Heat Induced Gelation of Pea (Pisum sativum) Mixed Globulins, Vicilin and Legumin

Mixed globulins (MG) were extracted from ground dry peas (Pisum sativum, B-160) with 0.5M NaCl, 50 mM potassium phosphate, pH 7.2, and isolated by precipitation at pH 4.5. Crude vicilin and legumin were fractionated from the MG by dialysis against 0.2M NaCl, pH 4.8, and centrifugation, then further purified using DEAE-cellulose chromatography. Conditions for maximum gel hardness of heat induced MG gel, as determined with an Instron Universal Testing Machine, were heating for 20 min at pH 7.1 at 87°C. Purified vicilin, but not legumin, formed heat induced gels. The relationship was linear between protein (globulin) concentration and log gel hardness. At all protein concentrations studied, as proportion of legumin decreased, gel hardness increased.     

Preparation of transparent pea protein gels: a comparison of isolation procedures

Two commercially viable procedures for the preparation of protein fractions from pea flour are described and discussed. These fractions form thermally induced transparent gels at acid pH and are composed of the globulins, vicilin and legumin, identified by electrophoresis and differential scanning calorimetry. The gels have clarities that allow their use as vegetarian substitutes for gelatin and additionally show thermal stabilities suitable for applications in hot products. The influence of other food ingredients (salt, sugar and vegetable oil) on gel clarity is also investigated.     

不同酶类改性对大豆分离蛋白功能性质的影响

大豆分离蛋白的可控降解可以显著改善其乳化性和起泡性,分别选用来自动物、植物和微生物的胰蛋白酶、木瓜蛋白酶和米曲蛋白酶对大豆分离蛋白进行水解,对其水解程度与乳化性、起泡性和溶解性的关系进行研究。     

Extrusion Texturization of Air-Classified Pea Protein

Air-classified pea protein was texturized using a twin-screw extruder. The effects of moisture, screw speed and barrel temperature on the physical, functional and nutritional characteristics of texturized pea protein were investigated. Increased dough moisture increased product bulk density (BD) and available lysine (LYS) of texturized pea products, but decreased water-holding capacity (WHC) and in vitro protein digestibility (DIG). Raising the screw speed reduced BD and LYS of texturized pea protein, but increased WHC and DIG. Bulk density and LYS decreased as barrel temperature was increased, whereas WHC and DIG increased. Texturized pea protein resembled commercial texturized soy products with respect to most physical and functional properties.     

大豆分离蛋白及其制取

综述了大豆分离蛋白的特性和生产现状 ,找出了我国大豆分离蛋白生产与国外先进技术的差距 ,比较了四种大豆分离蛋白的提取方法 ,对大豆分离蛋白的研究和发展方向提出展望     

豌豆粉丝厂废水中蛋白质的提取和性质研究

本论文以豌豆粉丝厂废水中的蛋白为原料提取豌豆分离蛋白,通过对提取工艺进行研究,确定了在pH12.0,固液比1∶20(g/mL),30℃下提取30min的提取条件,提取率达到62.25%。氨基酸分析结果表明,所提豌豆分离蛋白(PPI)氨基酸没有遭到破坏,营养价值较高。通过对PPI功能性质研究发现,除了吸水吸油性外,PPI的乳化性、乳化稳定性、起泡性都和大豆分离蛋白(SPI)接近。由此可见,PPI可以作为SPI的替代品应用于食品,具有很大的实用价值。采用DSC研究了PPI的热力学性质,在87.67℃(7S)和104.28℃(11S)有两个峰,这可能是在碱溶酸沉过程中,蛋白结构发生了一定变化造成的。      

大豆分离蛋白改性对其功能性质影响

大豆分离蛋白是大豆蛋白最为精制形式,广泛应用于食品工业,并在不同产品中表现出不同功能。该文综述近年来大豆分离蛋白物理、化学、酶法及基因工程改性对其功能性质影响,经不同方式改性可产生合适功能性质,从而拓宽大豆分离蛋白在食品工业中应用。     

大豆分离蛋白的乙酰化

本文通过对乙酰化改性大豆分离蛋白(SPI)影响因素的研究,确定了乙酰化大豆分离蛋白(A-SPI)的最佳工艺条件.在这个条件下生产的 SPI 有较好的功能性质,提高了在 pH 值4.5～7范围的溶解性,降低了凝胶强度.同时,乙酰化不会改变大豆蛋白的营养价值和产品质量.研究结果表明,本实验的数据是可靠的,效果是较好的,达到了预定的目的.     

Functional properties of protein hydrolysates from pea (Pisum sativum,L) seeds

The aim of this study was to investigate the effects of partial enzymatic hydrolysis on functional properties of two different pea protein isolates obtained from two pea genotypes, Maja and L1. Papain and commercial protease (Streptomyces griseus protease) were used for protein modification. Solubility, emulsifying and foaming properties were estimated at four different pH values (3.0, 5.0, 7.0 and 8.0). Papain increased solubility of L1 pea protein isolate at pH 3.0, 5.0 and 8.0, emulsifying properties and foaming capacity at all pH values. Otherwise, papain increased solubility of Maja pea protein isolate only at pH 8.0. This pea protein isolate modified with both enzymes formed emulsions with improved stability at lower pH (3.0, 5.0). The commercial protease‐prepared pea protein isolates showed generally low solubility and different emulsifying and foaming properties. Proper selection of enzyme, conditions of hydrolysis and genotypes could result in production of pea protein isolates with desirable functional properties.     

Solubility of commercial milk protein concentrates and milk protein isolates

High-protein milk protein concentrate (MPC) and milk protein isolate (MPI) powders may have lower solubility than low-protein MPC powders, but information is limited on MPC solubility. Our objectives in this study were to (1) characterize the solubility of commercially available powder types with differing protein contents such as MPC40, MPC80, and MPI obtained from various manufacturers (sources), and (2) determine if such differences could be associated with differences in mineral, protein composition, and conformational changes of the powders. To examine possible predictors of solubility as measured by percent suspension stability (%SS), mineral analysis, Fourier transform infrared (FTIR) spectroscopy, and quantitative protein analysis by HPLC was performed. After accounting for overall differences between powder types, %SS was found to be strongly associated with the calcium, magnesium, phosphorus, and sodium content of the powders. The FTIR score plots were in agreement with %SS results. A principal component analysis of FTIR spectra clustered the highly soluble MPC40 separately from the rest of samples. Furthermore, 2 highly soluble MPI samples were clustered separately from the rest of the MPC80 and MPI samples. We found that the 900 to 1,200 cm⁻¹ region exhibited the highest discriminating power, with dominant bands at 1,173 and 968 cm⁻¹, associated with phosphate vibrations. The 2 highly soluble MPI powders were observed to have lower κ-casein and α-_S1-casein contents and slightly higher whey protein contents than the other powders. The differences in the solubility of MPC and MPI were associated with a difference in mineral composition, which may be attributed to differences in processing conditions. Additional studies on the role of minerals composition on MPC80 solubility are warranted. Such a study would provide a greater understanding of factors associated with differences in solubility and can provide insight on methods to improve solubility of high-protein milk protein concentrates.     

Solubility properties of barley flour,protein isolates and hydrolysates

Protein solubility properties of barley flours (BF), barley protein isolates (BPI) and barley protein hydrolysates (BPH) were determined as a function of pH and NaCI concentration. BPIs were produced from both hulled (BPI-1 and BPI-3) and hull-less (BPI-2 and BPI-4) barley flours. Sodium metabisulphite (BPI-1 and BPI-2) or L-cysteine (BPI-3 and BPI-4) were included in the extraction procedure. BPI-4 was hydrolyzed with Alcalase in order to produce hydrolysates of 3% (BPH-1) and 6% (BPH-2) degree of hydrolysis. Electrophoretic properties of BFs, BPIs and BPHs were examined by SDS-PAGE. The results showed that solubility properties were affected by the changes of pH and ionic strength of the medium in all samples. The solubility properties of barley proteins were especially higher in the strong acidic and basic pH regions. Solubilities of BPI-1 and BPI-2 in distilled water were lower than those of BPI-3 and BPI-4. The lowest solubility was observed around the isoelectric points of BFs and BPIs. SDS-PAGE provided significant information about the monitoring of limited protein hydrolysis that produced large quantities of low molecular weight barley protein fragments with the Alcalase treatment. The solubility properties of BPHs around the isoelectric point were increased as a result of the limited hydrolysis.     

Effect of extraction conditions on composition,surface activity and rheological properties of protein isolates from flaxseed (Linum usitativissimum L)

Flaxseed protein isolates were prepared by micellisation (FM) and isoeletric precipitation (FI). The influence of preparation conditions on composition and functional properties was investigated. Contents of 0.6% phytic acid and 2.3% pentosans were found for FI, whereas FM was almost phytic acid‐free and had a low content of pentosans (0.6%). Chromatography and electrophoresis identified the 11S globulin (linin) as the main protein fraction in both isolates. Protein solubility, water‐ and oil‐binding capacities, emulsification and rheological properties of dispersions and gels were measured at pH 8 and 3. For the latter, interactions of protein with phytic acid and pentosans are highly probable. FI possesses a lower solubility (about 40–50%) and an overall higher water‐binding capacity than FM. For FI dispersions a higher storage modulus G′ than loss modulus G″ was measured, clearly pointing to the formation of protein networks. Moreover, FI formed stronger gels than FM (G′ about fivefold). The emulsifying activity, however, was distinctly lower for FI. These results point to enhanced complexation and aggregation of the isoelectric‐precipitated protein isolate. © 2002 Society of Chemical Industry     

胡麻分离蛋白提取工艺研究

为促进胡麻分离蛋白在食品工业中应用,采用碱溶酸沉原理研究胡麻分离蛋白提取工艺。分别讨论料液比、浸提液pH值、浸提温度和时间等条件对蛋白提取率影响,确定最佳提取条件为:料液比1:13、碱提液pH值9.5、时间60、温度60℃,在此条件下,胡麻分离蛋白提取率为42%,纯度达89.37%。     

Influence of temperature,pH and ionic strength on the production of isoflavone-rich soy protein isolates

Soy protein isolates (SPI) may present different isoflavone profiles and contents, depending on processing conditions. In the present work, seven different SPI, resulting from changes in the processing steps, were obtained. The best parameters for obtaining isoflavone-richer SPI were: extraction at pH 9 and temperature of 55 °C, acid precipitation performed at pH 4.5, acid-washing of the precipitate and mild centrifugation conditions for the separation of acid-precipitated proteins. Isoflavones were soluble in aqueous solution in the pH range 2–10 (73–93% of the amount solubilized in 80% methanol). The profile of isoflavones was dependent on the temperature used for the aqueous extraction. Temperatures below 50 °C caused hydrolysis of β-glucosides with increase of aglucones, by endogenous β-glucosidase activity.     

Structure,physicochemical, and functional properties of protein isolates and major fractions from cumin (Cuminum cyminum) seeds

In this study, cumin protein isolates (CPI) and major protein fractions were extracted and separated from cumin seeds, their structure, physicochemical, and functional properties were investigated. Albumin (62.29%) and glutelin (25.16%) were the predominant protein fractions of cumin seeds. Glutamic acid (Glu) and aspartic acid (Asp) were the major amino acids of cumin proteins, whereas more hydrophobic and aromatic amino acids were predominantly found in chickpea protein isolates. Electrophoresis profiles indicated that CPI have more disulphide bonds than major protein fractions. The intrinsic fluorescence data revealed that glutelin displayed greater exposure of tyrosine (Tyr) and tryptophan (Trp) residues compared to albumin and CPI. Circular dichroism (CD) data showed CPI presented more α-helix (14.4%) and less β-strand (30.7%) than albumin and glutelin. The atomic force microscope (AFM) profile and hydrodynamic diameter (D_h) determination showed the presence of low particle size in albumin fractions. Differences in the hydrophobicity (H_o) and the zeta-potential (ζ) of CPI, albumin, and glutelin were also observed due to their difference in structure and amino acid composition. Compared with CPI and glutelin, albumin exhibited the highest emulsifying activity (103.67 m²/g) and stability (42.84 min) and the smallest emulsion particle size (4.29 μm). The CPI, albumin and glutelin presented typical U-shaped protein solubility–pH curves, with the lowest solubility at pH 4.0. Rheological investigation demonstrated that CPIs were efficient in forming a gel at 80.6°C, whereas glutelin could form the hardest gel at 92.6°C. The overall results suggested that the cumin proteins can be a promising protein source for the food industry.     

Food protein functionality: A comprehensive approach

Food protein functionality has classically been viewed from the perspective of how single molecules or protein ingredients function in solutions and form simple colloidal structures. Based on this approach, tests on protein solutions are used to produce values for solubility, thermal stability, gelation, emulsifying, foaming, fat binding and water binding to name a few. While this approach is beneficial in understanding the properties of specific proteins and ingredients, it is somewhat restricted in predicting performance in real foods where the complexities of ingredients and processing operations have a significant affect on the colloidal structures and therefore overall properties of the final food product. In addition, focusing on proteins as just biopolymers used to create food structures ignores the biological functions of proteins in the diet. These can be beneficial, as in providing amino acids for protein synthesis or bioactive peptides, or these can be detrimental, as in causing a food allergic response. This review will focus on integrating the colloidal/polymer and biological aspects of protein functionality. This will be done using foams and gels to illustrate colloidal/polymer aspects and bioactive peptides and allergenicity to demonstrate biological function.     

绿豆分离蛋白功能特性研究

研究了绿豆分离蛋白的功能特性,探讨了pH值、温度、离子强度、蛋白质质量分数诸因素对绿豆分离蛋白溶解性、吸水性与吸油性、起泡性与起泡稳定性、乳化性与乳化稳定性、黏度的影响.结果表明,在pH=8的溶液中,绿豆分离蛋白的乳化性最好(45.2);在c(NaCl)=0.6 mol/L的溶液中,绿豆分离蛋白表现出较好的起泡性(160%);当w(绿豆分离蛋白)=9%时,起泡性和起泡稳定性最佳(分别为270%,77.8%～100%);当w(绿豆分离蛋白)=10%时,绿豆分离蛋白溶液的黏度可达7050 mPa·s.     

Biological quality and safety assessment of rice bran protein isolates

Three stabilisation techniques, microwave, dry heat and parboiling were applied to bran followed by enzymatic extraction, biological quality through growth and nitrogen balance study and safety assessment through 45 days feeding trial. Traits linked with protein bio‐evaluation were affected significantly by the test diets (P < 0.05), growth study parameters during the experimental remained as; PER from 1.97 to 2.18 with higher value for microwave stabilised protein isolates, net protein ratio of 4.43–5.14. Nitrogen balance study parameters too were better in microwave and dry heat stabilised protein isolates, while the lowest values were observed for parboiled protein isolates; true digestibility was within the range of 76.0–86.11% and biological value of extracted isolates was within the upper and lower limit of 78.57–88.23. No general ill effects were observed during the safety evaluation trial as the serum biochemical profile and organ to body weight ratio exhibited normal metabolic activity. Findings of current study are supportive for the suggestion that these extracted isolates can be safely used for variety of foods especially the designed formulations for protein deficient vulnerable groups especially from low socio‐economic countries.