Optimization of a pilot-scale process for producing lupin protein isolates with valuable technological properties and minimum thermal damage

Use of supercritical CO2 to improve the quality of lupin protein isolate

Lupins are an excellent source of protein which can be used to obtain protein isolates with potential use in the food industry. Some studies use supercritical CO2 (SC-CO2) to defat legume flours, but no study analyzes the effect of applying this technology directly to the protein isolate. This article has proposed the use of SC-CO2 to improve lupin protein isolate (LPI) quality. SC-CO2 increased the LPI purity while reducing oil and other antitechnological factors (saponins and polyphenols). The treatment significantly improved the LPI color due to the elimination of the lipid fraction and lipophilic pigments (carotenoids). No changes in amino acid contents or chemical score were observed due to the SC-CO2. Finally, the treatment improved or did not affect the main LPI technofunctional properties. Therefore, SC-CO2 is a promising technique to enhance the quality of protein isolates, without affecting or improving their functional properties.

Optimization and Characterization of Lupin Protein Isolate Obtained Using Alkaline Solubilization-Isoelectric Precipitation

The trend in today's society is to increase the intake of vegetable protein instead of animal protein. Therefore, there is a concern to find new sources of alternative protein. In this sense, legumes are the main protein source of vegetable origin. Of all of them, lupins are the ones with higher protein content, although they are currently undervalued as an alternative for human consumption. In this sense, it is vital to characterize and obtain protein isolates from this legume, which satisfies the growing demand. Therefore, in the present work, the procedure for obtaining a lupin (Lupinus luteus) protein isolate (LPI), based on basic solubilization followed by isoelectric precipitation, has been optimized and validated. The optimized LPI, as well as the lupin flour, were subsequently characterized. The chemical composition, physicochemical, as well as the technofunctional properties of the LPI were analyzed. The results show that the proposed procedure had a high yield (23.19 g LPI/100 g flour) and allowed to obtain high-purity protein isolates (87.7 g protein/100 g LPI). The amino acid composition and the chemical scores show high proportions of essential amino acids, being protein deficient only in methionine and valine. Therefore, it can be affirmed that it is a high-quality protein that meets the requirements proposed by the FAO. Regarding the lipid fraction, it is mainly composed of unsaturated fatty acids (C18:1n-9 and C18:2n-6), which is also advisable in order to follow a healthy diet. Finally, LPI showed interesting technofunctional properties (foaming, gelling, emulsifying, water and oil absorption, and solubility), which makes it especially attractive for use in the food industry.

Design of Plant-Based Food: Influences of Macronutrients and Amino Acid Composition on the Techno-Functional Properties of Legume Proteins

Imitating animal-based products using vegetable proteins is a technological challenge that can be mastered based on their techno-functional properties. These properties of legume proteins can be influenced by multiple factors, among which the macronutrients and amino acid contents play an important role. Therefore, the question arises as to what extent the techno-functional properties are related to these factors. The water- and oil-holding capacities and the emulsion and foaming properties of commercially available legume protein powders were analyzed. Correlations between macronutrient, amino acid content, steric structure, and techno-functional properties were conducted. However, the protein concentration is the focus of techno-functional properties, as well as the type of protein and the interaction with the non-protein ingredients. The type of protein is not always quantified by the quantity of amino acids or by their spatial arrangement. In this study, the effects of the three-dimensional structure were observed by the used purification method, which overshadow the influencing factors of the macronutrients and amino acid content. In summary, both the macronutrient and amino acid contents of legume proteins provide a rough indication but not a comprehensive statement about their techno-functional properties and classification in an adequate product context.

White Lupine (Lupinus albus L.) Flours for Healthy Wheat Breads: Rheological Properties of Dough and the Bread Quality

Protein-based foods based on sweet lupine are gaining the attention of industry and consumers on account of their being one of the legumes with the highest content of proteins (28-48%). Our objective was to study the thermal properties of two lupine flours (Misak and Rumbo) and the influence of different amounts of lupine flour (0, 10, 20 and 30%) incorporations on the hydration and rheological properties of dough and bread quality. The thermograms of both lupine flours showed three peaks at 77-78 °C, 88-89 °C and 104-105 °C, corresponding to 2S, 7S and 11S globulins, respectively. For Misak flour, higher energy was needed to denature proteins in contrast to Rumbo flour, which may be due to its higher protein amount (50.7% vs. 34.2%). The water absorption of dough with 10% lupine flour was lower than the control, while higher values were obtained for dough with 20% and 30% lupine flour. In contrast, the hardness and adhesiveness of the dough were higher with 10 and 20% lupine flour, but for 30%, these values were lower than the control. However, no differences were observed for G', G″ and tan δ parameters between dough. In breads, the protein content increased ~46% with the maximum level of lupine flour, from 7.27% in wheat bread to 13.55% in bread with 30% Rumbo flour. Analyzing texture parameters, the chewiness and firmness increased with incorporations of lupine flour with respect to the control sample while the elasticity decreased, and no differences were observed for specific volume. It can be concluded that breads of good technological quality and high protein content could be obtained by the inclusion of lupine flours in wheat flour. Therefore, our study highlights the great technological aptitude and the high nutritional value of lupine flours as ingredients for the breadmaking food industry.

Quality and health dimensions of pulse-based dairy alternatives with chickpeas, lupins and mung beans

Health and environmental issues regarding dairy consumption have been highlighted in recent years leading to tremendous consumer demand for plant-based substitutes. In this review, we focused on quality and health dimensions of pulse-based dairy alternatives (PuBDA) using chickpeas, lupins and mung beans. Appraisal of existing documents show that there is limited information on PuBDA with the said pulses compared to similar materials such as soy and pea. Most of the studies focused on milk or fermented milks, either in full or partial substitution of the dairy ingredients with the pulses. Issues on stability, sensory properties, shelf life and nutritional quality were underlined by existing literature. Although it was emphasized in some reports the health potential through the bioactive components, there is scarce data on clinical studies showing actual health benefits of the featured PuBDA in this paper. There is also a scant number of these PuBDA that are currently available in the market and in general, these products have inferior nutritional quality compared to the animal-based counterparts. Technological innovations involving physical, biological and chemical techniques can potentially address the quality problems in the use of chickpeas, lupins, and mung beans as raw materials in dairy alternatives.

Combined Effect of Extraction and Purification Conditions on Yield, Composition and Functional and Structural Properties of Lupin Proteins

Lupin meal presents great potential as an alternative plant-based source of proteins for human nutrition. In the present work, different conditions of extraction and purification were evaluated for production of lupin protein isolates. The results showed that the protein extraction yield was comparable at acidic and conventionally used alkaline extraction pH (37% vs. 40–45%, respectively). Proteins extracted were principally composed of globulins. The ionic strength negatively impacted the protein extractability at pH 2, whereas no significant differences were observed between extractions at 20 to 50 °C. The selected extraction conditions (pH 2 and 7) combined with purification by isoelectric precipitation or ultrafiltration process generated the isolate-grade products. Interestingly, further characterization revealed a partial denaturation of proteins extracted at pH 2 resulting in loss of protein solubility at pH 6 and 7 (10–50%), modifications in secondary structure, lower thermal stability, and formation of protein aggregates. However, foaming and emulsifying properties were generally similar for almost all lupin isolates. Further investigation might be of interest with regard to the extraction behaviours and structural and functional properties of specific lupin protein fractions.

Lupin protein isolate improves insulin sensitivity and steatohepatitis in vivo and modulates the expression of the Fasn, Gys2, and Gsk3b genes

Although studies on lupin protein isolate (LPI) have indicated the presence of a preventive effect on insulin resistance (IR) and lipid disturbances, their influence on established pathological traits has received little attention. Here, we evaluated the in vivo effects of LPI on IR and steatohepatitis as well as its influence on genes involved in lipid and carbohydrate metabolism. We first induced IR and steatohepatitis in rats by maintaining them on a high-fat diet for 5 weeks. Thereafter, we administered LPI to the rats daily for 3 weeks. LPI improved insulin sensitivity (AUC: 6,777 ± 232 vs. 4,971 ± 379, p < .05, pre- vs. post-treatment values) and reduced glucose and triglyceride levels by one-third. In addition, LPI-treated rats exhibited attenuated steatohepatitis. At the molecular level, LPI treatment reduced liver Fasn gene expression substantially but increased Gys2 and Gsk3b levels. We concluded that the hypolipidemic and hypoglycemic activities of LPI may be caused by reduced liver lipogenesis and modulation of insulin sensitization mechanisms.

Lupin Protein Isolate Structure Diversity in Frozen-Cast Foams: Effects of Transglutaminases and Edible Fats

This study addresses an innovative approach to generate aerated foods with appealing texture through the utilization of lupin protein isolate (LPI) in combination with edible fats. We show the impact of transglutaminases (TGs; SB6 and commercial), glycerol (Gly), soy lecithin (Lec) and linoleic acid (LA) on the micro- and nanostructure of health promoting solid foods created from LPI and fats blends. 3-D tomographic images of LPI with TG revealed that SB6 contributed to an exceptional bubble spatial organization. The inclusion of Gly and Lec decreased protein polymerization and also induced the formation of a porous layered material. LA promoted protein polymerization and formation of homogeneous thick layers in the LPI matrix. Thus, the LPI is a promising protein resource which when in blend with additives is able to create diverse food structures. Much focus has been placed on the great foamability of LPI and here we show the resulting microstructure of LPI foams, and how these were improved with addition of TGs. New food applications for LPI can arise with the addition of food grade dispersant Lec and essential fatty-acid LA, by improved puffiness, and their contributing as replacer of chemical leavening additives in gluten-free products.

Rapid and Simultaneous Quantification of Five Quinolizidine Alkaloids in Lupinus angustifolius L. and Its Processed Foods by UPLC-MS/MS

Quinolizidine alkaloids (QAs) are toxic secondary metabolites of Lupinus plants. This study reports the simultaneous quantification of five alkaloids from Lupinus angustifolius L. and its processed foods by ultraperformance liquid chromatography with electrospray ionization mass spectrometric detection. After optimizing the extraction conditions, the analytical method was validated for the QAs in lupin beans and in three major processed foods through detection and quantification limits, linearity, precision, and accuracy. The detection and quantification limits of the QAs were 0.5-1.7 and 1.5-5.7 mg kg^-1, respectively. The linearity was greater than 0.9992 and the precision was less than 3.1%. The recoveries of three different concentrations of each QA were 89.5-106.2%. For both raw lupin beans and processed foods, lupanine was the major QA, and 13-hydroxylupanine and angustifoline were detected in lower amounts. This method could be widely used for accurate risk assessment of QAs.

Characterisation of the molecular interactions between primary bile acids and fractionated lupin cotyledons (Lupinus angustifolius L.)

Interactions between bile acids and plant-based materials, and the related feedback mechanisms in enterohepatic circulation, have been considered targets for lowering cholesterol. This study aimed to identify lupin compounds that interact with primary bile acids on molecular level. Lupin cotyledons were fractionated and bile acid adsorbing activities were investigated using in vitro digestion, equilibrium dialysis and kinetic analyses. Protein- and fibre-enriched fractions significantly (p ≤ 0.05) adsorbed chenodesoxycholic acids (up to 2.33 µmol/100 g DM). Alcohol purification showed that bile acid adsorption is independent of protein and fibre structures. Moreover, high adsorption was observed with an alcohol extract (6.97 µmol chenodesoxycholic acids/100 g DM) that was rich in phytochemicals, such as flavonoids (1842 mg/100 g DM). These results suggest the formation of hydrophobic interactions between polyphenols and bile acids. Further studies of molecular mechanisms are required to define the contributions of polyphenols to the cholesterol-lowering actions of lupins.

Techno-Functional, Nutritional and Environmental Performance of Protein Isolates from Blue Lupin and White Lupin

Similarly prepared protein isolates from blue lupin (Lupinus angustifolius) and white lupin (L. albus) were assessed in relation to their composition, functional properties, nutritional attributes and environmental impacts. Blue lupin protein isolate (BLPI) and white lupin protein isolate (WLPI) were found to be quite similar in composition, although differences in the electrophoretic protein profiles were apparent. Both lupin protein isolates (LPIs) had good protein solubility (76.9% for BLPI and 69.8% for WLPI at pH 7) and foaming properties. However, a remarkable difference in heat gelation performance was observed between BLPI and WLPI. WLPI had a minimum gelling concentration of 7% protein, whereas BLPI required 23% protein in order to form a gel. WLPI also resulted in stronger gels over a range of concentrations compared to BLPI. Nutritional properties of both LPIs were similar, with no significant differences in in vitro protein digestibility (IVPD), and both had very low trypsin inhibitor activity (TIA) and fermentable oligo-, di- and monosaccharides, and polyols (FODMAP) content. The amino acid profiles of both LPIs were also similar, with sulfur-containing amino acids (SAAs) being the limiting amino acid in each case. Environmental impacts revealed by the life cycle assessment (LCA) were almost identical for BLPI and WLPI, and in most categories the LPIs demonstrated considerably better performance per kg protein when compared to cow's whole milk powder.

Effect of Ultrasound Application on Protein Yield and Fate of Alkaloids during Lupin Alkaline Extraction Process

The objective of this work is to elucidate the fate of quinolizidine alkaloids (QA) during the lupin protein extraction process assisted with ultrasound and the evaluation of the nutritional and functional properties of the protein fraction. Proximal characterization, concentration of anti-nutritional compounds, amino acid profile and protein solubility profile of flours from three lupin species were (L. albus, L. angustifolius and L. mutabilis) assessed. The result showed a significant difference (p < 0.05) in protein concentration, fat, total alkaloids and particle size between the three species flours. Based on these parameters, the most different Lupinus species (L. mutabilis and L. angustifolius) were chosen to study the behavior of the protein fraction in terms of functionality, composition and resistance to thermal treatments. The results obtained for L. mutabilis described the ultrasound effect as beneficial for protein yield (14% more than control), QA reduction from bagasse (81% less than control) and protein isolate production (50% less than control). On the other hand, L. angustifolius was more resistant to the ultrasound effect with no significant difference between treatments (10 and 15 min) and control but with the lower toxicity and better amino acid score. These results will be useful to design processes to assist in the objective of meeting the future protein demand of the population.

Chemical and Nutritional Evaluation of Protein-Rich Ingredients Obtained through a Technological Process from Yellow Lupin Seeds (Lupinus luteus)

In recent years, interest in plant-based proteins has been rising due to ethical and sustainability issues. In this context, the production of protein concentrates and isolates from new plant sources have increased enormously because of their nutritional and techno-functional properties. Therefore, this work describes a pilot process for obtaining protein-rich ingredients from a yellow lupin variety (Lupinus luteus) developed by the Agriaquaculture Nutritional Genomic Center (CGNA). A protein alkaline solubilisation followed by isoelectric precipitation was used as a method for obtaining a protein concentrate (LPC) and isolate (LPI) with 75 and 95% protein, respectively. The changes in the protein quality and chemical composition during the protein concentration process from lupin flour were evaluated. Thus, nutritional parameters such as the amino acids (AAs) profile, essential amino acid index (EAAI), chemical score (CS), the protein efficiency ratio (PER), and digestible indispensable amino acid score (DIAAS) were determined to evaluate the nutritional quality of LPC and LPI. The facile and scalable protein isolation method without a defatting process proposed in this study showed a great protein separation efficiency (PSE), while the amino acids profile was not affected during both the concentration as well as the isolation of proteins. In addition, SDS-PAGE showed that both LPC and LPI mainly contained the high-molecular-weight proteins α and β-conglutins. Both LPC and LPI had a balanced amino acids profile, and arginine was the most predominant amino acid. These results are useful for increasing the use of lupin based-protein ingredients as a potential functional ingredient in the food industry.

In Vitro Interactions of Dietary Fibre Enriched Food Ingredients with Primary and Secondary Bile Acids

Dietary fibres are reported to interact with bile acids, preventing their reabsorption and promoting their excretion into the colon. We used a method based on in vitro digestion, dialysis, and kinetic analysis to investigate how dietary fibre enriched food ingredients affect the release of primary and secondary bile acids as related to viscosity and adsorption. As the main bile acids abundant in humans interactions with glyco- and tauroconjugated cholic acid, chenodesoxycholic acid and desoxycholic acid were analysed. Viscous interactions were detected for apple, barley, citrus, lupin, pea, and potato derived ingredients, which slowed the bile acid release rate by up to 80%. Adsorptive interactions of up to 4.7 μmol/100 mg DM were significant in barley, oat, lupin, and maize preparations. As adsorption directly correlated to the hydrophobicity of the bile acids the hypothesis of a hydrophobic linkage between bile acids and dietary fibre is supported. Delayed diffusion in viscous fibre matrices was further associated with the micellar properties of the bile acids. As our results indicate changes in the bile acid pool size and composition due to interactions with dietary fibre rich ingredients, the presented method and results could add to recent fields of bile acid research.

Differentiation of Adsorptive and Viscous Effects of Dietary Fibres on Bile Acid Release by Means of In Vitro Digestion and Dialysis

To explain the cholesterol-reducing effects of dietary fibres, one of the major mechanisms proposed is the reduced reabsorption of bile acids in the ileum. The interaction of dietary fibres with bile acids is associated with their viscous or adsorptive effects. Since these fibre characteristics are difficult to investigate in vivo, suitable in vitro methodologies can contribute to understanding the mechanistic principles. We compared the commonly used centrifugal approach with a modified dialysis method using dietary fibre-rich materials from different sources (i.e., barley, citrus, lupin, and potato). Digestion was simulated in vitro with oral, gastric, and small intestinal digestion environments. The chyme was dialysed and released bile acids were analysed by high-performance liquid chromatography. The centrifugation method showed adsorptive effects only for cholestyramine (reference material) and a high-fibre barley product (1.4 µmol taurocholic acid/100 mg dry matter). Alternatively, the dialysis approach showed higher values of bile acid adsorption (2.3 µmol taurocholic acid/100 mg dry matter) for the high-fibre barley product. This indicated an underestimated adsorption when using the centrifugation method. The results also confirmed that the dialysis method can be used to understand the influence of viscosity on bile acid release. This may be due to entrapment of bile acids in the viscous chyme matrix. Further studies on fibre structure and mechanisms responsible for viscous effects are required to understand the formation of entangled networks responsible for the entrapment of the bile acids.

Lupinus mutabilis: Composition, Uses, Toxicology, and Debittering

Lupinus mutabilis has protein (32.0-52.6 g/100 g dry weight) and lipid (13.0-24.6 g/100 g dry weight) contents similar to soya bean (Glycine max). The Ω3, Ω6, and Ω9 contents are 1.9-3.0, 26.5-39.6, and 41.2-56.2 g/100 g lipid, respectively. Lupins can be used to fortify the protein content of pasta, bread, biscuits, salads, hamburgers, sausages, and can substitute milk and soya bean. Specific lupin protein concentrates or isolates display protein solubility (>90%), water-absorption capacity (4.5 g/g dry weight), oil-absorption capacity (3.98 g/g), emulsifying capacity (2000 mL of oil/g), emulsifying stability (100%, 60 hours), foaming capacity (2083%), foaming stability (78.8%, 36 hours), and least gelation concentration (6%), which are of industrial interest. Lupins contain bitter alkaloids. Preliminary studies on their toxicity suggest as lethal acute dose for infants and children 10 mg/kg bw and for adults 25 mg/kg bw. However, alkaloids can also have medical use for their hypocholesterolemic, antiarrhythmic, and immunosuppressive activity. Bitter lupins can be detoxified by biological, chemical, or aqueous processes. The shortest debittering process requires one hour. This review presents the nutritional composition of lupins, their uses (as food, medicine, and functional protein isolates), toxicology, and debittering process scenarios. It critically evaluates the data, infers conclusions, and makes suggestions for future research.

Hypolipidaemic and anti-atherosclerotic effects of lupin proteins in a rabbit model

The biological activities of a protein isolate from lupin (Lupinus albus) were studied in a rabbit model of atherosclerosis. Focal plaque development was induced at both common carotid arteries by perivascular injury. After surgery, animals were fed three different diets for 90 d, all with 1% cholesterol, 15% SFA and 20% protein; the protein source was casein (CAS), lupin proteins (LUP) or 50% CAS+50% LUP (CAS+LUP). Lower cholesterolaemia was detected in the LUP v. the CAS group at 60 and 90 d of treatment (-40·3 and -33·5%, respectively; P<0·05). Cryosection analyses of the carotids indicated a significant reduction in focal lesion progression in the LUP v. the CAS group (-37·4%; P<0·05). In summary, in a rabbit model of atherosclerosis, a protein isolate from L. albus reduced cholesterolaemia and exerted a remarkable protective activity against atherosclerosis progression.

Isolated Conglutin γ from Lupin, but not Phytate, Lowers Serum Cholesterol Without Influencing Vascular Lesion Development in the ApoE-deficient Mouse Model

Conglutin γ and phytate are considered as potential biofunctional compounds of lupin protein isolate, but their impact on vascular health is unknown. This study aimed to investigate the effect of conglutin γ and phytate, respectively, on circulating levels of sterols, markers of cholesterol biosynthesis and minerals, and on the development and progression of aortic lesions in apoE-deficient mice. To this end, mice were fed a western diet with either casein (200 g/kg; served as a control), conglutin γ from L. angustifolius (200 g/kg) or casein (200 g/kg) supplemented with phytate (5 g/kg) for 16 weeks. Here we found that conglutin γ but not phytate was capable of reducing the circulating concentration of cholesterol. Plasma levels of desmosterol and lathosterol as markers of the cholesterol synthesis were not affected, and 7-dehydrocholesterol was even higher in mice fed conglutin γ than in mice fed casein or casein + phytate. All mice developed pronounced aortic lesions, but histological characterization of plaque area and composition showed no differences between the three groups of mice. Conclusively, conglutin γ exerts cholesterol-lowering effects but appears to have no anti-atherosclerotic properties in the apoE-deficient mice. Phytate neither affected plasma cholesterol nor aortic lesion development.

Lipoxygenase activity in different species of sweet lupin (Lupinus L.) seeds and flakes

Lipoxygenase (LOX)-catalysed degradation of polyunsaturated fatty acids is supposed to be a major cause of undesirable off-flavour development in legumes. In the present study, a photometric LOX assay including adequate sample workup was adapted to lupin seeds, kernels and flakes, respectively. Optimum reaction conditions were at pH 7.5 using a phosphate buffer concentration of 150 mmol l(-1) without the addition of sodium chloride. The LOX activities of different lupin species and varieties were compared. Significant variations among the species and varieties ranging from 50 to 1004 units mg(-1) protein were determined, being significantly lower than soybean LOX activity. Hulling and flaking of the seeds resulted in a 15% increase of LOX activity. In contrast to soy and other legumes, LOX from lupin only converted free fatty acids, whereas trilinolein and β-carotene were not oxidised. Consequently, according to the established classification, lupin LOX activity may be assigned to the LOX type-1, which, to the best of our knowledge, was demonstrated for the first time.

Lupin peptides lower low-density lipoprotein (LDL) cholesterol through an up-regulation of the LDL receptor/sterol regulatory element binding protein 2 (SREBP2) pathway at HepG2 cell line

Previous experiments in suitable animal models and in mild hypercholesterolemic individuals have shown that the consumption of lupin proteins may be useful for controlling total and low-density lipoprotein (LDL) cholesterol levels. With the objective of providing evidence that peptides deriving from the hydrolysis of lupin proteins may be responsible of the observed activities and for investigating the mechanism of action, HepG2 cells were treated with lupin peptides obtained by either pepsin (P) or trypsin (T) hydrolysis, and molecular and functional investigations were performed on the LDL receptor/SREBP2 pathway. For the first time, this paper provides experimental evidence that lupin peptides are able to interfere with the HMGCoAR activity, up-regulating the LDL receptor (136 and 84% vs the control for P and T peptides, respectively, at 1 mg/mL) and SREBP2 proteins (148 and 73% vs the control for P and T peptides, respectively, at 1 mg/mL) via the activation of PI3K/Akt/GSK3β pathways and increasing the LDL uptake at HepG2 cell line (40 and 50% vs the control for P and T peptides, respectively, at 1 mg/mL). These results may be useful in explaining the activities observed in vivo in animals and humans treated with lupin protein.

Quality of Lupinus albus L. (white lupin) seed: extent of genotypic and environmental effects

White lupin seed can be used for traditional and functional foods or as animal feed. This study aimed to support lupin breeders and production stakeholders by assessing the extent of genotypic, environmental, and genotype × environment (GE) interaction effects on seed contents of oil, tocopherols (TOC), and quinolizidine alkaloids (QA), grain yield, and seed weight of eight elite genotypes grown in two climatically contrasting Italian locations for two cropping years. On average, plants in the subcontinental climate site exhibited higher grain yield and seed size, about 8% lower oil content, and almost 85% higher QA content than those in the Mediterranean climate site. The range of genotype means was 2.97-5.14 t/ha for yield, 92-110 mg/g for oil, and 0.121-0.133 mg/g for TOC. TOC amount was largely unpredictable and featured large GE interactions that hinder its genetic improvement. Oil and alkaloid contents and seed size are more predictable and offer potential for selection.

Consuming a mixed diet enriched with lupin protein beneficially affects plasma lipids in hypercholesterolemic subjects: a randomized controlled trial

BACKGROUND & AIMS

The objectives of this study were to assess whether 25 g/d lupin protein, integrated into a mixed diet, might affect cardiovascular risk factors and whether l-arginine was responsible for these effects.

METHODS

Seventy-two hypercholesterolemic subjects participated in the randomized, controlled, double-blind three-phase crossover study. They were assigned to three diets with 25 g/d lupin protein (LP), milk protein (MP) or milk protein plus 1.6 g/d arginine (MPA) each for 28 d in a random order interrupted by 6-week washout periods. Lupin protein and the comparator milk protein were incorporated into complex food products (bread, roll, sausage, and vegetarian spread). Arginine was administered via capsules. Sixty-eight subjects were included in final analyses.

RESULTS

Compared with MP, LDL cholesterol was significantly lower after LP. Compared with MP and MPA, homocysteine was significantly lower after LP. Compared with baseline, concentrations of total, LDL, and HDL cholesterol significantly decreased after LP and MPA. Triacylglycerols and uric acid significantly decreased after LP. The relative changes in total and LDL cholesterol were significantly greater for subjects with severe hypercholesterolemia (>6.6 mmol/L) than those with moderate hypercholesterolemia (5.2-6.6 mmol/L).

CONCLUSIONS

The present study showed for the first time that incorporation of 25 g/d of lupin protein into a variety of complex food products lowers total and LDL cholesterol, triacylglycerols, homocysteine, and uric acid in hypercholesterolemic subjects. The hypocholesterolemic effect is stronger in subjects with severe hypercholesterolemia. Arginine might be responsible for some, but not all of the beneficial effects of lupin protein. This trial was registered at http://clinicaltrials.gov (study ID number NCT01598649).

Isolation and foaming functionality of acid-soluble protein from lupin (Lupinus angustifolius) kernels

BACKGROUND

Australian sweet lupin (ASL) protein is conventionally isolated by alkaline extraction/acid precipitation, leaving a waste stream containing acid-soluble proteins (ASPs) and contaminating raffinose family oligosaccharides (RFOs). The foaming functionality of ASP isolated from ASL is not known, but ASP from another lupin species has demonstrated high foaming functionality.

RESULTS

Pre-soaking ASL kernels increased their protein/RFO ratio; however, some protein was lost by soaking. The foaming capacity of ASL protein isolated by different methods was ranked in the following order: alkaline extraction/isoelectric precipitation < direct acid extraction (novel ASP) < supernatant from isoelectric precipitation (conventional ASP) < ultrafiltered novel ASP = fresh egg white. Electrophoresis indicated enrichment of γ-conglutin and albumin peptides in ASPs and of a single peptide in the fibre residue from alkaline extraction.

CONCLUSION

The high foaming capacity of ultrafiltered novel ASP, similar to that of fresh egg white, indicates the potential of this lupin protein as a food ingredient for foaming applications.

Lupin protein positively affects plasma LDL cholesterol and LDL:HDL cholesterol ratio in hypercholesterolemic adults after four weeks of supplementation: a randomized, controlled crossover study

BACKGROUND

A couple of studies indicate a favorable impact of lupin protein on cardiovascular risk factors in humans. These studies, however, used relatively high doses of > 33 g/d, which can hardly be consumed under physiological conditions. Therefore, we investigated the effect of 25 g/d lupin protein isolate (LPI) on selected cardiovascular markers and on serum amino acids.

METHODS

A total of 33 hypercholesterolemic subjects participated in a randomized, controlled, double-blind crossover study. LPI and the active comparator milk protein isolate (MPI) were incorporated in protein drinks and consumed over 8 wk separated by a 4 wk washout period. Anthropometric data, blood pressure, and nutrient intake were assessed at baseline and after 8 wk of both protein interventions. Blood was sampled at baseline, wk 4 and wk 8. All 33 subjects were included in final statistical analyses using repeated measures ANOVA with the general linear model or using linear mixed model.

RESULTS

Except for higher HDL cholesterol at wk 4 of LPI (P ≤ 0.036), anthropometric parameters, blood pressure, and plasma lipids did not differ among LPI and MPI intervention. Compared to baseline, the primary outcome LDL cholesterol was significantly reduced after 4 wk of both interventions (P ≤ 0.008), while LDL:HDL cholesterol ratio was decreased only by LPI (P = 0.003). These time effects were restricted to subjects with higher hypercholesterolemia and disappeared after 8 wk. Blood pressure was reduced after 8 wk of LPI (P ≤ 0.044). Almost all serum amino acids were higher at wk 4 but not at wk 8 of MPI compared to LPI. Following 4 wk and 8 wk of LPI intervention, most amino acids remained unchanged. Both interventions caused a slight, but significant rise in body weight and body fat after 8 wk (P ≤ 0.045).

CONCLUSION

In conclusion, 25 g LPI can beneficially modulate plasma LDL cholesterol at least over short-term. Using appropriate dietetic conditions that improve consumer compliance and avoid changes in energy intake as well as in body composition, lupin protein could positively impact cardiovascular risk factors particularly in individuals with higher hypercholesterolemia.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01304992.

Hypocholesterolaemic effects of lupin protein and pea protein/fibre combinations in moderately hypercholesterolaemic individuals

The present study was aimed to evaluate the effect of plant proteins (lupin protein or pea protein) and their combinations with soluble fibres (oat fibre or apple pectin) on plasma total and LDL-cholesterol levels. A randomised, double-blind, parallel group design was followed: after a 4-week run-in period, participants were randomised into seven treatment groups, each consisting of twenty-five participants. Each group consumed two bars containing specific protein/fibre combinations: the reference group consumed casein+cellulose; the second and third groups consumed bars containing lupin or pea proteins+cellulose; the fourth and fifth groups consumed bars containing casein and oat fibre or apple pectin; the sixth group and seventh group received bars containing combinations of pea protein and oat fibre or apple pectin, respectively. Bars containing lupin protein+cellulose ( - 116 mg/l, - 4·2%), casein+apple pectin ( - 152 mg/l, - 5·3%), pea protein+oat fibre ( - 135 mg/l, - 4·7%) or pea protein+apple pectin ( - 168 mg/l, - 6·4%) resulted in significant reductions of total cholesterol levels (P<0·05), whereas no cholesterol changes were observed in the subjects consuming the bars containing casein+cellulose, casein+oat fibre or pea protein+cellulose. The present study shows the hypocholesterolaemic activity and potential clinical benefits of consuming lupin protein or combinations of pea protein and a soluble fibre, such as oat fibre or apple pectin.

Cholesterol-lowering effect of dietary Lupinus angustifolius proteins in adult rats through regulation of genes involved in cholesterol homeostasis

In the absence of a clear indication from previous studies, a rat study was designed to evaluate a possible hypolipidaemic effect of Lupinus angustifolius (blue lupin) proteins. Rats were fed for 28days Nath's hypercholesterolaemic diets containing 20% casein or blue lupin proteins. After 14 and 28days of dietary treatment, blue-lupin-fed rats had markedly lower plasma total cholesterol levels than rats fed casein (-53.0% and -55.3%, respectively, p<0.0005). No significant differences were instead observed for triglyceride and HDL-cholesterol levels between the two groups. Lupin-protein-fed rats displayed higher hepatic mRNA levels of SREBP-2, a major transcriptional regulator of intracellular cholesterol levels, and CYP7A1, the rate-limiting enzyme in bile acid biosynthesis (p<0.05). In conclusion, the present study demonstrates a marked cholesterol-lowering activity of proteins from L. angustifolius in rats. Moreover, blue lupin proteins appear to affect cellular lipid homeostasis by up-regulating SREBP-2 and CYP7A1 genes.