Properties of acetylated potato protein preparations

The purpose of the present study was to determine the influence of protein isolation from potato juice and acetylation on the chemical composition and chosen functional properties of obtained preparations. Potato protein preparations used for the experiment were obtained by thermal coagulation and membrane technology. Preparations containing thermal coagulated (PPI) and native (PPC) protein, respectively, were subjected to the chemical modification by acetylation with the use of different doses of acetic anhydride. Changes in chemical composition (total and coagulable protein content, ash content and amino acid composition), functional properties (water holding capacity, oil holding capacity, protein solubility index, emulsification properties as well as foam capacity and stability) and extent of chemical modification were determined. The chemical composition and functional properties of obtained preparations were significantly different (p < 0.05).     

Functional properties of protein isolates,globulin and albumin extracted from Ginkgo biloba seeds

In this study, the functional properties of Ginkgo seed protein isolate (GPI), Ginkgo seed globulin protein (GGP) and Ginkgo seed albumin protein (GAP) extracted from Ginkgo biloba seeds were investigated. The protein contents of GPI, GGP and GAP were 91.0%, 93.4% and 87.8%, respectively in the samples in which the sugar, polyphenol and crude fibre were removed by the preparation procedure. For functional properties of Ginkgo seed proteins in the natural state, GAP showed the highest oil-absorption capacity (9.3 ml/g), foaming capacity (67.8%), emulsifying capacity (65.4%) and emulsion stability (90.6%); while GPI showed the highest water absorption capacity (1.93 ml/g), and GGP showed the highest foam stability (55.5%). The differences of the chemical components, surface hydrophobicity, disulphide bond (SS) and sulfhydryl group (SH) contents of GPI, GGP and GAP, which were correlated significantly with functional properties of Ginkgo seed proteins, were also investigated. The improved functional properties, such as water absorption capacity, solubility, foaming properties and emulsifying properties of Ginkgo seed proteins were observed in a pH range of 8.0–10.0 or sodium chloride concentration of 0.5–0.75 M.     

Composition and structure of carob (Ceratonia siliqua L.) germ proteins

This study was focused on the analysis of the chemical composition of defatted carob germ flour and the protein isolate. The amino acid composition and the nature of the subunits that compose carob germ proteins were also studied. Isolate was obtained by alkaline extraction followed by isoelectric precipitation of proteins. Results showed that an isolate of 96.5% of protein content was obtained. A high amount of amino acids like glutamic acid, aspartic acid and arginine was detected. Carob proteins were found to be composed by aggregates formed by a 131 and 70 kDa subunits linked by non-covalent bonds, and other peptides strongly bounded by disulfide interactions. Both, aggregates and subunits were formed mainly by 100 and 48 kDa monomers linked by disulfide bonds. A considerable content of high molecular mass peptides (HMWP) strongly bounded were also found. Proteins became partially denatured and thermally stabilized at acid pH (pH 2). These results could be useful in the study of different functional properties of carob germ proteins, and the application of these proteins as nutritional ingredients in formulated food.     

Characterization of protein isolates from different Indian chickpea (Cicer arietinum L.) cultivars

Protein isolates prepared by alkaline solubilization followed by isoelectric precipitation and freeze drying from desi (PBG-1, PDG-4, PDG-3, GL-769, and GPF-2) and kabuli (L-550) chickpea cultivars were evaluated for functional (water and oil absorption capacities, least gelation concentration, foaming capacity and stability) and thermal properties. Significant difference (P ? 0.05) in properties of kabuli and desi chickpea protein isolates was observed. Kabuli chickpea protein isolate showed significantly (P ? 0.05) higher ash (1.14%), protein (94.4%), L^∗, ΔE value, oil absorption capacity (OAC) and lower water absorption capacity (WAC) than their corresponding desi chickpea protein isolates. The solubility-pH profile of different protein isolates showed minimum solubility in the pH between 4.0 and 5.0 and two regions of maximum solubility at pH 2.5 and 7.0. Foaming capacity of all protein isolates increased with the increase in concentration. Kabuli chickpea protein isolate showed the highest foam stability (94.7%) after 120 min of storage. The thermal properties of protein isolates from different chickpea cultivars were studied by differential scanning calorimetry (DSC). Protein isolates from both the chickpea types differed significantly (P ? 0.05) in peak denaturation temperature (T_d) and heat of transition (ΔH). Kabuli type protein isolate exhibited lower T_d and ΔH value as compared to those from desi types. The interrelationships between characteristics of protein isolates showed a significant (P ? 0.05) negative correlation of T_d with protein content and OAC. It was also observed that cultivars with high fat content had high ΔH and lower WAC.     

Chemical composition and functional properties of raw and roasted Nigerian benniseed (Sesamum indicum) and bambara groundnut (Vigna subterranean)

Benniseed and bambara groundnut seeds were roasted at 80 and 120 °C for 10–60 min. For both flours, the effects of roasting temperature and time on selected functional properties and chemical composition were determined, as were the effects of pH on the emulsification capacity and nitrogen solubility. The chemical constituents of the raw flours were present at higher concentrations than those of the roasted flours except for fat and ash. Protein concentrates of both flours contained 80.5–81.5% crude protein as the major constituent. Nitrogen solubility was lowest at pH 4.0 for raw and roasted benniseed flour and pH 5.0 for raw and roasted bambara groundnut flour. Roasting generally lowered the nitrogen solubility and increased the water and oil absorption capacities while decreasing the foaming capacity and emulsification capacity of both flours.     

Improvement of functional properties of whey soy protein phosphorylated by dry-heating in the presence of pyrophosphate

The physicochemical and functional properties of a whey soyprotein (WSP), which was phosphorylated by dry heating, were investigated. The phosphorus content of WSP was 0.85 g/100 g by dry-heating at pH 4.0 for 5 days in the presence of pyrophosphate. ³¹P NMR spectral data suggested that the serine and sugar of WSP were phosphorylated. Although changes in the random coil structure of WSP measured by circular dichroism were mild, increased surface hydrophobicity and decreased tryptophan fluorescence intensity were observed following phosphorylation. Phosphorylation improved the stability against heat-induced insolubility, emulsifying properties, foaming properties, water absorption capacity, and oil absorption capacity of WSP. These results suggested that dry-heating phosphorylation is a useful method for improving the functional properties of WSP.     

Improvement of functional properties of chickpea proteins by hydrolysis with immobilised Alcalase

Limited chickpea protein hydrolysates ranging from 1% to 10% degree of hydrolysis were produced from chickpea protein isolate (CPI) using Alcalase immobilised on glyoxyl-agarose gels. Alcalase-glyoxyl derivative produced after 24 h of immobilisation at room temperature was 24 times more stable than soluble enzyme and presented approximately 51% of the activity of Alcalase. The chemical composition of chickpea hydrolysates were very close to that of CPI. Solubility, oil absorption, emulsifying activity and stability, and foaming capacity and stability were determined. All protein hydrolysates showed higher solubility than intact proteins, especially at pHs near isoelectric point of native chickpea proteins. Moreover, all hydrolysates had better functional properties, except emulsifying activity, than the original protein isolate.     

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.     

Isolation and study of the functional properties of pea proteins.

Proteins of pea seeds were isolated after defatting with hexane using alkaline (0.1 M sodium hydroxide) extraction and acid (HCl) precipitation. Concentrates were also prepared by hexane extraction and ethanolic extraction (pH = 5). Gross chemical composition amino acid content and functional properties (solubility profile, emulsifying--and foaming properties, water--and oil absorption) were studied. The results were compared with the same parameters of soy and lupin protein products. Although the majority of functional characteristics of isolates were lower in comparison to soy isolates, pea protein concentrate and isolate could be successfully used in bakery products for enrichment in protein and improvement of biological value. Their utilization as meat protein substitute in some Frankfurter type sausages is also possibly.     

Composition and functional properties of hemp seed protein isolates from various hemp cultivars

Hemp seed protein isolates (HPI) were extracted from seven commercial hemp cultivars, a Cornell breeding line, and a commercial hemp heart product, and their composition and functional properties were investigated. HPI contained different ratios of edestin, vicilin, and albumin proteins, which affected protein solubility and functionality. Higher protein solubility was associated with cultivars that contained more vicilin and albumin, which influenced the subsequent functional properties of HPI. Significant differences in water holding capacity (0.83–1.05 g water/g protein isolate), oil holding capacity (1.28–1.81 g oil/g protein isolate), foam capacity (52.9%–84.9%), and foam stability (68.1%–89.4%) were observed across HPI. The Cornell hemp breeding line exhibited the highest protein solubility at pH 7.0 and was uniquely capable of forming an emulsion. The relationship identified between hemp seed protein composition and functionality, in conjunction with the demonstration of an on-going hemp breeding line, suggest that continued, targeted development of hemp cultivars can improve its seed protein functional properties for ingredient utilization in plant-based foods.     

Isolation and study of the functional properties of pea proteins

Proteins of pea seeds were isolated after defatting with hexane using alkaline (0.1 M sodium hydroxide) extraction and acid (HCl) precipitation. Concentrates were also prepared by hexane extraction and ethanolic extraction (pH = 5). Gross chemical composition amino acid content and functional properties (solubility profile, emulsifying – and foaming properties, water – and oil absorption) were studied. The results were compared with the same parameters of soy and lupin protein products. Although the majority of functional characteristics of isolates were lower in comparison to soy isolates, pea protein concentrate and isolate could be successfully used in bakery products for enrichment in protein and improvement of biological value. Their utilization as meat protein substitute in some Frankfurter type sausages is also possibly.     

Effects of barley flour and barley protein isolate on chemical, functional, nutritional and biological properties of Pita bread

This study was carried out to investigate the effects of fortification of wheat flour with barley flour (BF) and barley protein isolate (BPI) at three levels; 5, 10 and 15% levels on the chemical composition, nutritional evaluation and biological properties of pita bread. Proteins fractions such as globulin, prolamin, glutelin-1 and glutelin-2 as well as protein isolates were extracted from barley flour and evaluated for protein yield, chemical composition and nutritional quality. Highest yield and essential amino acids contents were obtained in barley protein isolate. SDS-PAGE gels electrophoresis indicated that fortified wheat flour with BPI and BF consists of proteins coming from wheat flour and barley proteins. The contents of essential limiting amino acids in bread were increased from 1.38 to 3.10 g/100 g for lysine and from 0.86 to 1.73 g/100 g for methionine as the ratio of fortification with BF and BPI increased from 0 to 15%. The highest content of total phenolics, antioxidant activity, and inhibitory activity for both angiotensin converting enzyme (ACE) and α-amylase were found in fortified bread with BPI at 15%. Results indicated that bread made from fortification of wheat flour with BF and BPI at 15% showed superior chemical, physico-chemical, nutritional and biological properties.     

碱性蛋白酶限制性水解对高温菜籽粕蛋白功能性质的影响

为改善高温菜籽粕蛋白质的功能性质,用碱性蛋白酶对其进行限制性水解,并研究不同水解度(DH)高温菜籽粕蛋白功能性质及相对分子质量分布。结果表明：碱性蛋白酶限制性水解高温菜籽粕蛋白的溶解度、乳化性和吸油性均有所改善,其中溶解度随水解度增加而增加,pH7.0 时DH为10% 的高温菜籽粕蛋白的溶解度达63.82%,是原蛋白溶解度的2.1 倍;DH 为2.0% 的水解蛋白乳化性最好,pH6.0 和pH8.0 时乳化指数分别为0.43 和0.49,比原蛋白乳化指数分别高0.13 和0.11;DH 为8% 的水解蛋白吸油性最好,为4.39g/g。水解后高温菜籽粕蛋白的某些功能性质与其相对分子质量分布有一定的关系,需控制高温菜籽粕蛋白水解度以获得某种良好的功能性质。     

Effect of extraction and isolation on physicochemical and functional properties of an underutilized seed protein: Gingerbread plum (Neocarya macrophylla)

The effect of extraction and isolation on the physicochemical and functional properties of gingerbread plum seed protein isolate was studied. Gingerbread plum seed protein isolate was extracted from defatted gingerbread plum seed flour (DGPSF) by alkali solution along with isoelectric precipitation. The protein isolate was subjected to freeze or vacuum drying process. Freeze dried gingerbread plum seed protein isolate (FGPSPI) and vacuum dried gingerbread plum seed protein isolate (VGPSPI) were evaluated for their physicochemical and functional properties (protein solubility, water/oil binding capacity, emulsifying capacity, foaming capacity). Among physicochemical parameters, the proximate composition, amino acid composition, minerals, differential scanning calorimetry (DSC), SDS-PAGE and color attributes were studied. Both FGPSPI and VGPSPI contained over 90% protein versus DGPSF (56.72%) used as raw material. The method of drying had significant effect (p < 0.05) on the physicochemical characteristics of FGPSPI and VGPSPI except for amino acids composition. The functional properties were variable among samples. DGPSF had higher emulsifying, water holding and oil binding capacities compared with FGPSPI and VGPSPI. FGPSPI exhibited better emulsifying capacity and water holding capacity than VGPSPI. FGPSPI also showed comparable oil binding capacity and bulk density to commercial soy protein isolate (SPI). The results indicated that FGPSPI and VGPSPI could be a good source of protein fortification for a variety of food products for protein deficient consumers as well as a potential food ingredient.     

大豆分离蛋白的磷酸化改性研究

采用三聚磷酸钠 (STMP)对大豆分离蛋白 (SPI)进行磷酸化改性。研究了不同改性程度下SPI功能特性的变化。结果表明 :磷酸化SPI等电点由 pH 4 4 1移至pH 3 86,溶解性、乳化能力和持水性也有明显提高     

Structural and Functional Properties of Hemp Seed Protein Products

The effects of pH and protein concentration on some structural and functional properties of hemp seed protein isolate (HPI, 84.15% protein content) and defatted hemp seed protein meal (HPM, 44.32% protein content) were determined. The HPI had minimum protein solubility (PS) at pH 4.0, which increased as pH was decreased or increased. In contrast, the HPM had minimum PS at pH 3.0, which increased at higher pH values. Gel electrophoresis showed that some of the high molecular weight proteins (>45 kDa) present in HPM were not well extracted by the alkali and were absent or present in low ratio in the HPI polypeptide profile. The amino acid composition showed that the isolation process increased the Arg/Lys ratio of HPI (5.52%) when compared to HPM (3.35%). Intrinsic fluorescence and circular dichroism data indicate that the HPI proteins had a well‐defined structure at pH 3.0, which was lost as pH value increased. The differences in structural conformation of HPI at different pH values were reflected as better foaming capacity at pH 3.0 when compared to pH 5.0, 7.0, and 9.0. At 10 and 25 mg/mL protein concentrations, emulsions formed by the HPM had smaller oil droplet sizes (higher quality), when compared to the HPI‐formed emulsions. In contrast at 50 mg/mL protein concentration, the HPI‐formed emulsions had smaller oil droplet sizes (except at pH 3.0). We conclude that the functional properties of hemp seed protein products are dependent on structural conformations as well as protein concentration and pH.     

Physicochemical and Functional Properties of Winged Bean Flour and Isolate Compared with Soy Isolate

The proximate composition, amino acid profile and functional properties of isolated winged bean proteins were determined and compared with soy protein isolate. Winged bean protein extracted at pH 10 and pH 12 had protein contents of about 90% and 80%, respectively. Alkali extraction of winged bean proteins at pH 10 and pH 12 did not affect the amino acid distribution of the isolated proteins. Oil and water absorption, emulsion, and foaming properties of winged bean isolated compared favorably with soy isolate. Least gelation concentration for winged bean isolate was 18% compared to 14% for soy isolate. Thus, winged bean protein isolate with its high protein content, high lysine and other essential amino acid content and good functionality has a good potential as an ingredient in food products.     

Nutritional and functional properties of Vicia faba protein isolates and related fractions

The goal of this research was the characterisation of Vicia faba (broadbean) protein isolates and related fractions in order to determine whether this grain legume could be used for production of high quality protein products and other fractions rich in functional components. Alkaline extraction of the defatted seed flour, followed by precipitation at the isoelectric pH, yielded a 92% protein isolate with a high oil absorption capacity. The contents of the favism-inducing glycosides, vicine and convicine, in the isolate were reduced by more than 99% as compared to the original flour, although the amino acid composition was similar to that of the flour. Some of the by-products of protein isolate production may also be of interest from a nutritional and functional point of view. Thus, the oil resulting from hexane extraction of the flour is rich in unsaturated fatty acids, and polyphenols (resulting from extraction of the defatted flour with acetone) showed a high ABTS radical-scavenging activity. In addition, the solid residue (resulting from protein solubilisation) was high in fibre and showed good water absorption. These results show good nutritional and functional properties in V. faba protein isolates and related fractions, which may favour the revalorisation of this traditional bean crop.     

Amino acid composition and functional properties of collagen polypeptide from Yak (Bos grunniens) bone

Collagen polypeptide was prepared from Yak bone by applying papain as a catalyst. Its relative molecular weight distribution and amino acid composition were determined. Moreover, its main functional properties including water and oil absorption, water-holding capacity, emulsifying ability and stability, foaming ability and foam stability were investigated. The polypeptide had a molecular weight distribution of 11.7-43 kDa, in which most distributed at 11.7-25.3 kDa. It was high in glycine, alanine, proline, hydroxyproline and glutamic acid but low in methionine, tyrosine and histidine, the total amino acid amount being 88.06 g/100 g. The polypeptide showed good water adsorption, water-holding capacity, oil absorption, emulsifying and foaming properties. It is hoped to be applied in food and cosmetic.     

Physico-chemical, amino acid composition, functional and antioxidant properties of roe protein concentrates obtained from Channa striatus and Lates calcarifer

Roe protein concentrates prepared from Channa striatus (CRPC) and Lates calcarifer (LRPC) were investigated for physico-chemical characteristics, amino acid composition, functional properties and antioxidant activity. Channa and Lates roes yielded 20.7% and 22.5% of protein concentrates possessing 90.2% and 82.5% protein, respectively. Major differences were not observed in each of the amino acids except leucine in CRPC and LRPC. The solubility of protein was 3.93-54.6% and 1.6-55.5% over a pH range of 2-12 in CRPC and LRPC, respectively. Water absorption, oil absorption, foam capacity, stability and emulsifying capacity were found to be higher in CRPC than in LRPC. Antioxidant activity determined by the radical scavenging activity and ferric reducing power was higher in CRPC. SDS-PAGE of both roe protein concentrates showed protein bands of 170, 95 and 55 kDa. Moisture sorption isotherms of protein concentrates indicated their hygroscopic nature.