Preparation Of Protein Isolate Research Articles

Modification of the physicochemical, functional, biochemical and structural properties of a soursop seed (Annona muricata L.) protein isolate treated with high-intensity ultrasound

The obtained seeds from fruit processing are considered by-products containing proteins that could be utilized as ingredients in food manufacturing. However, in the specific case of soursop seeds, their usage for the preparation of protein isolates is limited. In this investigation a protein isolate from soursop seeds (SSPI) was obtained by alkaline extraction and isoelectric precipitation methods. The SSPI was sonicated at 200, 400 and 600 W during 15 and 30 min and its effect on the physicochemical, functional, biochemical, and structural properties was evaluated. Ultrasound increased (p < 0.05) up to 5 % protein content, 261 % protein solubility, 60.7 % foaming capacity, 30.2 % foaming stability, 86 % emulsifying activity index, 4.1 % emulsifying stability index, 85.4 % in vitro protein digestibility, 423.4 % albumin content, 83 % total sulfhydryl content, 316 % free sulfhydryl content, 236 % α-helix, 46 % β-sheet, and 43 % β-turn of SSPI, in comparison with the control treatment without ultrasound. Furthermore, ultrasound decreased (p < 0.05) up to 50 % particle size, 37 % molecular flexibility, 68 % surface hydrophobicity, 41 % intrinsic florescence spectrum, and 60 % random coil content. Scanning electron microscopy analysis revealed smooth structures of the SSPI with molecular weights ranging from 12 kDa to 65 kDa. The increase of albumins content in the SSPI by ultrasound was highly correlated (r = 0.962; p < 0.01) with the protein solubility. Improving the physicochemical, functional, biochemical and structural properties of SSPI by ultrasound could contribute to its utilization as ingredient in food industry.

Persian everlasting pea (Lathyrus rotundifolius L.) protein isolate as a potential protein source for food application: Effect of ultrasound‐assisted extraction method on the properties of the protein isolates

AbstractFinding new protein sources and processes comprising targeted functional properties is crucial for the increasing global food demand. In the current paper, a new protein isolate is introduced with potential benefits based on the seeds of Persian everlasting pea (Lathyrus rotundifolius L.). Conventional aqueous extraction for the preparation of protein isolates (CPEP) was compared with pre‐ultrasonic (PUPEP) and ultrasound‐assisted (UAPEP) extractions, and the physicochemical and functional properties of the proteins were investigated. By the implication of ultrasound trials, protein recovery was increased from 49.88% for CPEP to 55.02% and 56.11%, for PUPEP and UAPEP, respectively. According to gel electrophoresis, no major distinction in molecular weight between protein fractions of different samples was perceived and sonication practice did not convert the primary structures of proteins. FTIR results uncovered changes in different extraction modes, implying that ultrasound could transform the secondary structures of the protein. Thermal properties and surface tension were decreased during sonication due to the conformational changes. The results of this study indicated that Persian everlasting pea protein isolate could be considered as a novel source of valuable protein and functional ingredient in the food industry.Practical applicationsThe utilization of plant‐based protein products as sustainable alternatives to animal proteins has been increasing recently. However, compared with animal proteins, plant‐based proteins reveal relatively weak functional properties such as water‐holding capacity and gelation. Therefore, they need to be modified before being incorporated into food products. Ultrasonic treatment is an emerging technology that has many applications in food science and technology, such as increasing the extraction efficiency and improving the physicochemical and functional properties of food ingredients. Lathyrus rotundifolius seeds contain high amounts of protein and can be used as a source of plant‐based protein. The effect of ultrasonic treatment in the study was investigated and confirmed to improve the extraction efficiency and functional properties of Persian everlasting pea protein, which can be used in the food industry.

Effective valorization of agro‐waste of castor oil extraction industry as feedstock for sustainable fish production

AbstractCastor protein isolate (CPI) was prepared by aqueous solubilization of defatted castor kernel meal under alkaline conditions (pH 12.0), with precipitation at the isoelectric point (pH 5.0) followed by heat treatment. Five experimental diets were prepared by substituting soybean protein isolate (SPI) at 0%, 25%, 50%, 75%, and 100% with CPI based on protein equivalent basis. The diets were assigned as control, PI25, PI50, PI75, and PI100, respectively. A 60‐day feeding trial was conducted following a completely randomized design. Results revealed significant improvement in growth rates, feed conversion, and protein retention in Labeo rohita fingerlings (P &lt; 0.05) at 124.50 g CPI kg−1 diet (PI75). However, these were similar between control and PI100 (P &gt; 0.05). Dietary CPI did not alter the hepatosomatic index, viscerosomatic index, survival, carcass composition (except crude protein), and digestive enzymes (P &gt; 0.05). The metabolic enzymatic profile of rohu fingerlings was significantly affected due to dietary treatments (P &lt; 0.05) but oxidative stress enzymes were not affected by feeding of CPI. The activity of the aminotransferases, lactate dehydrogenase, and malate dehydrogenase did not differ (P &gt; 0.05) between control and PI100. The preparation of protein isolate is therefore a way forward for the effective valorization of toxic castor meal and could be used at 164.0 g kg−1 inclusion (complete substitution of soybean protein isolate) in the diet of L. rohita. © 2021 Society of Industrial Chemistry and John Wiley &amp; Sons Ltd.

Phytochemical Profile and Bioactivity of Industrial Rapeseed Meal Ethanol-Wash Solutes

Rapeseed meal is a by-product of oil producing industry which contains a high amount of protein (37–42%). To prepare protein isolates, suitable for human nutrition, the industrial rapeseed meal is often subjected to a pre-treatment with aqueous ethanol solution. The aim of the study was to investigate the phytochemical profile and bioactivity of the ethanol-wash solutes (EWS) obtained as a waste product of the main process of the protein isolate preparation from industrial rapeseed meal. Proximate composition analysis revealed that total carbohydrates were more than half of the product (60.63%). The content of hydrolysable reducing sugars was 44.13%, while glucose was 7.22%. The total phenols amounted 13.38%. EWS contained 1.63% total flavonoids and 242.05 µmol/g dry weight glucosinolates. The major components, as determined by GC–MS analysis, were sucrose, turanose and melibiose with 22.68%, 4.08% and 3.97% of total ion current (TIC) of polar compounds, respectively; cetyl alcohol (2.45% of TIC) and methyl oleate (2.08% of TIC) representing nonpolar compounds, and sinapic acid (73.71% of TIC) which was the prevailing substance of the phenolic acids identified in the EWS. The 0.2% EWS, prepared in aqueous 70% ethanol solution, exhibited 70.68% scavenging capability of DPPH radicals and 585.11 µmol Fe2+/g EWS (dry weight) reducing capacity. The product demonstrated limited antibacterial but broad antifungal activity which was expressed against Aspergillus niger (ATCC 1015), Aspergillus flavus, Penicillium sp., Rhizopus sp. and Fusarium moniliforme (ATCC 38932) as determined by the agar-well diffusion assay. Overall, EWS exhibited bioactive capacity, which revealed its potential application as a value-added product in the food and nutraceutical industries or agriculture. The broad-spectrum antifungal activity makes the product a prospective agent for food biopreservation or plant bioprotection.

Effective valorization of bio-processed castor kernel meal based fish feed supplements concomitant with oil extraction processing industry: A prolific way towards greening of landscaping/environment

The prime demand for expansion of feed-based aquaculture is the quest for new protein-rich ingredients to accomplish the global food and nutritional securities. Simultaneously, consistent production of agro-industrial wastes and their disposal is a major issue, although, the better nutritional profile of these wastes fostering a way forward to valorize in animal/fish feed. The present study was proposed to ensure the valorization of the castor oil industry’s residues i.e. castor cake or meal by standardizing the process for the preparation of protein isolate with the help of iso-electric precipitation method and subsequently utilizing them in fish feed. Maximum recoveries and protein content (P<0.05) for the castor protein isolate (CPI) were achieved at 12.0/5.0 pH combination. The nutritional quality of the protein isolate (CPI) was superior to the kernel meal and comparable to standard protein (egg white) and soybean protein isolates (SPI). In vivo evaluation of CPI was carried out in Labeo rohita fingerlings by feeding the different graded dietary level of CPI with substitution of 0%, 25%, 50%, 75%, and 100% soybean protein isolate based on equivalency of the protein. The diets were designated as control, CPI 25 , CPI 50 , CPI 75 , CPI 100 , respectively. The CPI contributed 0%, 11.83%, 22.78%, 33.28% and 43.91% of the total protein in experimental diets. Dietary castor protein isolate significantly affected the growth rate, feed conversion and nutrient utilization indices in L. rohita fingerlings. Maximum observed growth indices were in fish fed with control and CPI 25 , CPI 50 , and CPI 75 diets whereas, minimum in CPI 100 fed group. Dietary CPI did not affect the body indices, survival and body composition in rohu fingerlings. Based on the results, it can be concluded that castor protein isolate would be a valuable protein-rich ingredient for fish feed and 75% substitution of soy protein isolate with castor protein isolate could be possible without any harmful effects on growth, feed conversion, nutrient utilization and survival. • The method for preparation of castor protein isolate (CPI) was standardized. • The pH condition of 12.0/5.0 exhibited the best recoveries and protein content of CPI. • The nutritional value of CPI was superior to meal and comparable to egg white. • 75% substitution of soy protein isolate (SPI) with CPI is possible in carp diet. • CPI would be a potential protein source in animal/fish feed.

Effect of heat pretreatment before isoelectric solubilisation/precipitation on the characteristics of Pacific oyster (Crassostrea hongkongensis) and Antarctic krill (Euphausia superba) protein isolates

SummaryHeat treatment is a convenient way to eliminate the effects of endogenous enzymes on the industrial production of stable products. This study describes the preparation of protein isolates from oysters (OPI and HOPI) and krill (KPI and HKPI) by isoelectric solubilisation/precipitation (ISP) with or without heat pretreatment and comparatively presents their characteristics. The results showed that the solubilities of HOPI (24.08 ± 1.94%) and HKPI (42.29 ± 0.78%) were higher than those of OPI (13.46 ± 0.78%) and KPI (21.71.46 ± 1.51%), and the free and total sulphhydryl (‐SH) content and surface hydrophobicity of HOPI and HKPI were higher than those of OPI and KPI, which are related to higher fat content of HOPI (10.37 ± 0.55%) and HKPI (34.89 ± 1.19%). SDS–PAGE and gel chromatography pattern results showed that macromolecular proteins were degraded by endogenous enzymes in OPI and KPI, while they remained unaffected in HOPI and HKPI. The FT‐IR spectra showed similar patterns between OPI and HOPI and between KPI and HKPI. While the essential amino acid content was similar for OPI and HOPI (47.06 ± 1.33% and 47.93 ± 1.02%), that of KPI and HKPI (50.89 ± 0.89% and 51.19 ± 1.11%, respectively) was not significantly different.

Distribution and degradation of DNA from non-genetically and genetically modified soybean (Roundup Ready): Impact of soybean protein concentrate and soybean protein isolate preparation

To improve genetically modified product labelling legislation and promote the development of genetically modified foods, the mass variations of genomic DNA and length distributions of DNA fragments in non-genetically and genetically modified soybean (Roundup Ready) and the variations in transgenic contents during soybean protein concentrate (SPC) and soybean protein isolate (SPI) preparation were monitored. The material masses throughout the process conformed to the law of mass conservation, and amounts of DNA recovered decreased with SPC and SPI preparation. The successive steps of ethanol extraction led to a decrease in the size distribution of the recovered DNA. For the LECTIN and CP4 EPSPS targets investigated, longer fragments (>800 bp) were more affected than smaller fragments (<200 bp), and both targets degraded slowly upon degradation into small fragments. DNA distribution and degradation thereby affected GMO quantification. After preparation procedures, the transgenic contents of SPC and SPI products were higher than that of raw soybean.

Functional properties of the protein isolates of hyacinth bean [Lablab purpureus (L.) Sweet]: An effect of the used procedures

This study investigated the effect of protein isolate preparation procedures on functionality and characterization of protein isolates using salt-extraction dialysis, micellization and isoelectric precipitation. Micellization produced the highest protein content and yield (87.78 and 72.60 g/100g) followed by isoelectric precipitation and salt-extraction dialysis. Isoelectric precipitation gave a significantly higher digestibility (88.47 g/100g) than micellization and salt-extraction, as well as higher water and oil holding capacities (2.48 and 2.99 g/g). However, emulsion capacity (88.89–100%) and stability (20.15–37.00%) were not found to be significantly affected by the extraction method. Salt-extraction gave the highest foaming capacity but lowest foaming stability (123.33 and 27.32%) than isoelectric and micellization precipitation. Isoelectric and micellization precipitation gave better gelling abilities (16%) than salt-extraction. Arginine and lysine contents of isolates were high (12.70–16.59) with protein efficiency ratios for the isolates greater than 2 (2.61–6.66), indicative of a high protein quality. Protein isolates may be useful in supplementing foods that require improved functionality and protein qualities, but extraction procedures play a significant role in the functional properties of the final product.

Characterization of Vicia ervilia (bitter vetch) seed proteins, free amino acids, and polyphenols.

Vicia ervilia is an ancient crop from the Mediterranean Region. It may represent a useful source of proteins for food and animal feed, as well as bioactive components. Seed samples from 39 populations of V. ervilia have been analyzed. Polyphenol contents ranged from 0.09% to 0.19%. Luteolin, kaempferol, apigenin, and quercetin were the major aglycones. The total free amino acid content of the seeds was 0.05% to 0.19% in which canavanine represented 9% to 22%. The protein content was 24.1%. The amino acid composition indicated a high content in acidic amino acids and a deficit in sulphur amino acids. V. ervilia seeds proved to be a good substrate for the preparation of protein isolates. The seed extracts inhibited the proliferation of Caco-2 colon tumor cells, simultaneously, exerting antioxidative effects. Hence, seeds of V. ervilia could represent a source of high-value food and feed components, as well as functional components. PRACTICAL APPLICATIONS: Vicia ervilia (bitter vetch) (Leguminosae) is an ancient crop from the Mediterranean Region. Although it was still grown in many Mediterranean countries at the beginning of the twentieth century, other crops that provide higher and more consistent yield later replaced it. However, V. ervilia seeds may represent a useful source of proteins for human nutrition and animal feeding, and a source of bioactive components with health-promoting properties. Our results show that the seeds of V. ervilia could, indeed, represent a source of high-value food and feed components, as well as functional, health-promoting components. This may result in a revalorization of this neglected crop. The availability of numerous populations in seed banks guarantees the preservation of a genetic diversity in V. ervilia that could be used for the production of new varieties with better nutritional and functional characteristics.

Nutraceutical protein isolate from pigeon pea (Cajanus cajan) milling waste by-product: functional aspects and digestibility.

The aim of the present study was to utilize the protein from pigeon pea milling waste by-product for the preparation of protein isolate (PPI). The PPI was exposed to pepsin hydrolysis to reveal functional aspects like increased antioxidant capacity along with gelling ability. Complexation study demonstrated the use of PPI as an encapsulating material for water insoluble bioactive compounds (curcumin). Fluorescence spectroscopy revealed the formation of a complex through hydrophobic interaction. Ex vivo digestibility of the major proteins of PPI resulted in many peptides after digestion with human gastrointestinal enzymes. The peptide sequences identified may have potential biological activities, as revealed by bioinformatic data analysis. The presence of bioactive peptides and essential amino acids in the ex vivo digest suggests the role of PPI as a nutraceutical protein. The study provides a new value addition to pigeon pea milling waste by-product, a novel nutraceutical protein that can be used in functional food formulations.

Functional properties of chickpea protein isolates dried by refractance window drying

In the present study, the effect of Refractance Window (RW) drying on the functional properties of chickpea protein isolates was investigated and compared to freeze drying at different pH levels. The functional properties investigated were protein solubility, water and oil holding capacity, emulsifying properties, foaming properties, flocculation and coalescence indices and textural properties. The solubility, oil holding capacity and foam stability of the freeze dried protein isolates were determined to be higher than the RW dried samples. On the other hand, the RW dried samples had better water holding capacity and emulsion stability compared to the freeze dried protein isolates. The emulsion activity index, flocculation and coalescence indices of the chickpea protein isolates prepared by different drying techniques showed different tendencies depending on the pH level. Freeze dried protein isolates exhibited higher gelation ability than RW dried samples according to the texture profile analysis. This study clearly showed that the drying technique used in the preparation of protein isolates can affect their functional properties.

Functionality and Biological Activity of Isolate Processed Water Generated During Protein Isolate Preparation of Fish Roes Using an Isoelectric Solubilization and Precipitation Process

Functionality and Biological Activity of Isolate Processed Water Generated During Protein Isolate Preparation of Fish Roes Using an Isoelectric Solubilization and Precipitation Process

STUDYING THE FACTORS EFFECTING THE PRODUCTION OF OKRA PROTEIN CONCENTRATE AND ISOLATE AND THEIR THERMAL PROPERTIES

The current study was included the use of okra seeds (Abelmoschus esculentus) for preparation of Defatted Okra Powder (DOP), Okra Protein Concentrate (OPC) and Okra Protein Isolate (OPI). Three methods were used to identify the best one for protein concentrate preparation . The concentrate with 72.1% protein was prepared by removal of seed peel, ground, defatting and treated with ethanol. The optimum conditions for protein isolate preparation were 1:40 (water: DOP), extraction time of 75 minutes, extraction pH 9.0 and the precipitation pH was 4.0. This study also investigated the chemical composition to products that were 50.8,72.1,91.2% protein ,0.88,0.86,0.32 % fat ,8.45,9.94,2.67% ash and 35.23,12.37,3.26% carbohydrates For each of DOP ,OPC and OPI respectively. The amount of energy required for protein denaturation were 1.193, 0.5325, 0.236 J / g for DOP , OPC and OPI respectively.

Amino Acid Profiles of 44 Soybean Lines and ACE‐I Inhibitory Activities of Peptide Fractions from Selected Lines

AbstractSoybeans are cultivated in the United States chiefly for cooking oil, while the residue after oil extraction (soybean meal) is mostly used in animal feed formulations. High protein content in the defatted soybean meals led to the extraction of pure protein and its application in food products. We selected 44 soybean lines to determine their moisture and protein contents, and their amino acid composition was investigated. Soybean lines with high protein content, one high yielding (R95‐1705), and two high oleic acid (N98‐4445A, S03‐543CR), were selected for protein isolate preparation, hydrolysis using alcalase and gastro‐intestinal (GI) resistance. Furthermore, the GI resistant hydrolysates were fractionated and tested for angiotensin‐I‐converting enzyme (ACE‐I) inhibition activity. The amino acid analysis showed high methionine in the high protein and fatty acid lines (R05‐4494 and R05‐5491), and high cysteine content in one of the high oleic acid soybean line CRR05‐188 in comparison to the check lines (UA‐4805 and 5601‐T). The protein isolate with the highest purity (90–93 %) was derived from the selected lines N98‐4445A and S03‐543CR, and hydrolyzed using alcalase enzyme. The protein hydrolysates (500 µg/mL) showed inhibition of the ACE‐I by 49 %. The results from this study will promote the use of high oleic acid soybeans as a source of protein and peptides with functional activities.

Evaluation of SDS depletion using an affinity spin column and IMS‐MS detection

While the use of detergents is necessary for a variety of protein isolation preparation protocols, they are not compatible with mass spectral analysis due to ion suppression and adduct formation. This manuscript describes optimization of detergent removal, using commercially available SDS depletion spin columns containing an affinity resin, providing for both increased protein recovery and thorough SDS removal. Ion mobility spectrometry coupled with mass spectrometry (IMS-MS) allowed for a concurrent analysis of both analyte and detergent. In the case of both proteins and peptides, higher detergent concentrations than previously reported provided an increase of sample recovery; however there was a limit as SDS was detected by IMS-MS at higher levels of SDS indicating incomplete detergent depletion. The results also suggest that optimal conditions for SDS removal are dependent on the sample concentration. Overall, this study provides a useful guide for proteomic studies where SDS is required for efficient sample preparation.

Utilization of wild apricot kernel press cake for extraction of protein isolate

The kernels of apricot (Prunus armeniaca) stones are utilized for extraction of oil. The press cake left after extraction of oil was evaluated for preparation of protein isolate for its use in food supplementation. The apricot kernels contained 45-50% oil, 23.6-26.2% protein, 4.2% ash, 5.42% crude fibre, 8.2% carbohydrates and 90mg HCN/100g kernels, while press cake obtained after oil extraction contained 34.5% crude protein, which can be utilized for preparation of protein isolates. The method standardized for extraction of protein isolate broadly consisted of boiling the press cake with water in 1:20 (w/v) ratio for 1h, raising pH to 8 and stirring for a few min followed by filtration, coagulation at pH4 prior to sieving and pressing of coagulant for overnight and drying followed by grinding which resulted in extraction of about 71.3% of the protein contained in the press cake. The protein isolate contained 68.8% protein, 6.4% crude fat, 0.8% ash, 2.2% crude fibre and 12.7% carbohydrates. Thus the apricot kernel press cake can be utilized for preparation of protein isolate to improve the nutritional status of many food formulations.

ORIGINAL ARTICLE: Application of soybean meal, soy protein concentrate and isolate differing in α-galactosides content to low- and high-fibre diets in growing turkeys

The aim of this experiment was to investigate the physiological and growth response of young turkeys (up to 8 weeks of age) to dietary replacement of soybean meal (SBM) by soy protein concentrate (PC) or protein isolate (PI). This replacement resulted in a differentiated dietary concentration of α-galactosides of over 2.5% in the SBM diet, approximately 2% with a mixture SBM and PC, 1% with a PC diet and 0.1% with a PI diet. Each treatment was applied in two ways: with lower (3.5%) or higher (5.3%) dietary crude fibre content, made by supplementation with soybean hulls. The highest and lowest body weight of turkeys was recorded both after the first and second 4-week half of the study in the PC and PI-type diets respectively. A gradual withdrawal of α-galactosides from a diet was accompanied by a decline in ileal tissue mass, ileal viscosity and activity of endogenous maltase (the latter was found to be significant at 4 weeks of age). At the same time, two-way anova revealed that an elevated level of crude fibre (HF treatment) caused an increase in ileal tissue mass (p < 0.05 after 4 weeks of feeding) as well as a decrease in activity level of intestinal sucrase and maltase. The presence of raffinose family oligosaccharides in a diet, in contrast to dietary crude fibre level, significantly affected the caecal metabolism. The rate of bacterial production of short-chain fatty acids in the caeca was distinctly diminished by dietary withdrawal of α-galactosides. In conclusion, the soy protein concentrate, in contrast to the protein isolate preparation, exerted positive effects on the turkeys' growth and gastrointestinal tract physiology and should be considered as an effective SBM substitute.

Chickpea protein isolates obtained by wet extraction as emulsifying agents

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). 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. 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.

Propriedades funcionais das proteínas de amêndoas da faveleira (Cnidosculus phyllacanthus (Mart.) Pax. et K. Hoffm.) com e sem espinhos

The seed kernel of faveleira plant is a potential source of edible oil and proteins. The plant grows in all the northeastern states of Brazil, mainlly in the sertao (backlands) and caatinga regions. With an objective of its use in food formulations, the functional properties of the protein isolates of the kernel from the faveleira plants with (FCE) or without thorns (FSE) were studied. The kernels presented high lipid (40.56 and 40.21%) and protein (33.0 and 35.77%) content which increased to about 57.55 and 63.0% respectively after the lipid removal. In the preparation of protein isolates, the content of protein extraction was 83.5% for FCE and 80.57% for FSE at pH 10.5 while the protein recovery through isoelectric precipitation at pH 4.5 was 72.84 and 72.11%, respectively. The protein solubility index and the emulsification properties presented pH dependence with minimum values at isoelectric pH and maximum value at the extreme acidic and basic pHs. The protein isolate FSE showed better water and oil absorption capacities than FCE. The emulsion capacity and emulsion stability of both isolates presented appropriate performance in acidic and alkaline pH.

Composition and Functional Properties of Lupinus campestris Protein Isolates

Protein isolates from L. campestris and soybean seeds were prepared using isoelectric precipitation (PI) and micellization (MI) procedures. The amount of protein recovered was considerably higher with the isoelectric precipitation than with the micellization procedure (60% and 30%, respectively). Protein contents were higher than 90% in protein isolates. Antinutritional factors content (alkaloids, lectins, and tannins) were reduced to innocuous levels after protein isolate preparation. Minimum protein solubility for the precipitated lupin protein isolate (LPI) was at pH 4.0, and between pH 4 and 6 for the micellized lupin protein isolate (LMI), increasing at both extremes of the pH scale. Water absorption for the LMI was 1.3 ml/g of protein and its oil absorption 2.2 ml/g of protein. The LPI had 1.7 ml/g of protein in both water and oil absorption. Foaming capacity and stability was pH-dependent. Foaming capacity was higher at pH 2 and lower near the protein isoelectric points. Minimum protein concentration for gelation in LMI was 8% w/v at pH 4, while for LPI was 6% at pH 4 and 6. Amino acid composition in L. campestris flour and protein isolates was high in lysine and low in methionine. Most of the essential amino acids in lupin protein isolates were at acceptable levels compared to a reference pattern for infants and adults. The electrophoretic pattern of both protein isolates showed three bands with different mobilities, suggesting that the protein fractions belong to alpha-conglutin (11S-like protein), beta-conglutin (7S-like protein) and gamma-conglutin. It is proven that some of the functional properties of L. campestris protein isolates are similar to those soybean protein isolates recovered under equal conditions.