Isolation and characterization of protein fractions from deoiled rice bran

Rice bran contains underutilised protein materials. Sequential extraction of rice bran protein (RBP) from defatted rice bran was conducted based on the differences in their solubility. Three extraction methods were investigated. Method 1 involved the isoelectric and acetone precipitation using water, 50 g kg⁻¹ NaCl, 0.02 mol L⁻¹ NaOH and 70% ethanol as extracting solvents for albumin (pH 4.1), globulin (pH 4.3), glutelin (pH 4.8) and prolamin, respectively. Method 2 adopted dialysis and sequential extraction was carried out with 20 g kg⁻¹ NaCl, 70% ethanol, 0.1 mol L⁻¹ acetic acid and 0.1 mol L⁻¹ NaOH solution as extracting solvents. Method 3 combined dialysis, isoelectric and acetone precipitation for the extraction. Based on the yields and data obtained from sodium dodecyl sulphate polyacrylamide gel electrophoresis, size-exclusion chromatography and differential scanning calorimetry, method 3 was chosen for the isolation and characterization of RBPs. Rice bran protein fraction (RBPF)—albumin, globulin, glutelin and prolamin were obtained in good yields. Denaturation temperature and enthalpy values of denaturation of RBPF vary. Highest phytate content was found in albumin and lowest in prolamin. The highest antioxidative and hemagglutinating activities were observed in albumin.     

Characterization of low-phytate soy protein isolates produced by membrane technologies

Soy protein isolates (SPI) produced by combining electro-acidification and tangential ultrafiltration/diafiltration (UF/DF) (pH 6), were compared in terms of composition and proteins solubility with isolates produced by UF/DF (pH 9) and isoelectric precipitation (pH 4.5). Mineral and phosphorus (phytic acid) removal was enhanced for the SPI pH 6. Whey-like proteins (M.W. < 66 kDa) were also found in higher concentration for the SPI produced by membrane technologies. This difference in composition resulted in improved solubility characteristics for the SPI pH 6 by as high as 25% and 60%, when compared to the SPI pH 4.5 and SPI pH 9, respectively. Improvement in solubility was most important between pH 2 and 4.5. The quantity of H⁺ ions added to the soy protein extract (SPE) and SPI to reduce the pH from 9 to 4.5, during solubility measurement, was related to the degree of proteins aggregation, as determined by size-exclusion high-performance liquid chromatography, and at a lesser extent to their phytic acid content. For the pH range of 4.5 to 2, the degree of proteins aggregation alone determines the quantity of H⁺ ions added.Industrial relevanceSoy protein production is one of the major agricultural sectors of significant importance to North America and soy proteins represent 69% of global plant protein consumption in the world. Soy protein concentrates and isolates are produced at the industrial scale by isoelectric precipitation. This process has a high productivity, however, it also generates large volumes of effluent. The final products also have significant contents of minerals and of phytic acid, the latter of which is well known to decrease the proteins and minerals adsorption in the intestine.We were the first group to combine bipolar membrane electrodialysis (BMED) and ultrafiltration (UF) (dead-end) for the production of soy protein concentrates (Mondor, Ippersiel, Lamarche & Boye, 2004). The new approach resulted in a significant decrease of the volumes of effluent due to the use of BMED to adjust the pH of the extract prior to UF and by improving the protein washing step using diafiltration (DF). It was also shown that for the pH range 6–9, minerals and phytic acid removal was improved with a decrease in pH. In this work, we present the characteristics of a soy protein isolate with a low phytic acid/protein ratio (SPI pH 6) produced by BMED and tangential flow UF/DF applying an optimal VCR5, re-VCR 5 sequence at pH 6. The SPI pH 6 shows an improved solubility by as high as 25% and 60%, when compared to an isolate produced by isoelectric precipitation at pH 4.5 and to one produced by UF/DF at pH 9, respectively. Improvement in solubility was most important between pH 2 and 4.5 indicating that this isolate could be considered as a valuable ingredient for the formulation of fruit juice beverages or power juices, considering that the pH of these liquid food products is around 3.5.     

Degradation kinetics of ergosterol in tomato paste serum

Thermal degradation of ergosterol in tomato paste serum was studied at different pH (4.5, 4.3, 3.9, 3.7 and 3.5,) and heating periods (0, 10, 20, 30 and 50 min) over the temperature range of 70 to 95 °C. Analysis of kinetic data suggested a first-order reaction for the degradation of ergosterol with the half-lives of 301.4–36.7, 239.0–33.7, 203.9–29.6, 113.6–29.8 and 83.5–23.7 min for 4.5, 4.3, 3.9, 3.7 and 3.5 pH samples, respectively, between 70 and 95 °C. Temperature dependence of reaction was described by the Arrhenius relationship. Activation energies for 4.5, 4.3, 3.9, 3.7 and 3.5 pH samples were found 20.57, 19.62, 19.07, 12.41 and 11.08 kcal mol⁻¹, respectively, between 70 and 95 °C.     

Optimisation of mild-acidic protein extraction from defatted sunflower (Helianthus annuus L.) meal

For protein isolation from defatted sunflower meal, mild-acidic extraction was investigated to minimise concomitant oxidation and polymerisation of phenolic compounds and their irreversible binding to proteins. Because of the impaired solubility of sunflower proteins at low pH, the potential of sodium chloride (NaCl) to improve protein extractability was firstly screened for pH 2–11. Increasing NaCl concentrations of the aqueous solvent (c_NaCl) up to 2.8 mol/L enhanced the relative protein yield to almost 80% at ambient temperature and pH 5.6–7.4. As to improved protein recovery at minimal interactions with phenolic acids, the concerted effects of pH (3.2–7.4), c_NaCl (1–3 mol/L), temperature (T, 15–45 °C), and meal-to-solvent ratio (MSR, 0.03 and 0.05 g/mL) on the protein concentration of the extract (c_PE) and the relative protein yield (RPY) were examined, using response surface methodology (RSM). Aside from the prevailing influence of pH value and salt concentration, elevated temperature slightly enhanced protein extraction, whereas MSR mainly influenced c_PE, but hardly RPY. Calculated models proved suitable for the evaluation of extraction processes and the prediction of optimum conditions in terms of high protein yields at the lowest pH possible. Extraction at pH 6.0 was shown to be an appropriate compromise yielding 76–83% of the meal protein, depending on the constraints given. With elevated NaCl concentrations compensating for unfavourable pH conditions, mild-acidic extraction was found to be suitable for the recovery of high-quality sunflower protein in terms of light-coloured protein isolates.     

Mechanical Properties of Ovalbumin Gels Formed at Different Conditions of Concentration,Ionic Strength,pH, and Aging Time

Ovalbumin gels were prepared by heat treatment at constant pH and ionic forces. Ovalbumins are widely utilized as emulsifying or binding agents. However, due to their protein origin, mechanical properties of ovalbumins are enclosed in a wide range of rheological responses depending on concentration, ionic strength, pH, and aging time. The objective of this work was to study the effect of processing conditions (pH, ionic strength, and protein content) on the textural attributes of an ovalbumin protein system by means of uniaxial compression. Gels were prepared by dispersing proteins (purity 98%) (8.3–12.5% w/w) until complete dissolution in deionized water at 90°C by 45 min, pH (6.3–9.1) was adjusted using citric acid, and the ionic strength (0–100 mM of NaCl) was adjusted using NaCl. The storage of gels was done at 63°C (24–168 h). The rheological tests of gels were done by uniaxial compression. A rupture force peak was observed at high protein content together with an increase in the Young’s modulus. At fixed conditions of ion content (NaCl 50 mM) and pH of 7, the gels presented a maximum in fracture force and Young's modulus after 7 days of storage. The addition of minimum amount of citric acid increases the stability of ovalbumin gels. This information is useful to ensure that the final product will remain stable during storage time at longer shelf lives.     

Supercritical CO<Subscript>2</Subscript> extraction of <Emphasis Type="Italic">Alkanna</Emphasis> species and investigating functional characteristics of alkannin-enriched yoghurt during storage

Alkannin is a potent pharmaceutical substance with a wide spectrum of biological activities. In the scope of this study, supercritical CO₂ extraction and sonication with hexane were applied to various Alkanna species, which were then subjected to hydrolysis. Total alkannins were quantified by HPLC/DAD and incorporated into yoghurt. Viscosities, pH values and microbial analyses were reported at 7 days of intervals for 21 days of storage. A. tinctoria possessed the highest amounts of alkannins and total phenols (686.3 mg GAE/g extract). The results revealed no significant changes in pH values (4.1–4.0), viable counts of Streptococcus salivarius ssp. thermophilus (80–150 × 10⁶ cfu g⁻¹) and slightly lower viscosities of enriched yoghurts (8,250–6,750 cPs) compared with the control (4.15–4.0; 110–105 × 10⁶ cfu g⁻¹; 12,600–11,310 cPs) during storage. However, viable counts of Lactobacillus delbrueckii ssp. bulgaricus of enriched yoghurts (87 × 10³ cfu g⁻¹) were much better than the control (191 × 10³ cfu g⁻¹), indicating a significant decrease in post acidification and generation of bitter peptides. Among the species investigated, A. tinctoria is the most promising source, obtained at higher yields via supercritical fluid extraction technology as a green alternative to solvent extraction and thus can be utilized at industrial scale in order to develop yoghurt products with improved health benefits.     

Interactions between isoflavones and soybean proteins: Applications in soybean-protein-isolate production

The effects of several modifications to soybean protein isolate (SPI) production on genistein series composition and content were analyzed. Combined variations of protein extraction pH and protein precipitation pH revealed that the maximum content of total genistein series was obtained with protein extraction at pH 8.0 and protein precipitation at pH 3.5. When protein extraction was carried out at pH 11.0, the saponification of malonylgenistin, resulting in genistin production, led to a decrease in isoflavone content. This fact was attributed to the low affinity of genistin for β-conglycinin. Malonylgenistin exhibited a high level of association with both glycinin and β-conglycinin at precipitation conditions. When temperature was reduced from 20 to 0 °C during protein precipitation, the genistein series content increased if the β-glucosidase activity was inhibited. This increase was at the expense of glucosilated forms. The nature of the interaction between soybean proteins and malonylgenistein and genistin seemed to be - at least in part - enthalpic in nature. In particular, malonylgenistin at pH 3.5 establishes another kind of interaction with protein, besides enthalpic ones. Glycinin exhibited higher affinities for genistein series components than β-conglycinin, the interactions being more stable at acidic than at alkaline pHs.     

Characterisation of protein‐rich isolates and antioxidative phenolic extracts from pale and black brewers' spent grain

Protein‐enriched isolates and co‐product fractions were obtained from sheared, pale and black brewers' spent grain (BSG) using sequential aqueous and alkaline (110 mm NaOH) extraction, followed by isoelectric precipitation at pH 3.8. A recovery of 59% of the original pale BSG protein and 15% of the black BSG protein was obtained for the final isolates. Gel permeation HPLC (GP‐HPLC) revealed that 59% of the extracted pale BSG protein and only 6% of black BSG protein had a molecular mass >10 kDa. Glutamine/glutamate and proline were the most abundant amino acids present in both isolates. Analysis of four co‐product fractions obtained during fractionation from both pale and black BSG revealed the presence of phenolics, with higher concentrations in the black BSG extracts. These fractions possessed antioxidant and free radical scavenging activity when tested using the ferric reducing ability of plasma (0.16 ± 0.01 to 4.33 ± 0.11 mg Trolox equivalents g^?1 BSG dry weight) and diphenylpicrylhydrazyl (12.85 ± 1.16% to 59.50 ± 3.47% DPPH?_sc) assays, respectively. The protein‐enriched isolates and the phenolic‐rich extracts may find use as value‐added ingredients for incorporation into conventional and functional foods.     

Characterization and functional properties of watermelon (<Emphasis Type="Italic">Citrullus lanatus</Emphasis>) seed protein isolates and salt assisted protein concentrates

Watermelon (Citrullus lanatus) seed meal contains significant amount of extractable protein which can be used as nutritional and functional ingredients in food formulations. Alkali (0.1 M) and NaCl (0.5 M) were used to prepare protein isolates and concentrates from the defatted watermelon seed meals. Protein isolates reported protein yield of 35.15–38.27% and protein content (79.05–83.79%) which was significantly (p≤0.05) higher than the protein concentrates. SDS-PAGE of protein isolates and concentrates showed major polypeptides in the range of 74.72–110.42 kDa. Also, in vitro pepsin digestibility showed that most of the proteins were readily digested within 30 min of hydrolysis. Amino acids were dominated by arginine, aspartic, and glutamic acid. DSC results indicated that protein concentrates had significantly (p≤0.05) higher denaturation temperatures than protein isolates. The functional properties of concentrates in terms of solubility and surface properties were better than respective isolates. The results indicated that NaCl extracted proteins had comparatively better functional properties but their yield is significantly lower than respective protein isolates.     

Changes of Molecular Forces During Thermo-Gelling of Protein Isolated from PSE-Like Chicken Breast by Various Isoelectric Solubilization/Precipitation Extraction Strategies

Changes in protein intermolecular interactions during thermo-gelling were measured to compare the gelation properties of isoelectric solubilization/precipitation (ISP)-isolated protein extracted (solubilized at 3.5 and 11.0, precipitated at 5.5 and 6.2) from pale, soft, and exudative (PSE)-like chicken breast meat with raw meat paste. The solubility of both in water and salt (0.6 M NaCl) decreased significantly after ISP treatments. Protein profile analysis revealed that precipitation pH showed little influence on protein profile. Under pH 3.5 and pH 11.0 solubility conditions, the recovered protein at pH 6.2 showed significantly higher gel hardness than that at pH 5.5, which can be induced by hydrophobic change. Surface hydrophobicity (SH₀) and hydrophobic interactions at 25 °C presented similar results, indicating that the soluble protein at pH 11.0 exhibited a higher value after precipitation at pH 6.2 than that at pH 5.5, and the hydrophobicity of pH 3.5 isolates was higher than that of the pH 11.0 groups. However, the maximum hydrophobicity upon heating was inconsistent with initial tendencies. Given that the hydrophobic residues were exposed sufficiently during the ISP process, the ISP-treated proteins, particularly the samples extracted at pH 3.5, might be less susceptible to heat-induced exposure. The gelation behavior of the ISP-treated proteins had been modified on the basis of the intermolecular bonds during heating. In conclusion, the precipitation condition demonstrated excellent relevance for product development based on functionality.     

Partial Purification and Characterization of Extracellular Fructofuranosidase with Transfructosylating Activity from <Emphasis Type="Italic">Candida</Emphasis> sp.

The present work was carried out with the aim to investigate some properties of an extracellular fructofuranosidase enzyme, with high transfructosylating activity, from Candida sp. LEB-I3 (Laboratory of Bioprocess Engineering, Unicamp, Brazil). The enzyme was produced through fermentation, and after cell separation from the fermented medium, the enzyme was concentrated by ethanol precipitation and than purified by anion exchange chromatography. The enzyme exhibited both fructofuranosidase (FA) and fructosyltransferase (FTA) activities on a low and high sucrose concentration. With sucrose as the substrate, the data fitted the Michaellis–Menten model for FA, showing rather a substrate inhibitory shape for fructosyltransferase activity. The K _m and v _max values were shown to be 13.4 g L⁻¹ and 21.0 μmol mL⁻¹ min⁻¹ and 25.5 g L⁻¹ and 52.5 μmol mL⁻¹ min⁻¹ for FA and FTA activities, respectively. FTA presented an inhibitory factor K _i of 729.8 g L⁻¹. The optimum conditions for FA activity were found to be pH 3.25–3.5 and temperatures around 69 °C, while for FTA, the optimum condition were 65 °C (±2 °C) and pH 4.00 (±0.25). Both activities were very stable at temperatures below 60 °C, while for FA, the best stability occurred at pH 5.0 and for FTA at pH  4.5–5.0. Despite the strong fructofuranosidase activity, causing hydrolysis of the fructooligosaccharides (FOS), the high transfructosilating activity allows a high FOS production from sucrose (44%).     

Tocotrienol levels in sieving fraction extracts of brewer’s spent grain

Dried brewer’s spent grain (DBSG) is rich in tocotrienols (T3) and tocopherols (T) and can be used to produce a valuable oil with the serum cholesterol–lowering functions of lipid-soluble T3. The economic feasibility of extracting oil from DBSG (fat: 3.9–10.6% dry weight, dw) increases with increasing fat content of the feedstock. The objective of this research was to determine whether DBSG can be separated into fractions enriched in fat and T3 by milling and sieving and to characterize the fractions from sieves of different mesh sizes: 500, 800, 850, and 1,000 μm. Six different charges of DBSG were milled and sieved with different techniques ranging in scale from laboratory to industrial. The oil yield of DBSG sieving fractions >500 μm was consistently low (6.6–12.67% dw after Soxhlet extraction with 96% ethanol), as were the levels of T (77.4–185.6 mg/kg of extracted oil), T3 (181.9–538.8 mg/kg of extracted oil), and protein (14.38–25.73% dw). In contrast, oil yields of DBSG sieving fractions <500 μm were higher (12.98–18.09% dw after Soxhlet extraction with 96% ethanol), as were the concentrations of T (188.6–318.0 mg/kg of extracted oil), T3 (516.8–850.2 mg/kg of extracted oil), and protein (26.05–33.30% dw). Furthermore, oil yields were lower (8.24–12.39% dw) after Soxhlet extraction with n-hexane. Milled DBSG sieving fractions <500 μm thus appear to be a suitable feedstock for economical extraction of T3-rich oil and may be useful in developing markets for value-added brewing by-products.     

A Systematic Study on Extraction of Lipase Obtained by Solid-State Fermentation of Soybean Meal by a Newly Isolated Strain of <Emphasis Type="Italic">Penicillium</Emphasis> sp

This work aimed to assess the effect of some variables on the lipase extraction from the fermented medium in order to establish the experimental conditions that maximize the yield of the enzyme obtained from solid-state fermentation of soybean meal and a newly isolated strain of Penicillium sp. The experimental design technique was used to investigate the effect of relevant variables on lipase activity. The factors investigated were solvent pH (5.5–8.5), stirring rate (50–150 rpm), temperature (25–49 °C) and solid/liquid ratio (1:20–5:20). The effect of time of contact was evaluated in a kinetic study. Higher lipase activities in the extraction study were obtained using phosphate buffer 100 mM pH 8.5, at 25 °C, 150 rpm, and solid/liquid ratio of 1:20. Extraction studies showed that maximum activity (186 U/g) was obtained in 15 min of extraction.     

Enhancement of the functional properties of whey protein by conjugation with maltodextrin under dry‐heating conditions

Conjugation of whey protein isolate (WPI) and maltodextrin (MD, dextrose equivalent of 6) was achieved by dry‐heating at an initial pH of 7.0, at 60 °C and 79% relative humidity, with WPI: MD6 ratio of 1:1, for up to 24 h. Conjugation was achieved with limited development of colour and advanced Maillard products on 24 h of heating. Conjugation increased the protein solubility at pH 4.5, by 7.1–8.5%, compared to the unheated and heated WPI controls. Conjugation of WPI with MD6 enhanced the stability and retention of clarity in protein solutions heated at 85 °C for 10 min with 50 mM added NaCl.     

Coupling effects of preheating time and extraction medium pH on red radish anthocyanin yield,glucosinolate degradation and off‐odour removal

In this study, the effect of combined preheating time (2, 5, and 10 min) and extraction medium pH (2.5, 3.5, and 4.5) on total monomeric anthocyanin yield, and removal of off‐odour in red radish anthocyanins were evaluated. The tentative anthocyanin identification showed twelve pelargonidin anthocyanins, and only nine were identified in samples preheated for 10 min. Sample preheated for 10 min and extracted at pH 4.5 showed lower the anthocyanin yield (98.02 mg/100 g, FW), lighter colour and higher percentage polymeric colour compared with that preheated for 2 min and extracted at pH 2.5. However, prolonged preheating time (10 min) significantly reduced myrosinase enzyme activity by 73%. Additionally, results showed that preheating time and extraction medium pH have negative and significant effect on the total monomeric anthocyanin yield, while they showed positive and negative significant effect on the total glucosinolate degradation. Furthermore, the sensory evaluation results revealed no significant difference in radish odour for samples preheated for 2 and 5 min followed by anthocyanin extraction in pH 2.5 medium. It might therefore be concluded that the combination of moderated preheating treatment time (≤5 min) and lower extraction medium pH could be effective to reduce the off‐odour characteristics and maintaining high yield and stable red radish pigment.     

Influence of pH Shift on Functional Properties of Protein Isolated of Tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>) Muscles and of Soy Protein Isolate

The physicofunctional and chemical properties of acid-aided protein isolate (AcPi), alkaline-aided protein isolate (AlPi) and soy protein isolate (SPI) prepared from tilapia muscle and defatted soy flour as a function of pH and/or NaCl concentration were investigated. Both acid- and alkali-aided processes lead to significant recoveries (P < 0.05) of proteins with substantial reduction of lipids in AlPi (0.81%) and AcPi (0.96%), the lowest for SPI (0.336%) facilitated by the processing method and sample used. There is greater lipid reduction at alkali pH, effective removal of impurities such as bones and scales, indicated by percentage ash (AcPi, 4.53%; AlPi, 3.75% and SPI, 3.51%). No major difference noted in sodium dodecyl sulphate polyacrylamide gel electrophoresis protein bands (14.4–97.4 kDa) possibly representing partial hydrolysis of myosin. Solubility was the highest at pH 3.0 and 11.0 and the lowest at isoelectric point with foam capacity showing similarity at varying pH. The addition of NaCl improved foam stability, possibly due to the increased solubility and surface activity of the soluble protein. On the whole, AcPi, AlPi and SPI manifested lower solubility and foamability at pH 4.0 and 5.0. AlPi exhibited appreciable levels of solubility, emulsion capacity, oil-holding capacity, viscosity and whiteness, whereas SPI had appreciable water-holding capacity. AcPi, AlPi and SPI have excellent relevance for product development based on their functionality.     

Determination of Anthraquinone Derivatives in Chang-Qing Tea by Using Cloud-Point Extraction and High-Performance Liquid Chromatography

In this paper, a cloud-point extraction method was developed for the determination of five anthraquinone derivatives in Chang-Qing tea by high-performance liquid chromatography. The optimum conditions for micelle extraction were obtained as follows—15% (w/v) Genapol X-080 as extractant, pH 3.5, liquid/solid ratio 80, and extraction time, 40 min. For cloud point preconcentration, 20% (w/v) NaCl was added, and the solution was incubated at 55 °C for 30 min. The detection limits for the five anthraquinone derivatives were in the range of 0.55–3.30 ng ml⁻¹. Average recoveries for the anthraquinone derivatives at three spiked levels were in the range of 84.3–104.1%. Relative standard deviations for six replicate determinations of Chang-Qing tea sample were below 2.39. The established method has been successfully applied to the determination of anthraquinone derivatives in Chang-Qing tea products from three different manufacturers.     

Emulsifying and foaming properties of Phaseolus vulgaris and coccineus proteins

Protein isolates from two Phaseolus cultivars, common bean (Phaseolus vulgaris L.) and scarlet runner bean (Phaseolus coccineus L.), were prepared by wet extraction methods (isoelectric precipitation – 4000 rpm, ultrafiltration, extraction with NaCl 2%, and isoelectric precipitation – 9900 rpm). The protein isolates were characterized by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and then evaluated for their solubility. The emulsion stability of emulsions produced at pH 7.0 and 5.5 with 1% or 2% or 3% w/v protein isolate was evaluated by average droplet size diameter, viscosity and creaming measurements. Emulsions with 1% protein content were unstable through storage. Emulsions with 3% w/v protein isolate concentration, extracted by ultrafiltration at pH 5.5 from both cultivars, were flocculated; this was more pronounced for coccineus isolates. The foaming properties, for the respective foams, were investigated. Foams with 1% w/v protein showed little foaming ability Ultrafiltration isolates produced more foam, which was especially stable at pH 5.5.     

Preparation of canola protein materials using membrane technology and evaluation of meals functional properties

Suitable conditions for the extraction and precipitation of proteins from Iranian canola (Brassica napus, cv. Quantum, PF, and Hyola) meals were determined using a membrane-based process which consisted of extraction of hexane-defatted canola meals at pH 9.5–12.0 and precipitation, at pH values between 3.5 and 7.5, to recover a precipitated protein isolate (PPI). Acid soluble protein isolate (SPI) was then prepared by ultrafiltration (UF) followed by diafiltration (DF) and drying. The highest protein yield was obtained by alkaline extraction at pH 12.0 with all meals investigated. The maximum yield of precipitated protein was observed at pH values between 4.5 and 5.5, depending on variety and dehulling treatment. Almost 90% of the proteins were recovered in three products: PPI and SPI containing (81–98% protein, N*6.25), and the meal residue (35% protein). The glucosinolate content of all meals tested and their protein products was low, and in some cases they were below the detection limit of glucosinolates. Both isolates were low in phytic acid. Some functional properties (protein dispersibility index, water absorption, fat absorption, emulsifying activity, and foaming properties) were evaluated. Iranian canola meals were compared with soybean meal in terms of functional properties. All canola meals tested showed a high PDI and WA, and were superior to soybean meal in fat absorption, emulsifying activity and foaming properties.     

Extractability and functional properties of some legume proteins isolated by three different methods

The extraction of protein from the flour of three grain legumes (faba beans, chick peas and fenugreek) was investigated using three different methods. Three protein preparations were made: by alkaline extraction and precipitation at isoelectric pH (protein isoelectric precipitate, PIP); extraction with 0.5 M sodium chloride solution and precipitation by ionic strength reduction (protein micellar mass, PMM); extraction in aqueous or saline solution in the presence of pepsin or pancreatin (partially hydrolysed protein preparation, PHP). Two of the protein isolates had higher values of water absorption and fat absorption compared to their corresponding parent flours, with fenugreek being the exception. Oil emulsification of the isolates was in the descending order: PMM, PHP and PIP. The PHP isolate had the highest nitrogen solubility index (NSI) values at pH 2.4 followed by PMM at pH 5.7–6.4 and finally PIP at pH 4.5–5.5.