Lupinus angustifolius protein isolates: chemical composition,functional properties and protein characterization

Two types of protein isolates were prepared from Lupinus angustifolius defatted flour by alkaline extraction, with (Isolate B) and without (Isolate A) sodium sulphite, and acid precipitation of proteins at the isoelectric point (IEP 4.3). Chemical composition, main functional properties and protein composition of L. angustifolius defatted flour and protein isolates were determined. Isolate A and B have 93.9 and 84.6% protein content, respectively, and had a balanced composition of essential amino acids, with respect to the FAO pattern except for lysine. The in vitro protein digestibility ranged between 86.3 and 93.9% for isolate A and B, respectively.     

Peanut protein concentrate: Production and functional properties as affected by processing

Peanut protein concentrate (PPC) was isolated from fermented and unfermented defatted peanut flour by isoelectric precipitation and physical separation procedures. PPC was dried by spray or vacuum drying. PPC powders from each drying technique were evaluated for proximate composition and functional properties (protein solubility, water/oil binding capacity, emulsifying capacity, foaming capacity and viscosity) along with defatted peanut flour and soy protein isolate as references. PPC contained over 85% protein versus 50% protein in the defatted peanut flour used as raw material for PPC production. PPC had a solubility profile similar to that of peanut flour, with minimum solubility observed at pH 3.5–4.5 and maximum solubility at pH 10 and higher. Roasting of peanut reduced all functional properties of defatted peanut flour while fermentation had the reverse effect. The type of drying significantly affected the functional properties of PPC. Spray dried PPCs exhibited better functional properties, particularly emulsifying capacity and foaming capacity, than vacuum oven dried PPC. Spray dried PPCs also showed comparable oil binding and foaming capacity to commercially available soy protein isolate (SPC). At equivalent concentrations and room temperature, PPC suspension exhibited lower viscosity than soy protein isolate (SPI) suspensions. However, upon heating to 90 °C for 30 min, the viscosity of PPC suspension increased sharply. Results obtained from this study suggest that the PPC could be used in food formulations requiring high emulsifying capacity, but would not be suitable for applications requiring high water retention and foaming capacity. PPC could be a good source of protein fortification for a variety of food products for protein deficient consumers in developing countries as well as a functional ingredient for the peanut industry. The production of PPC could also add value to defatted peanut flour, a low value by-product of peanut oil production.     

Effect of lipoxygenase activity in defatted soybean flour on the gelling properties of soybean protein isolate

Soybean lipoxygenase was inactivated to different degrees by dry heating of defatted soybean flour for 0, 5, 10, 15, 20 and 25 min and soy protein isolates were prepared thereof by isoelectric precipitation of the water extract of the defatted soybean flour. The fluorescence emission intensity at 420 nm of the chloroform–methanol extract of soy protein isolates, which was indicator of the existence of peroxidized lipid, varied in parallel with the lipoxygenase residual activity in defatted soybean flours. The dispersion of soy protein isolate showed an increasing turbidity with the increase of lipoxygenase residual activity in the starting defatted soybean flour, suggesting an elevated tendency to form insoluble aggregates during the preparation of soy protein isolate. Small deformation rheological test revealed that the gelling times were shorter for those soy protein isolates derived from low lipoxygenase activity defatted soybean flours than that of high lipoxygenase activity. Frequency sweep showed that G′ of soy protein isolate derived from low lipoxygenase defatted soybean flour was independent of oscillation frequency in contrast to that of derived from non dry-heated defatted soybean flour, the latter showed a marked frequency dependence. Large deformation test revealed that the gel hardness increased about 10 times after dry heating of defatted soybean flour for 20 min. As the increase of the lipoxygenase residual activity, the gel permeability increased markedly, suggesting that soy protein isolate from high lipoxygenase defatted soybean flour produced coarser textured gel, which corresponded well with the results of scanning electron microscopy.     

Functionality of Flours, Protein Fractions and Isolates from Field Peas and Faba Bean

Field pca and faba bean proteins are rich sources of lysine, and air classification of the pin milled flours essentially doubled the protein contents in the protein fractions. The proteins in these flours and protein fractions were highly soluble at acid pH and exhibited only a narrow range of insolubility at pH 4–5. Water holding and oil absorption capacities increased in proportion to protein contents of the flour, protein fraction, and isolate of each legume, including soybean flour and isolate, but oil emulsification properties were uniformly high among all products. The protein fractions exhibited excellent whipp-ability and foam stability compared to soybean controls, and their promising functional properties suggested potential applications in meat emulsions, beverages and bakery products.     

Nitrogen extractability and functional properties of defatted Erythrina variegata flour

Defatted Erythrina variegata flour was prepared from dehusked seed meal by hexane extraction of residual oil. The resulting flour had 403 g kg⁻¹ of protein as compared to 282 g kg⁻¹ in the whole seed-defatted meal. Nitrogen extractability of the defatted flour in water was not much influenced by the length of extraction period above 40 min, but an increased extraction was observed at a higher liquid to solid ratio up to a studied limit of 1:60; the optimal ratio was found to be 1:30. The minimum of 26.9% nitrogen was extracted in the pH range 3.0–4.0 and maximum of 94.8% at pH 12. Addition of sodium chloride (0.1 or 0.5 M) broadened the pH range of minimum nitrogen extractability and shifted it toward a lower pH region. At both concentrations of sodium chloride, a marked increase in nitrogen extractability, in the pH range 3.0–7.0, was observed. Precipitation of protein from an extract of pH 10.0 was maximum (85.3%) at pH 4.75. A higher buffer capacity of the flour was observed in the acidic medium (0.195 mmol HCl g⁻¹ flour) than in alkaline medium (0.093 mmol NaOH g⁻¹). Water absorption and oil absorption values for the whole E. variegata seed flour and the dehusked, defatted flour were 1.81, 1.43 and 1.02, 1.52 kg kg⁻¹, respectively.     

大麻蛋白的营养评价

本文以脱脂大麻籽粉为原料,采用碱溶酸沉法提取大麻分离蛋白(HPI)及其11S组分(HPI-11S)、7S组分(HPI-7S),对其进行氨基酸组成分析,并应用胃蛋白酶-胰蛋白酶体外消化模拟实验评价大麻蛋白的营养价值,结果表明:与大豆分离蛋白相比,大麻蛋白富含人体所需的必需氨基酸,消化性能更优,属优质蛋白质.     

Functional properties and chemical composition of fractionated brown and yellow linseed meal (Linum usitatissimum L.)

Considering its high content of protein and dietary fiber, linseed meal is a remarkable source for food ingredient and food additive production. In this study, brown and yellow linseed meal (Linum usitatissimum L.) were fractionated via pH control, to obtain five linseed meal fractions rich in protein and fiber. The fractions were characterized by measuring functional properties, proximate and carbohydrate composition, and lignan contents. Acid soluble protein fractions were characterized by lower emulsification capacities and foaming activities in comparison to a commercial soy protein isolate. Alkaline soluble protein fractions showed emulsification activities comparable to whole egg and relatively high contents of secoisolariciresinol diglucoside (SDG) of 110 mg/g DM and 56.2 mg/g DM, respectively. The good emulsification and foaming activities, as well as the enriched concentration of SDG and therefore high nutritional value, make especially the alkaline soluble protein fraction highly interesting for food ingredient production.     

Characteristics of Isolation and Functionality of Protein from Tomato Pomace Produced with Different Industrial Processing Methods

The seeds separated from tomato pomace may contain valuable protein with unique functional properties. The objectives of this research were to study the impact of industrial hot and cold break tomato processes on protein isolation from defatted tomato seed meal and determine the protein-related functional properties of defatted and non-defatted seed meals. The results showed that the high temperature of hot break process denatured the protein, resulting in the lower protein extraction yield from 9.07 % to 26.29 % for defatted hot break tomato seed (DHTS) compared to from 25.60 % to 32.56 % for defatted cold break tomato seed (DCTS) under various extraction conditions. Hot break process also significantly influenced protein-related functional properties of seed meals. Compared to DCTS, DHTS had higher water absorption capacity (WAC) and oil absorption capacity (OAC) based on the protein weight in the seed meal, but lower emulsifying ability (EA), emulsifying stability (ES), foaming capacity (FC), and foaming stability (FS) based on the whole seed sample weight. When compared to commercial soybean protein isolate (SP), the meals of hot break tomato seed (HTS), DHTS, and DCTS showed higher bulk density and WAC values. The FC and FS of tomato meals were inferior while the ES was superior to SP. High alkaline pH was beneficial to the protein extraction and achieved better EA, ES, FC and FS of all the samples. The results indicated that tomato seed meals have a great potential to be used as functional food ingredients.     

Macadamia oil extraction methods and uses for the defatted meal byproduct

BackgroundThe trend towards the consumption of functional foods that aid in the maintenance of human health has increased in recent decades. In this way, macadamia nut contains bioactive compounds and high levels of monounsaturated fatty acids that are beneficial to health and can be minimally processed or industrialized for the production of oil and defatted flour.Scope and approachThe extraction of macadamia oil is commonly performed by cold pressing; however, the process presents low extraction yields, generating partially defatted meal as a byproduct, which can be subjected to further processing to increase the yield of oil extraction. Thus, studies about different methods of extraction and evaluation of the defatted material properties, such as color, water and oil holding capacity and solubility of the protein fraction were considered in this work.Key findings and conclusionsIt was found that the fatty acid composition of macadamia oil allows for its diverse use in many industries, i.e. cosmetics and pharmaceutical, while evaluation of the functional properties of the protein fraction of the defatted meal have shown that this byproduct can be used in food industry. Subsequent studies of the macadamia oil extraction process should enable the preservation of oil quality, in terms of fatty acid composition and bioactive compounds, and the functional properties of the defatted meal.     

Antioxidant and chelating activity of Jatropha curcas L. protein hydrolysates

BACKGROUND: Antioxidant and chelating activities were determined in protein hydrolysates that were produced by treating a protein isolate of a non‐toxic genotype of Jatropha curcas with the protease preparation alcalase. RESULTS: 50 min protein hydrolysate with a degree of hydrolysis of 31.7% showed highest antioxidant and chelating activity. These activities were also determined in six peptidic fractions that were separated by gel filtration chromatography of the 50 min hydrolysate. The lower‐molecular‐weight peptidic fractions had the highest antioxidant and chelating activities, which correlated with a higher content in antioxidant and chelating amino acids such as tyrosine and histidine. CONCLUSION: Results show that J. curcas represents a good source of bioactive peptides. This may be important for the revalorization of defatted J. curcas flour, a by‐product resulting form oil extraction for biodiesel production. This is especially important in Third World and developing countries such as Mexico. Copyright © 2011 Society of Chemical Industry     

Effects of Acylation of Defatted Cottonseed Flour with Various Acid Anhydrides on Protein Extractability and Functional Properties of Resulting Protein Isolates

Maleylation, succinylation, dimethylglutarylation, and sodium sulfite treatment of cottonseed flour increased protein extraction from the flour in suspension, and precipitated more protein in the extract at pH 4.0, compared to unmodified flour processed through conventional methods. However, acetylation decreased protein extraction and precipitation at this pH. Protein isolates from succinylated, maleylated and dimethylglutarylated flours were highly water-soluble, and did not coagulate by heating. Acetylation decreased heat coagulability of the resulting protein isolate, but did not affect water solubility of the isolate. Treatment of the flour with sodium sulfite markedly increased heat coagulability of the isolate, and decreased its solubility. Oil absorption capacity of the isolate was increased slightly by dimethylglutarylation, but other treatments did not affect the capacity significantly. Sensitivity of proteins in isolates to calcium ions was not affected by acylation or sodium sulfite treatment of the flour.     

Factors affecting production of melon seed kernel protein: Yield,composition and protein isolates quality

Extraction and precipitation were investigated to determine the opti-mal conditions for preparation of protein concentrates from defatted melon seed kernels flour. Protein concentrates were prepared by extraction with distilled water, salt or alkaline solution. Alkaline so-lution led to the highest extraction yield of 84.5%. The protein concen- trate has a good digestibility of 90.8% as determined by in vitro enzy-matic method. The protein is rich in lysine 6.35% but poor in sulphur-containing amino acids such as methionine 0.27%, and cystine 0.33%. The protein isolate showed good whipping and emulsifying character-istics as well as water and oil absorptions.     

Chickpea protein isolates obtained by wet extraction as emulsifying agents

BACKGROUND: Wet extraction of protein from defatted chickpea (variety Thiva (T), Greece) flour, at alkaline or slightly acidic pH, followed by isoelectric precipitation (pI) or ultrafiltration (UF) to recover the protein, was employed to obtain a number of chickpea protein isolates, enriched either in protein constituents belonging to the globulin (TpI, TUF, TUFG) or to the albumin fraction (TUFA). RESULTS: The interfacial activity and film‐forming ability of the isolate protein constituents as well as their emulsifying properties were evaluated. The method applied for chickpea protein isolate preparation influenced to an appreciable extent their composition, adsorption behaviour to oil–water interfaces and emulsion formation and stabilization characteristics, especially with respect to oil droplet flocculation and coalescence. The isolates also differed in their ability to stabilize emulsions subjected to thermal processing or following storage under freezing conditions. The results are discussed in terms of compositional and, possibly, structural differences existing between the protein constituents of the chickpea isolates that may influence their functional behaviour in emulsion systems. CONCLUSION: The method applied for isolate preparation influenced to an appreciable extent the ability of proteins to adsorb to the oil–water interface and stabilize emulsions during long‐time ageing or following heat treatment or freezing. Copyright © 2009 Society of Chemical Industry     

Physicochemical and functional properties of flour and protein isolates extracted from seinat (Cucumis melo var. tibish) seeds

The physicochemical and functional properties of seinat seed flour (SSF), defatted seinat flour (DSSF), and protein isolates were studied. Protein was extracted from DSSF using an alkali solution with isoelectric precipitation and freeze drying. Freeze dried seinat seed protein isolates (FSSPI), SSF, and DSSF were evaluated for their physicochemical and functional properties. SSF contained high levels of crude fat and fiber (31.13% and 24.75%, respectively). FSSPI contained 91.83% protein versus 28.58% for SSF. The amounts of potassium, the mineral with the highest content, were 9,548.33, 6,439.03, and 1,029 mg/100 g in SSF, DSSF, and FSSPI, respectively. The functional properties were variable among samples. The protein solubility of FSSPI was significantly higher (p<0.05) than for DSSF and SSF. FSSPI has a significantly better (p<0.05) foaming capacity, water/fat absorption capacity, and bulk density than SSF and DSSF. FSSPI also showed an emulsifying capacity comparable to commercial soy protein isolates.     

Extraction of nitrogenous material from winged bean [Psophocarpus tetragonolobus (L.) DC] flour and the preparation and properties of protein isolates

The extractability of nitrogenous material from the seeds of 12 winged bean accessions has been investigated. Little variation in nitrogen content and extractability in water or salt solution was obtained, although decortication considerably reduced the levels of extraction. The effect of three oil extraction procedures on the extractability of nitrogenous material at different pH values is reported. Protein isolates were prepared and simple laboratory tests were used to evaluate their functional properties. The prepared winged bean isolates possessed very low bulk densities and high fat absorption values and the relationship between these factors was investigated further. Winged bean isolates showed high (100%) nitrogen dispersibilities and were able to form heat-stable emulsions. They did not form gels under the conditions used except in the presence of CaCl₂. Isolates prepared from unheated winged bean flour formed stiff but unstable foams. The relationship between the oil extraction procedure and isolate yield, purity and functional properties is discussed.     

The Effects of Protein‐Rich Fraction and Defatting on Pasting Behavior of Chickpea Starch

Starch and protein‐rich fractions were isolated from both defatted and undefatted chickpea flour. Starch with a high purity was obtained by the isolation method used. Each of the protein‐rich fractions was added to the respective starch fraction at different levels to obtain mixtures with a range of protein contents. The viscosities of these mixtures were analyzed using the Rapid Visco Analyser (RVA). Increased protein content of the starch and protein‐rich fraction mixtures, obtained from defatted chickpea flour, resulted in distinctive resistance to shear thinning. The same behavior was not observed in case of starch and protein‐rich fraction mixtures obtained from undefatted chickpea flour. Undefatted samples exhibited a sharp pasting peak in RVA curves as generally expected from starch‐based systems, but unexpectedly, a sharp peak was not observed in defatted samples having protein content up to 4.8%. Peak, breakdown and cold‐stage viscosity values of the mixtures obtained from undefatted chickpea flour were higher than those of defatted ones at the corresponding protein levels. The results implied that the lipids and their interaction with starch played an effective role in the gelatinization, pasting and cooling stage viscosity values of the RVA curves.     

Effects of protein solubilisation and precipitation pH values on the functional properties of defatted wheat germ protein isolates

Wheat germ protein isolates were prepared from defatted wheat germ flour using alkaline solubilisation and acid precipitation. A central composite design with two independent variables (solubilisation pH and precipitation pH) and bivariate correlations was selected for the correlation analysis of the protein separation conditions and the functional properties. The results showed that the protein yield (Y) and functional properties of isolates, such as water absorption (WA) and fat absorption (FA), were sensitive to both solubilisation pH and precipitation pH, whereas the emulsification was sensitive to only solubilisation pH. Emulsifying activity (EA) and FA of isolates showed a high positive correlation with yield. Gel electrophoresis analysis of protein fractions gave evidence to the compositional changes between proteins isolated under different conditions, highly alkaline conditions result in the degradation of protein chains and formation of toxic compounds. Surface hydrophobicity suggested that proteins tend to be more denatured when solubilised at highly alkaline conditions. These conformational and compositional changes due to different protein separation conditions have contributed to the changes in functional properties of protein isolates.     

Factors affecting production of a near-white protein isolate from grapeseed

Extraction and precipitation conditions were investigated to determine the optimum conditions for preparation of a near-white protein isolate from grapeseed flour, treated with ammonium hydroxide and defatted. Extraction and precipitation of protein was studied under the following conditions: Particle size (<20 to >80 mesh). flour to solvent ratio (1:5–1:40), pH (1–12), NaCl medium (1–10%), extraction time (15–60 min) and precipitation pH (3–5). Protein solubility was less than 65% above pH 10. Using 60–80 mesh flour and extracting at pH 11 for 30 min with a flour to solvent ratio of 1:15, a protein isolate was obtained by acidification to pH 4.5 containing 84.7% protein and representing 48.2% of the crude protein in the grapeseed. The isolate was relatively low in sulphur-containing amino acids and lysine but rich in other essential and non-essential amino acids and had a digestibility of 91.3%. The isolate showed reasonably good whipping and emulsifying characteristics as well as water and oil absorptions.     

Effect of denaturation during extraction on the conformational and functional properties of peanut protein isolate

Peanut protein isolate (PPI) was extracted by alkali dissolution and acid precipitation from defatted peanut flour. The effects of extraction conditions on the denaturation and functional properties of PPI were investigated. In comparison with native peanut protein (NPP) which was extracted by ammonium sulfate, the PPI extracted by alkali dissolution and acid precipitation had a higher extent of denaturation. Arachin was affected more easily by the extraction process than conarachin and led to a noticeable decrease of thermal stability of PPI. PPI contained much lower sulfhydryl and disulfide bond contents than NPP. The analyses of intrinsic fluorescence spectra indicated a more compacted tertiary conformation of NPP than PPI. Extraction process influenced the functional properties of PPI, such as protein solubility, emulsifying activity index and foaming capacity. The relatively poor functional properties of PPI might be associated with protein denaturation/unfolding and subsequent protein aggregation.

Industrial relevance

Peanut is an important oilseed crop and a well-accepted food. After oil production through thermal treatment, the defatted peanut flour is the main byproduct, which possesses a large amount of proteins. However, due to the low extraction yield and poor functional properties of these proteins, they are not well utilised in industry till now. In this work, peanut proteins were extracted by two techniques. The results indicated that extraction technique could significantly modify the functional properties of peanut proteins. Therefore, this work is helpful for industrial utilisation of peanut proteins.     

Production of guava seed protein isolates: Yield,composition and protein quality

The optimum conditions were determined for the preparation of protein isolates from ground, defatted guava seed flour. The isolates were obtained by micellisation and isoelectric precipitation techniques. The isoelectric point of guava seed protein was found to be pH 4.5 with a protein solubility of more than 85% above pH 9. Using 40–80 mesh particle size and extracting at pH 10 for 30 min, an isoelectric isolate was obtained by acidification to pH 4.5 which was 85.4% of the starting protein compared to 18.3% for micellisation protein obtained by twofold dilution with cold distilled water of 5% NaCl protein extract. The isolates were easily digested by the pepsin-pancreatin enzyme system and were comparable to casein. The amino acid composition showed that guava seed flour and isolates were deficient in sulphur-containing amino acids and in lysine, but contained the other essential amino acids in adequate levels. The micellisation isolate had higher fat absorption and emulsion stability than the isoelectric isolate, while other functional properties were almost similar.