging system that can be used for the rapid detection of seed viability. A wavelength range of 900-1700 nm was employed to obtain spectral images of three different varieties of naturally aged watermelon seed samples. The partial least square discriminant analysis (PLS-DA) model was employed for real-time viability prediction for seed samples moving through a conveyor unit at a speed of 49 mm/sec. A suction unit was further incorporated to develop the online system and it was programmatically controlled to separate the detected viable seeds from nonviable ones. For an external validation sample set showed classification accuracy levels of 91.8%, 80.7%, and 77.8% in relation to viability for the three varieties of watermelon seed with healthy seedling growth. The regression coefficients of the classification model distinguished some chemical differences in viable and nonviable seed which was verified by the chromatographic analysis after the detection of the proposed online system. The results demonstrated that the developed online system with the viability prediction model has the potential to be used in the seed industry for the quality monitoring of seeds.

Investigation of enzymatic hydrolysis kinetics of soy protein isolate: laboratory and semi-industrial scale

Using parameters of optimal conditions from laboratory experiments often results in the loss of significant time and resources when trying to scale up the process. In this study, the comparison of results of laboratory and semi-industrial experiments of enzymatic hydrolysis of soy protein isolate is considered. The kinetics of peptides accumulation was investigated by colorimetric method in both microtube (volume reaction is 0.7 ml, 7.14 mg/ml of substrate, incubation in solid state thermostat) and industrial homogenizer (volume reaction is 4,000 ml, 100 mg/ml of substrate, rotor-stator type mixer). The enzyme preparation Protosubtilin G3x (main component is subtilisin) was used as an analogue of the Alcalase preparation, which is already widely used in the food industry. It was found that the pH and the number of proteolytic units in the reaction mixture of both scales had slightly different results of the kinetics, while the temperature showed significantly one. The laboratory scale of the reaction had a wide range of optimal temperature (40-60 ∘ C, 30 ∘ C showed slowest rate of kinetics reaction), whereas the semi-industrial scale had 50 ∘ C of optimal temperature (30, 40, 60 ∘ C had the same kinetics). It also was found that maintaining the pH value of the reaction mixture was not mandatory. The obtained results indicate the need to refine the process conditions using semi-industrial experiments before attracting industrial-scale resources. In the case of selection of conditions for the hydrolysis of soy protein isolate in production, it is necessary first of all to take into account the reaction temperature as the most irreproducible parameter when scaling.

Identification and Quantification of Major Faba Bean Seed Proteins

Faba bean (Vicia faba L.) holds great importance for human and animal nutrition for its high protein content. However, better understanding of its seed protein composition is required in order to develop cultivars that meet market demands for plant proteins with specific quality attributes. In this study, we screened 35 diverse Vicia faba genotypes by employing the one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1D SDS-PAGE) method, and 35 major protein bands obtained from three genotypes with contrasting seed protein profiles were further analyzed by mass spectrometry (MS). Twenty-five of these protein bands (MW range: ∼ 9-107 kDa) had significant (p ≤ 0.05) matches to polypeptides in protein databases. MS analysis showed that most of the analyzed protein bands contained more than one protein type and, in total, over 100 proteins were identified. These included major seed storage proteins such as legumin, vicilin, and convicilin, as well as other protein classes like lipoxygenase, heat shock proteins, sucrose-binding proteins, albumin, and defensin. Furthermore, seed protein extracts were separated by size-exclusion high-performance liquid chromatography (SE-HPLC), and percentages of the major protein classes were determined. On average, legumin and vicilin/convicilin accounted for 50 and 27% of the total protein extract, respectively. However, the proportions of these proteins varied considerably among genotypes, with the ratio of legumin:vicilin/convicilin ranging from 1:1 to 1:3. In addition, there was a significant (p < 0.01) negative correlation between the contents of these major fractions (r = -0.83). This study significantly extends the number of identified Vicia faba seed proteins and reveals new qualitative and quantitative variation in seed protein composition, filling a significant gap in the literature. Moreover, the germplasm and screening methods presented here are expected to contribute in selecting varieties with improved protein content and quality.

Molecular changes of phenolic-protein interactions in isolated proteins from flaxseed and soybean using Native-PAGE, SDS-PAGE, RP-HPLC, and ESI-MS analysis

The effects of protein-phenolic interactions on the molecular characteristics of soybean and flaxseed proteins were investigated. Proteins were isolated from soybean and flaxseed using isoelectric precipitation, followed by extraction of free and bound phenolics. The effects of elimination of the phenolic compounds on molecular characteristics of the protein isolates were studied using reversed phase-high performance liquid chromatography (RP-HPLC), Native and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and electron spray ionization-mass spectrometry (ESI-MS). The Native-PAGE fractions from isolated proteins from full-fat flaxseed and soybean revealed that protein migration was affected by removal of bound phenolics. SDS-PAGE from full-fat and defatted protein isolates of flaxseed and soybean revealed that the removal of bound phenolics affected the molecular characteristics of protein subunits. Soybean protein isolates had protein-phenolic interactions through acidic and basic subunits. RP-HPLC and ESI-MS showed that the removal of bound and free phenolics had only minor effects on the molecular characteristics of isolated proteins from defatted and full-fat soybean. With respect to isolated proteins from flaxseed, the removal of bound phenolics showed little effect on the electrophoretic behavior of the proteins or the protein subunits. PRACTICAL APPLICATIONS: Phenolic-protein and phenolic-lipid-protein interactions may affect the nutritional, physicochemical, and functional properties of isolated proteins from food in flaxseed and soybean.

Rapid differentiation of Ralstonia solanacearum avirulent and virulent strains by cell fractioning of an isolate using high performance liquid chromatography

Ralstonia solanacearum is one of the most destructive plant bacterial pathogens worldwide. The population dynamics and genetic stability are important issues, especially when an avirulent strain is used for biocontrol. In this study, we developed a rapid method to differentiate the virulent and avirulent strains of R. solanacearum and to predict the biocontrol efficiency of an avirulent strain using high performance liquid chromatography (HPLC). Three chromatographic peaks P1, P2 and P3 were observed on the HPLC spectra among 68 avirulent and 28 virulent R. solanacearum strains. Based on the HPLC peaks, 96 strains total were assigned to three categories. For avirulent strains, the intense peak is P1, while for virulent strains, P3 is the majority. Based on the HLPC spectra of R. solanacearum strains, a chromatography titer index (CTI) was established as CTIi = Si/(S1+S2+S3) × 100% (i represents an individual HPLC peak; S1, S2 and S3 represent peak areas of P1, P2 and P3, respectively). The avirulent strains had high values of CTI1 ranging from 63.6 to 100.0%, while the virulent strains displayed high values of CTI3 ranging from 90.2 to 100.0%. Biological inoculation studies of 68 avirulent strains revealed that the biocontrol efficacy was the best when CTI1 = 100%. The purity and genetic stability of R. solanacearum strains were confirmed in the P1 fraction of avirulent strain FJAT-1957 and P3 fraction of virulent strain FJAT-1925 after 30 generations of consecutive subculture. These results confirmed that fractioning by HPLC and their deduced CTI can be used for rapid and efficient evaluation and prediction of an isolate of R. solanacearum. To the best of our knowledge, this is the first report that HPLC fractioning can be used for rapid differentiation of virulent and avirulent strains of R. solanacearum.

Impact of pH on molecular structure and surface properties of lentil legumin-like protein and its application as foam stabilizer

The capacity of a protein to form and stabilize foams and emulsions depends on its structural characteristics and its physicochemical properties. The structural properties of lentil legumin-like protein including molecular weight, hydrodynamic size, surface charge and hydrophobicity, and conformation were studied in relation to its air-water interfacial behaviors. Kinetics study suggested that the foaming stability was closely related to the surface conformation of the protein that strongly affected adsorption and re-organization of the protein layer at the air-water interface. Foams prepared at neutral pH showed dense and strong networks at the interface, where combination of the α-helix secondary structure, medium hydrodynamic molecular size, and balance between solubility/hydrophobicity all contributed to the formation of such strong protein network at the interface. At pH 5.0, the protein formed a dense and thick network composed of randomly aggregated protein particles at the air-water interface. Whereas at pH 3.0, the unordered structure increased intra-protein flexibility producing a less compact and relaxed interface that reduces elasticity modulus with time and reduced foam resistance against collapse. This research revealed that lentil legumin-like protein could form long-life foams at mild acidic and neutral pH. The potential for use of lentil protein as a novel foaming plant-based stabilizer is demonstrated in food and non-food applications where stable, long-life foams are required.

Liquid chromatography and mass spectrometry in food allergen detection

Food allergy is an important issue in the field of food safety because of the hazards for affected persons and the hygiene requirements and legal regulations imposed on the food industry. Consumer protection and law enforcement require suitable analytical techniques for the detection of allergens in foods. Immunological methods are currently preferred; however, confirmatory alternatives are needed. The determination of allergenic proteins by liquid chromatography and mass spectrometry has greatly advanced in recent years, and gel-free allergenomics is becoming a routinely used approach for the identification and quantitation of food allergens. The present review provides a brief overview of the principles of proteomic procedures, various chromatographic set ups, and mass spectrometry instrumentation used in allergenomics. A compendium of published liquid chromatography methods, proteomic analyses, typical marker peptides, and quantitative assays for 14 main allergy-causing foods is also included.

Subunit structure of glycinin and its molecular species based on RP-HPLC, gel electrophoresis and SEC studies

Glycinin and its molecular species (glycinin I and glycinin II) were separated and isolated. The number and kind of subunits of glycinin, glycinin I and glycinin II were determined. Studies were carried out under different experimental conditions using slab gel electrophoresis, size-exclusion chromatography and reversed-phase high performance liquid chromatography. Gel electrophoresis was done using both continuous and discontinuous system and under varying concentrations of resolving gel. In addition, the subunits were separated by reversed phase using gradient program. Glycinin and glycinin II were found to have 12 subunits each while glycinin I showed six subunits. Molecular weight and weight ratio in each case were also determined.

Protein quality, antigenicity, and antioxidant activity of soy-based foodstuffs

Commercial soy-based foodstuffs, including beverages ( n = 15), cow's milk supplemented with soy isoflavones ( n = 1), snacks ( n = 1), and biscuits ( n = 2), were analyzed to find any link between alterations in protein quality, safety (antigenicity), functionality (antioxidant activity), and food processing. Protein content was analyzed by the Kjeldhal method and available lysine by OPA assay. Chromatographic (RP-HPLC) and electrophoretic (SDS-PAGE) protein profiles were obtained to monitor modifications in the structure of soy allergens. The antigenicity was estimated by immunoblotting against soy total antibodies. Total phenol content was measured by Folin-Ciocalteu, while peroxyl radical scavenging activity of the sample was determined by ORAC FL assay. Protein content did not differ of those declared by the producers. Lysine availability was higher in liquid soy beverages compared to that in other soy foodstuffs studied here. 7S and 11S soy allergens were detected by RP-HPLC and SDS-PAGE, respectively. Both data indicated changes in soy protein patterns due to processing of instant powdered soymilk, soy snacks, and biscuits. Immunoblotting assay showed modifications in the antigenic response of these foodstuffs based on soy, suggesting that their processing had altered the structure of soy allergens. RP-HPLC, SDS-PAGE, and immunoblotting resulted in adequate analytical approaches for detecting changes in protein structure due to processing and adulteration. Protein quality, antigenicity, and antioxidant activity of soy products can be affected as a function of the intensity of the thermal processing.

Perfusion reversed-phase high-performance liquid chromatography/mass spectrometry analysis of intact soybean proteins for the characterization of soybean cultivars

Perfusion reversed-phase HPLC (RP-HPLC)-electrospray mass spectrometry (ESI-MS) was employed for the characterization of soybean cultivars through the analysis of intact soybean proteins. The similarities and differences between yellow soybeans (the most usual soybeans) and other beans with different pigmentation (green, red, and black) commercialized as soybean were investigated. Red beans commercialized as azuki that are frequently sold as red soybean were also analyzed. Separation was carried out using a perfusion column at a flow-rate of 0.5 mL/min and a gradient elution. A step-by-step procedure was used for the optimization of the mass spectrometry parameters enabling the most sensitive detection. The method was applied to the analysis of the above-mentioned beans and the main soybean proteins (11S and 7S globulins) obtained by a fractionation procedure. MS spectra obtained from every peak in the beans and in their fractions were compared observing clear differences between yellow soybeans and the other beans with different pigmentation. The identification of some soybean proteins in yellow soybeans was also possible.

Characterization and differentiation of diverse transgenic and nontransgenic soybean varieties from CE protein profiles

Nowadays, soybeans are commercialized in a wide variety of colors and tones. Moreover, some pigmented seeds are being commercialized as soybeans while, on other occasions, these seeds are labeled as mung beans, azuki beans or soybean frijoles generating confusion on their identity. In this work, CE has been applied for the first time for the characterization and differentiation of different pigmented beans commercialized as soybeans. Other seeds commercialized as azuki, mung green soybeans or soybean frijoles were also analyzed. Borate buffer (at pH 8.5) containing 20% v/v ACN was used as the separation media and solution containing ACN/water (75:25 v/v) with 0.3% v/v acetic acid was used to solubilize the proteins from the samples. A 50 cm bare fused-silica capillary was employed for obtaining adequate separations in about 12 min. The CE protein pattern observed for yellow soybeans was different from that corresponding to green and red soybeans. The seeds commercialized as black soybean presented electropherograms identical or similar to those yielded by the yellow seeds with the exception of the sample labeled as black soybeans frijoles that presented a totally different pattern. In addition, CE protein profiles obtained for azuki and mung green soybeans were very similar to those corresponding to red soybeans and green soybeans, respectively. Finally, the CE method was also applied to differentiate transgenic and nontransgenic soybean varieties. Discriminant analysis, using several protein peak areas as variable, was used to successfully classify these samples.

Development of a perfusion ion-exchange chromatography method for the separation of soybean proteins and its application to cultivar characterization

A perfusion ion-exchange chromatography method has been designed, for the first time, for the separation of soybean proteins and its application to the characterization of soybean cultivars. For that purpose, the gradient, the mobile phase composition (buffer concentration, buffer pH, and elution salt), and the temperature were optimized. The method consisted of a two-step gradient (0% B for 2 min and from 0 to 50% B in 10 min) being mobile phase A a 2 0mM borate buffer (pH 9) and mobile phase B a 20 mM borate buffer (pH 9) containing 1M sodium chloride. The procedure used for the preparation of sample solutions was significantly simpler than that proposed by other authors and basically consisted of dissolving in water. This method enabled the separation of soybean proteins from a soybean protein isolate in 11 peaks in about 9 min. The method was used to separate soybean proteins in different commercial soybeans. In general, the 11 peaks yielded by the soybean protein isolate were also observed in the chromatograms of all soybeans. However, the area percentages of every peak in every soybean enabled the differentiation between soybeans. Moreover, the method was also used to separate soybean proteins in the proteic fractions obtained from every soybean. Multivariate methods were used for patterns recognition and the classification of samples.

High performance liquid chromatography and capillary electrophoresis in the analysis of soybean proteins and peptides in foodstuffs

The increasing interest in functional and healthy food products has promoted the use of soybean in the manufacture of foods for human consumption. Soybean basic products (soybeans, textured soybean, soybean flour, soybean protein concentrate and soybean protein isolate) as well as soybean derivatives (soybean dairy-like products, soybean drinks with fruits, meat analogues, etc.) are commercially available. In addition, due to the interesting nutritional and functional properties of soybean proteins, they are usually employed as ingredient in the elaboration of a large number of food products such as bakery or meat products among others. In spite of the good characteristics of soybean proteins, their addition to some products is forbidden or allowed up to a certain limit. Therefore, analytical methodologies to achieve the determination of soybean proteins in foods are necessary in order to make possible adequate quality control and to prove that legal regulations controlling their addition are accomplished. However, this is not an easy task due to the diversity and complexity of the food matrices and the technological treatments to which some of these foods are submitted during their elaboration. This article presents for the first time a comprehensive review on the analytical methodologies developed using HPLC and CE to characterize soybeans and to analyse soybean proteins in meals. Moreover, the use of HPLC and CE in the characterization of soybean protein fractions and their hydrolyzates, and a study of their relationships to nutritional, functional and biomedical properties are included. Finally, the application of proteomic methodologies in soybean food technology is also reviewed.

Simple and rapid characterization of soybean cultivars by perfusion reversed-phase HPLC: application to the estimation of the 11S and 7S globulin contents

A perfusion RP HPLC method enabling the separation of soybean proteins in an analysis time lower than 3 min has been used to obtain the chromatographic profiles of different soybean cultivars. The chromatograms obtained for each soybean variety presented clear differences that justified the potential use of this method for cultivar characterization. The area percentages obtained were employed as variables for cluster and principal components analysis of these soybeans. The application of these multivariate methods enabled the grouping of the soybeans in different categories. The protein fractions obtained from these soybeans by the application of a fractionation method were also analyzed. The chromatographic profiles obtained enabled the assignment of peaks to the main soybean proteins (7S and 11S globulins). These data were used for the estimation, for the first time, of the 7S and 11S globulin contents in soybean cultivars.

Development of a perfusion reversed-phase HPLC method for the separation of soybean and cereal (wheat, corn, and rice) proteins in binary mixtures. Application to the detection of soybean proteins in commercial bakery products

A perfusion reversed-phase HPLC method enabling the simultaneous separation of soybean and cereal (wheat, corn, and rice) proteins in commercial bakery products has been proposed for the first time. The method utilises an acetonitrile-water gradient containing an ion-pairing agent. Different ion-pairing agents were tried, 0.3% (v/v) acetic acid being observed to enable the separation of soybean from wheat, rice, and corn proteins while with 0.1% (v/v) trifluoroacetic acid only the separation of soybean and corn proteins was possible. Optimisation of the solubilisation conditions for proteins was achieved by testing different acetonitrile concentrations for the simultaneous extraction of soybean and cereal proteins: best recoveries were found with 25% (v/v) acetonitrile + 0.3% (v/v) acetic acid and with 40% (v/v) acetonitrile + 0.1% (v/v) trifluoroacetic acid. Chromatographic conditions such as gradient, temperature, and wavelength detection were also optimised. The method enabled the separation of soybean and cereal proteins in binary mixtures (soybean and wheat, soybean and corn, or soybean and rice proteins) in less than 5 minutes in a total analysis time of 20 min.

Characterization of beta-conglycinin and glycinin soy protein fractions from four selected soybean genotypes

The beta-conglycinin and glycinin fractions of soy protein were isolated from Macon, Ohio FG1, Enrei, and IL2 genotypes that were grown under the same environmental conditions. The soy protein fractions were evaluated to determine whether chemical composition and gel-forming properties were related. Amino acid analyses suggested that the hydrophobic residues may be the primary cause of differences in soy protein gel characteristics as the storage moduli increased with higher percentages of hydrophobic residues. Reversed-phase high-performance liquid chromatography profiles revealed variations in the composition of each fraction that corresponded to differences observed among the storage moduli. The gel-forming properties may be related to more than just protein content, such as the amount and type of amino acid in the fraction.

Determination by perfusion reversed-phase high-performance liquid chromatography of the soybean protein content of commercial soybean products prepared directly from whole soybeans

The use of soybean flour as external standard for the determination of soybean proteins in soybean products directly prepared from whole soybeans is investigated. For that purpose a perfusion reversed-phase high-performance liquid chromatography method consisting of a linear binary gradient acetonitrile-water (both with 0.1% trifluoroacetic acid) in 3 min at a flow-rate of 3 ml/min, and a temperature of 60 degrees C is used. Samples dissolved in water are directly injected in the chromatographic system. The method is validated by evaluating detection limits, precision, and accuracy and applied to the quantitation of soybean proteins in soybean products directly prepared from whole soybeans.

Characterization of commercial soybean products by conventional and perfusion reversed-phase high-performance liquid chromatography and multivariate analysis

Conventional and perfusion reversed-phase high-performance liquid chromatography are used to characterize commercial soybean products for human consumption. For this purpose, previously optimized methods of conventional and perfusion chromatography applied to the separation of soybean proteins are employed. Sixty different samples corresponding to 26 different trademarks of soybean products [soybean protein isolate, soybean flour, textured soybean, soybean milks (liquid and powdered), and soybean infant formulas] are analyzed. Characterization of soybean products is carried out on the basis of their protein profiles obtained by both chromatographic methods. Data obtained are processed using multivariate methods such as principal components and discriminant analysis. Perfusion chromatography enables a further and faster characterization of commercial soybean products than conventional chromatography, of great value in the quality control of this kind of product.

A reversed-phase high-performance liquid chromatographic method for the determination of soya bean proteins in bovine milks

A reversed-phase high-performance liquid chromatographic method was designed for the quantitation of soya bean proteins in bovine milks. The method consisted of a linear binary gradient, acetonitrile-water-0.1% trifluoroacetic acid, at a flow rate of 1 mL/min and a temperature of 50 degrees C which resulted in a separation time for soya bean proteins of 11 min. Calibration by the external standard method using a soya bean protein isolate as standard was employed, and the method was validated by evaluating precision, accuracy, and robustness. This method was shown to be useful for the analysis of soya bean proteins in bovine milks spiked with soya bean protein isolate; soya bean protein concentrations of approximately 13 microg/g of bovine milk could be detected by using the optimized method. The results obtained for some of the bovine milks were compared with those obtained by the method of standard additions.

Analysis of bovine whey proteins in soybean dairy-like products by capillary electrophoresis

The simultaneous separation of bovine whey proteins [alpha-lactalbumin and beta-lactoglobulin (A+B)] and soybean proteins was performed, for the first time, by capillary electrophoresis. Different experimental conditions were tested. The most suitable consisted of 0.050 M phosphate buffer (pH 8) with 1 M urea and 1.2 mg/ml methylhydroxyethylcellulose, UV detection at 280 nm, 15 kV applied voltage, and 30 degrees C temperature. Quantitation of bovine whey proteins in a commercial powdered soybean milk manufactured by adding bovine whey to its formulation was performed using the calibration method of the external standard. Direct injection of a solution of the powdered soybean milk only enabled quantitation of alpha-lactalbumin in the commercial sample. Detection of beta-lactoglobulin (A+B) required acid precipitation of the solution of the sample in order to concentrate bovine whey proteins in the supernatant prior to the analysis of this protein in the whey obtained. Since alpha-lactalbumin could also be quantitated from the injection of the whey, the simultaneous determination of alpha-lactalbumin and beta-lactoglobulin (A+B) was possible upon acid precipitation of the powdered soybean milk solution. Detection limits obtained were 14 microg/g sol. for alpha-lactalbumin and 52 microg/g sol. for beta-lactoglobulin (A+B) which represent protein concentrations about 60 microg/100 g sample for alpha-lactalbumin and 100 microg/100 g sample for beta-lactoglobulin (A+B).

Characterization and quantitation of soybean proteins in commercial soybean products by capillary electrophoresis

Capillary electrophoresis was applied for the first time to determine soybean proteins in commercial soybean products. The most suitable conditions for the analysis of these products in less than 7 min were 0.05 M phosphate buffer (pH 8) with 1 M urea; detection wavelength, 254 nm; applied voltage, 20 kV; and temperature, 30 degrees C. Quantitation of soybean proteins was achieved using referenced conditions by means of the method of standard additions, using as standard a soybean protein isolate. This method was validated and applied to the quantitation of soybean proteins in commercial products derived from soybean protein isolate and soybean seeds.

Composition and characterization of soyabean and related products

Soyabean contains about 48 to 50% proteins. Among these, storage proteins are predominant. 7S and 11S globulins are two storage proteins that constitute 80% of the total protein content in soyabean. Moreover, there are other less abundant storage proteins such as 2S, 9S, and 15S globulins. In addition to globulins, enzymes, protease inhibitors (Kunitz and Bowman-Birk), lectin, and other complete the soya protein content. Different methods exist to characterize soya proteins. These methods involve (1) an isolation of proteins from soya commercial products and (2) the use of analytical techniques for protein determination. Soya proteins may interact with other soya components such as minerals, phytic acid, ascorbic acid, and fiber. These interactions, which depend on soya processing and treatment, can decrease the bioavailability of minerals and proteins. Swelling, solubility, viscosity, and capacity to form a gel, an emulsion, or a foam are the main functional properties of soyabean. They are responsible for the wide use of soya in industrial processes.

Simultaneous separation of soya bean and animal whey proteins by reversed-phase high-performance liquid chromatography. Quantitative analysis in edible samples

A reversed-phase high-performance liquid chromatography method was developed successfully for the simultaneous and rapid separation of the main soya bean proteins (globulins) and animal whey proteins (alpha-lactalbumin and beta-lactoglobulin). This method consisted of a linear gradient of two mobile phases (0.1% trifluoroacetic acid in water and 0.1% trifluoroacetic acid in acetonitrile). For the first time, soya bean globulins were separated from animal whey proteins. The analysis time for this separation was 20 min, eluting soya bean globulins in the first 10 min. The method was applied to quantify soya bean proteins in soya bean commercial milks with the possibility of detecting the presence of animal whey proteins. Adulteration of a powdered soya bean milk by animal whey proteins was detected. The possibility of detecting the presence of soya bean proteins in animal milks was also studied.

Rapid separation of soybean globulins by reversed-phase high-performance liquid chromatography

A rapid separation of the main soybean proteins (7S and 11S globulins) was carried out by reversed-phase high-performance liquid chromatography. For this purpose, a linear binary gradient acetonitrile--water--0.1% trifluoroacetic acid, at a flow-rate of 1 ml/min and 50 degrees C temperature was designed. Under the experimental conditions of this work, it was possible to separate five peaks corresponding to the globulins from a soybean protein isolate in 9 min. The characterization of soybean proteins was accomplished by analyzing the 7S and 11S purified fractions obtained from a soybean protein isolate. The method was applied to the separation of soybean proteins from commercial foodstuffs: soybean flour, textured soybean and soybean milks.