Lupin Protein Isolate Research Articles

ACE-inhibitory activity of enzymatic protein hydrolysates from lupin and other legumes

The objective of this investigation was to compare the angiotensin converting enzyme (ACE)-inhibitory activity of the hydrolysates obtained by pepsin digestion of proteins of some legumes, such as chickpea, common bean, lentil, lupin, pea, and soybean, by using the same experimental procedure. The ACE-inhibitory activity was measured by using the tripeptide hippuryl-histidyl-leucine (HHL), as model peptide, and HPLC-DAD, as analytical method. The peptide mixtures of all legumes were active, with soybean and lupin the most efficient, with IC50 values of 224 and 226μg/ml, respectively. Considering the promising results obtained with lupin, and aiming to identify the protein(s) that release(s) the peptides responsible for the activity, the peptides obtained from the pepsin digestion of some industrial lupin protein isolates and purified protein fractions were tested. The most active mixture, showing an IC50 value of 138μg/ml, was obtained hydrolysing a mixture of lupin α+β conglutin.

Functional Properties of Cowpea (Vigna Ungiculata L.Walp), and Lupin (Lupinus Termis) Flour and Protein Isolates

Chemical composition and functional properties of legume seed flours and protein isolates prepared by isoelectric precipitation procedure (A) and micellization procedure (B) were investigated. Cowpea (Vigna ungiculata L.) Protein Isolates (CPIA, CPIB) and Lupin (Lupinus termis) Protein Isolate (LPIA, LPIB) were prepared from dehulled defatted seeds. Proximate analysis gave 26.73-43.57% protein, 2.30%-9.75% fat, 3.87%-3.16% total ash, 1.02%-12.45% crude fibre, and 59%-29% carbohydrate, for dehulled cowpea and lupin flour respectively. The protein percentage of isolates was found to be 75%-76% in (CPIA and CPIB) while 91%-87% for LPIA and LPIB, respectively. The minimum protein solubility for CPIA was at pH 5.0 and for CPIB at pH 4.0. Protein solubility values of LPIB were higher than that of LPIA. Protein isolates showed good solubility in all pH ranges. For water and oil absorption capacity, Dehullued Cowpea Flour (DCF) gave 1.30 ml water/g sample and 1.04 ml oil/g sample respectively; while CPIA 2.10 ml water/g sample and 1.93 ml oil/g sample, CPIB 2.33 ml water/g sample and 2.37 ml oil/g sample. Dehullued Lupin Flour (DLF) gave 1.80 ml water/g sample and 1.80 ml oil/g sample. However, LPIB had higher oil absorption capacity than LPIA. The highest Emulsifying Capacity (EC) was observed at pH 12.0 for Dehullued Defatted Cowpea Flour (DDCF) (173 oil/g protein), for CPIA (160 oil/g protein) while CPIB showed highest EC (137 oil/g protein) at pH 2.0. The EC for both (CPIA and CPIB) was higher at pH 7.0 compared to value obtained from DDCF. In fact, LPIB had higher fat absorption and emulsification capacity than LPIA. The least gelation concentrations for studied legume flours and protein isolates were noted at 12.0% (w/v).

Characterisation of volatile compounds of lupin protein isolate‐enriched wheat flour bread

The influence of lupin protein isolate (LPI) on the volatile fraction of wheat flour (WF) bread was investigated. Headspace solid-phase microextraction technique (HS-SPME) coupled to the gas chromatography–mass spectrometry (GC–MS) analysis was applied to characterise volatile compounds of both crust and crumb. In a preliminary sensory experiment, LPI was found to have a modifying effect on the odour of WF-bread. The most important odorants of WF and LPI-containing wheat flour (LWF) breads were evaluated on the basis of detection frequency analysis. Fifty three compounds were detected by more than five judges, ten of which were detected only in LWF bread. The most important compounds of LPI-containing crumb and crust were vinylpyrazine, hexanal, 2-propylpyrazine, 2-octenal, 2,3-butanedione, 2,5-dimethylpyrazine, non-identified compounds with green, mushroom-like or pleasant odour and pyrazines. Their presence was attributed either to oxidative degradation of fatty acids or thermal reactions. Most of these compounds contributed to the aroma character of LPI-bread with green, earthy, malty, buttery and roasted notes.

Cholesterol-lowering effect of whole lupin (Lupinus albus) seed and its protein isolate

This study describes the hypocholesterolaemic effect of whole lupin and its protein in hamsters. The diets were: casein (control group HC), lupin protein isolate (group HPI) and whole lupin seed (group HWS). Diets from HPI and HWS promoted a significant reduction of total cholesterol and non-HDL cholesterol in the hamsters’ plasma as compared with HC. The true digestibility of HPI and HC groups were similar and differed significantly from the HWS one, which in turn showed a significant difference in total sterol excretion as compared to the former groups. Histological analysis of the liver revealed that animals fed on HPI and HWS diets presented a low level of steatosis (level 1) as compared to the ones fed on HC diet (level 4). Our findings demonstrate that protein isolate from Lupinus albus from Brazil has a metabolic effect on endogenous cholesterol metabolism and a protector effect on development of hepatic steatosis.

Foaming activity of lupin protein isolates in the absence of insoluble protein aggregates

This study investigates the foaming properties of two lupin protein isolates (LPIs) extracted by ultrafiltration (albumin-rich fraction; LPTF) and isoelectric precipitation (globulin-rich fraction; LPTE), respectively. An earlier work on LPIs extracted by similar methods, Alamanou and Doxastakis [1], blamed the insoluble protein aggregates for the worse foamability and foam stability of the LPTE isolate compared to the LPTF isolate. Herein, the foaming properties of LPI are examined after removal of the insoluble fraction in order to appraise solely the effect of dissolved proteins. Foams are produced by whipping 1% w/v of LPIs aqueous solutions at pH 5.5 and 7, alone but also with addition of xanthan gum (0.05% and 0.1% w/v) and NaCl (0.1 M). Foaming ability and stability are assessed globally by volumetric measurements and locally by electrical conductance measurements taken non-intrusively at different heights along the foam. Both LPIs showed satisfactory foaming activity with electrical measurements depicting local drainage features that global volumetric measurements could not capture. It is found that LPTF yields better foamability than LPTE, exactly as it was shown earlier in the presence of aggregates. However, there is a discrepancy with that earlier work regarding foam stability since the two isolates perform comparably in the absence of aggregates. The discrepancy may be explained by considering that the larger size LPTE aggregates could have a stronger destabilizing effect than the smaller size LPTF aggregates. The role of pH, xanthan gum and NaCl in affecting the performance of the two LPIs is also discussed.

Dough rheology and baking performance of wheat flour–lupin protein isolate blends

The impact of addition of two lupin protein isolates (LPI), enriched either in proteins belonging to globulin (LPI G) or to albumin (LPI A) fraction, on wheat flour dough and bread characteristics was investigated. LPI addition increased the dough development time and stability plus the resistance to deformation and the extensibility of the dough. The presence of LPI proteins in dough affected bread quality in terms of volume, internal structure and texture, while extra gluten addition to the blends to compensate for wheat gluten dilution, resulting from LPI addition, led to an improvement of bread quality characteristics. Generally, the incorporation of LP isolates to wheat flour delayed bread firming. The results obtained are discussed in terms of a possible action of LPI particles as a filler of the gluten network and partly in terms of possible interactions that take place between the gluten protein constituents and those of lupin.

The effects of various processing conditions on a protein isolate from Lupinus angustifolius

Lupin protein is a promising ingredient in functional foods because of its purported hypocholesterolaemic and hypotensive activities. In this study a lupin protein isolate from Lupinus angustifolius was thermally and mechanically treated and the effects on its protein profile were determined. As a preliminary step, the main protein components of L. angustifolius were identified, using the canonical proteomic approach, including 2D-separation and mass spectrometry and, whenever necessary, also “ de novo peptide sequencing”. Most of the main spots were assigned to the major lupin storage proteins: α-conglutin, β-conglutin, γ-conglutin, and δ-conglutin. The protein degradation induced by the different treatments was studied via differential scanning calorimetry (DSC), 2D-electrophoresis, and mass spectrometry, in order to get the fingerprint of the intact peptides after processing. The results indicate that, even after harsh industrial processing, α-, β- and δ-conglutin are still able to release stable peptides, although they are completely or partially degraded, as shown by the 2D protein profiles and the DSC graphs.

In vivo (rat) and in vitro (Caco-2 cells) absorption of amino acids from legume protein isolates as compared to lactalbumin or casein

The amino acid absorption from legume protein isolates (from chickpeas, CPI; and lupins, LPI) was studied in in vivo and in vitro experiments in comparison to animal proteins (casein and lactalbumin). In the in vivo experiment on rats, the diets were isoenergetic and isonitrogen (per kg diet 15.5 MJ digestible energy and 150 g protein, respectively). At 150 min after feeding, the concentration of free amino acids in arterial and portal blood plasma of rats fed legume proteins was significantly different (p < 0.05) from rats fed animal protein (lactalbumin). In arterial plasma the concentration for Met, Leu, Trp and Lys in rats fed legume proteins was lower than lactalbumin controls and for Val and Cys higher; in portal plasma, the concentration of free Met, Leu, Trp and Lys was lower, and the concentration of Cys was higher in rats fed legume proteins than in rats fed lactalbumin. The cumulative (total mM at 195 min after ingestion) and net absorption (% of ingested amounts) of Met, Leu, Trp and Lys were higher (p < 0.01) for rats fed lactalbumin as compared to those fed legume protein isolates or casein. In the in vitro study (Caco-2 cell monolayers), after 2 h incubation the transport values of all the individual amino acids in CPI and LPI, except for Glu, Val and Ile, were lower (p < 0.01) than for casein or lactalbumin. The results indicate that amino acids from chickpea and lupin protein isolates are absorbed at slower rates than those from animal proteins, which might explain the lower nutritional utilisation of legume storage proteins as compared with lactalbumin or casein.

Lupin protein isolate and cysteine-supplemented casein reduce calcification of atherosclerotic lesions in apoE-deficient mice

Protein from lupin is supposed to have anti-atherogenic effects due to its lipid-lowering properties in laboratory animals. It is further suggested that the amino acid cysteine plays a crucial role in this aspect. The objective of the present study was to compare the effects of lupin protein and cysteine-supplemented casein with those of casein on atherosclerotic lesion development in apoE-deficient mice. For that purpose, thirty mice were fed an egg albumin-based Western-type diet containing test protein (100 g/kg) for 4 months. ApoE-deficient mice fed the lupin protein or the cysteine-supplemented casein had more than 50 % less aortic calcification than mice fed casein (P < 0.05). The quantified lesion area as a percentage of the total surface area, as well as the collagen and fat content of the lesions were not different between the three groups of mice. The concentration of VLDL TAG was higher in mice fed the lupin protein and the cysteine-supplemented casein than in mice fed casein (P < 0.05). The cholesterol concentrations of VLDL, LDL and HDL from mice fed the lupin protein and cysteine-supplemented casein were not different compared with the mice fed casein. Also, the plasma concentrations of homocysteine, Ca, inorganic phosphate, and the activity of glutathione peroxidase in plasma and liver did not differ between the three groups of mice. The present study shows that lupin protein and cysteine-supplemented casein compared with casein reduce the calcification of atherosclerotic lesions in apoE-deficient mice. This effect seems not to be mediated by effects on plasma lipoproteins, homocysteine and circulating minerals.

Antioxidant capacity and polyphenolic content of high-protein lupin products

In order to produce high protein lupin products, α-galactoside extraction from Lupinus angustifolius cv. Troll and cv. Emir and Lupinus albus cv. Multolupa, and protein isolation from L. albus cv. Multolupa were carried out. Trolox equivalent antioxidant capacity (TEAC), DPPH radical-scavenging activity (DPPH-RSA), peroxyl radical-trapping capacity (PRTC), superoxide dismutase-like activity (SOD-like activity), total phenolic compounds (TPC) and total flavonoids were determined in lupin products. In L. angustifolius cv. Troll, L. angustifolius cv. Emir and L. albus cv. Multolupa α-galactoside-low flours, the TEAC and DPPH-RSA decreased (43%, 38%; 73%, 82%; 77%, 38%, respectively). PRTC decreased in L. angustifolius cv. Troll and L. albus cv. Multolupa α-galactoside-low flours (13% and 98%, respectively), while in those of L. angustifolius cv. Emir, PRTC increased (25%). SOD-like activity and TPC were also affected by α-galactoside extraction and reductions of 30–52% and 38–56%, respectively, were observed. The protein isolate of L. albus cv. Multolupa presented lower TEAC (24%), a similar level of PRTC and twice higher level of DPPH-RSA than did α-galactoside-low Multolupa flour. Moreover, the SOD-like activity of lupin protein isolate was sharply reduced but the TPC content was 24% higher. The technological procedures, α-galactoside extraction and protein isolation, provide high protein lupin products but with lower antioxidant capacity and total phenolic compounds than the raw seeds, although the levels of antioxidant capacity of these lupin products resemble those of cereals.

Parameters for the evaluation of the thermal damage and nutraceutical potential of lupin‐based ingredients and food products

Foods based on sweet lupin proteins are gaining attention from industry and consumers because of their possible role in the prevention of cardiovascular disease. When promoting lupin-based foods for inclusion in a daily diet, the thermal damage suffered during processing is of relevance to the bioactive and nutritional quality of the food product. N-(2-furoylmethyl)-L-lysine (furosine) quantification demonstrates that currently available sweet lupin protein isolates have a thermal damage comparable to or lower than other traditional food ingredients, and are a good source of lysine in non-dairy products. In lupin-based foods claiming to have cholesterol-lowering potential, shotgun proteomics offers itself as a fast and effective screening method for assessing the biological availability of active peptides. Such a method is readily applicable to other legume-enriched food products.

Lupin (Lupinus albus) Protein Isolate (L-ISO) Has Adequate Nutritional Value and Reduces Large Intestinal Weight in Rats after Restricted and ad libitum Feeding

Background: A protein isolate from white lupin (Lupinus albus; L-ISO) has potential as a novel human food ingredient, but its nutritional effects are unknown. Methods: We evaluated protein quality and effects on body composition in rats of isoenergic diets of L-ISO, lactalbumin, or casein with both restricted (10-day) and ad libitum (28-day)intake. The diets were equivalent in protein per se, but supplementation was used to balance essential amino acid levels. Results: In both studies, the rats consumed similar amounts of each diet, and no effect of diet on the gain:feed ratio was observed – though gain:N ratio and net protein utilization were slightly lower for the L-ISO diet. Lower large intestinal weights after the L-ISO than after the lactalbumin diet were observed in both studies. The L-ISO diet resulted in lowered body fat percentage in the 10-day study but in an elevated level in the 28-day study. Liver composition (DNA, RNA, glycogen, and fat) and plasma levels of some amino acids (His, Thr, Ala, Pro, Tyr, Val and Met) were affected by diet, but no effects on plasma lipid, glucose, or uric acid were observed. Conclusion: The L-ISO diet did not affect feed intake and has adequate nutritional quality in rats whilst modifying large intestinal weight in a potentially beneficial manner – suggesting potential for this protein in human nutrition.

Improvement in food intake and nutritive utilization of protein from Lupinus albus var. multolupa protein isolates supplemented with ascorbic acid

The protein quality of protein isolates from lupin (LPI) ( Lupinus albus var. multolupa), prepared by isoelectric precipitation, was assessed by chemical analysis of protein and amino acids and biological analysis of digestive and metabolic utilization of protein by growing rats. The animals were fed isonitrogenous and isocaloric diets adjusted to meet their nutrient requirements, in which lupin protein isolate was the only protein source, complemented with 0.5% methionine. Different LPIs were prepared with addition, or not, of ascorbic acid as antioxidant. Protein isolates had a protein content of 87.8–98.1%. Manganese content of protein isolates was reduced by 72.8–89.5% compared to the raw seed flour. Results from in vivo experiments showed that addition of 0.5% ascorbic acid to LPI incorporated into diets led to a 82.8% increase in daily food intake, when compared to the non-supplemented LPI, reaching similar values to those obtained with a casein–methionine control diet. Digestive and metabolic utilization of protein from LPI, assessed by nitrogen absorption or apparent digestibility coefficient, and by nitrogen balance or percentage of retained to absorbed nitrogen, respectively, was high, when the dietary intake of animals fed the LPI diets was adequate after addition of 0.5% ascorbic acid, although slightly inferior to the values obtained with a casein–methionine control diet. The high nutritive utilization of protein was reflected in excellent growth and nutritional indices assayed. In conclusion, ascorbic acid supplementation led to an improvement in the palatability of the LPI diets and, therefore, in daily food intake, which was reflected in a higher nutritive utilization of protein and improvement in weight gain and the food transformation index.

Adsorption at the air–water interface and emulsification properties of grain legume protein derivatives from pea and broad bean

Functional properties of native and modified (through induced autolysis) pea ( Pisum sativum L.) and broad bean ( Vicia faba L.) protein derivatives are studied. In specific, protein solubility and behavior at the air–water interface through surface pressure measurements are investigated. Furthermore the ability of the protein products to act as emulsifying agents and to stabilize emulsions is studied through oil droplet size distribution measurements and by the protein adsorbed at the oil–water interface. The data reveal that the ability of the proteins to act as surfactants and build up a rigid film around the oil droplets, mainly depends on their suitable molecular configuration and structure. Hydrolysis did not promote the functionality of the legume proteins. Broad bean exhibited better functionality than pea, before and after hydrolysis. Some comparisons were also made with lupin ( Lupinus albus L.) protein isolate.

Preliminary approaches for the development of a high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry method for the detection and label‐free semi‐quantitation of the main storage proteins of Lupinus albus in foods

Since recent literature has indicated that white lupin (Lupinus albus) may be a useful source of hypocholesterolemic proteins to be used in functional food formulation, our final goal is the development of a fast and automated high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method for the detection and the label-free semi-quantitation of the main lupin globulins in lupin foods and food ingredients. We present here some preliminary results in this direction. As a first step a total protein extract (TPE-WF) from lupin flakes was pre-fractionated by anion-exchange chromatography and each fraction was digested with trypsin and analyzed by HPLC/ESI-MS/MS. Subsequently, the tryptic digest of TPE-WF was directly analyzed by HPLC/ESI-MS/MS without any pre-fractionation. Eventually, in order to test the applicability of the method to real samples, a lupin beverage and two lupin protein isolates were analyzed. Both Mascot and Spectrum Mill MS Proteomics Workbench software were used to identify the protein composition in these samples and Spectrum Mill was used also to test the possibility of developing a label-free semi-quantitation method based on peptide hits. Encouraging results were obtained especially in the detection of the hypocholesterolemic component beta-conglutin.

Technological properties and non-enzymatic browning of white lupin protein enriched spaghetti

Spaghetti was prepared by replacing semolina with different amounts of lupin protein, in order to increase the protein content. A detailed investigation of the rheological properties of the dough and the cooking quality of pasta was performed in comparison to standard semolina spaghetti. Moreover, the effect of the addition of lupin protein on non-enzymatic browning was evaluated by measuring ε-furoylmethyllysine (furosine) and 5-hydroxymethyl-2-furancarboxaldehyde (HMF), which are considered useful indices of semolina quality and pasta processing conditions. Dried spaghetti fortified with 5% of lupin protein isolate has a colour and rheological features comparable with the semolina sample and also the behaviour during cooking results to be satisfactory. As far as the thermal damage is concerned, the furosine values of fortified spaghetti differ only marginally from standard pasta and the percentage lysine loss is quite small (ranging from 12.1% to 15.7%).

We-P14:483 Evaluation of nutritional and biological properties of a lupin protein isolate in Sprague-Dawley rats

We-P14:483 Evaluation of nutritional and biological properties of a lupin protein isolate in Sprague-Dawley rats

Optimization of a Pilot-Scale Process for Producing Lupin Protein Isolates with Valuable Technological Properties and Minimum Thermal Damage

This paper describes a pilot process for obtaining protein isolates from white lupin seed with improved water solubility and technofunctional properties as well as reduced thermal damage. After a careful optimization of the process parameters, two valuable food ingredients were prepared: lupin protein isolate type E, with a useful emulsifying capacity, and lupin protein isolate type F, with a high capability of foam formation and stabilization. The spray-drying process was particularly critical for inducing some thermal damage, but a careful selection of the conditions permitted ingredients having only marginally impaired lysine bioavailability to be obtained. The reproducibility of the protein extraction process was tested on two different lupin varieties.

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.

Analysis ofLupinus albusStorage Proteins by Two-Dimensional Electrophoresis and Mass Spectrometry

A laboratory-prepared total protein extract (TPE) and a lupin protein isolate (LPI-E) produced in a pilot plant were submitted to a detailed two-dimensional (2DE) proteomic investigation. Recent findings have indicated that in an established rodent model of hyperlipidemia, moderate daily intakes of LPI-Es lead to a reduction of total and low-density lipoprotein cholesterol levels, and the knowledge of the actual composition of the protein sample used in that study is at the basis of further structure/action investigations. The experimental results indicate that the semi-industrial procedure used for the production of LPI-E damages only marginally the proteins. It does, however, cleave some disulfide bridges and induce mild proteolysis, as confirmed by the higher number of resolved protein spots in the low Mr and acidic pI region of the 2DE map. Out of 72 spots submitted to mass spectrometry and compared with available protein databases, 42 correspond to fragments of beta-conglutin, the 7S globulin of lupin, spanning between positions 37 and 495 of the protein sequence. Using the bioinformatic tool BlastP, these peptides were compared to the alpha'-subunit of beta-conglycinin, the 7S globulin of soybean, this being the most active hypocholesterolemic component of soybean protein, as shown by in vitro and in vivo experiments. At least 18 peptides derived from beta-conglutin, having a percentage identity higher than 50% and a similarity percentage higher than 70% vs the alpha'-subunit of beta-conglycinin, are likely candidates to be the biologically active components of lupin protein.