Lupine (Lupinus spp.) proteins: characteristics, safety and food applications

Pereira C, Mafra I, Costa J. γ-Conglutin Immunoreactivity Is Differently Affected by Thermal Treatment and Gastrointestinal Digestion in Lupine Species

Lupine is a legume commonly used in human diet as a functional food due to its high nutritional content and important technological properties. However, its consumption can lead to the manifestation of adverse immunological reactions, posing significant health issues in sensitized/allergic patients. This work aims to investigate the effect of food processing combined with simulated gastrointestinal (GI) digestion on the immunoreactivity of lupine γ-conglutin. Model foods of wheat pasta containing 35% of lupine flour (Lupinus albus, L. luteus, and L. angustifolius) were prepared and submitted to a boiling process. The proteins were extracted and their profiles characterized by SDS-PAGE. Simulated GI digestion was performed on thermally treated pasta using the INFOGEST harmonized digestion protocol 2.0. The IgG binding capacity of γ-conglutin was assessed by immunoblotting in non-reducing conditions and indirect ELISA with specific antibodies. Results demonstrate that the boiling treatment affected the immunoreactivity of the three lupine species differently. Simulated GI digestion led to extensive destruction of the protein structure, more significant in the intestinal phase, reducing but not abolishing the IgG affinity to γ-conglutin and its potential presentation to immunocompetent cells. This information can offer valuable insights to the food industry for developing food formulations with reduced allergenic properties.

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.

Effect of roasting temperature and soaking time on the nutritional, antinutrional and sensory properties of protein-based meat analog from lupine

White lupine is a legume crop rich in adequate valuable nutrient profiles especially used as a possible source of proteins where animal-based proteins are scarce. However, there is little documented information about the effect of processing conditions to produce lupine protein-based meat analog. This study explores the impact of roasting temperature (raw, 130, 140, and 150 °C) and soaking time (raw, 2, 4, and 6 days) on the chemical compositions, physical quality, and sensory attributes of meat analog. The result showed that roasting at 140 °C and soaking for 4 days significantly increased (p˂0.05) the proximate and mineral contents of the meat analog. The highest protein content (82.46 %) was obtained at T2t2 (roasted at 140 °C and soaked for 4 days). While the lowest protein content (62.47 %) was observed at T3t3 (roasted at 150 °C and soaked for 4 days). Similarly, the highest (93.17 %) and lowest (79.47 %) cooking yields were obtained at T2t2 and T3t3 respectively. Roasting and soaking conditions also showed a significant effect (p˂0.05) on the anti-nutrient contents of meat analog. The highest overall sensory acceptability (6.40) of the meat analog was observed at T2t2. The research suggests that suitable processing conditions can enhance the nutritional profiles of lupine protein-based meat analog, potentially enabling its industrial production and global market entry.

Effects of molecular structure and charge state on the foaming and emulsifying properties of Spirulina protein isolates

Microalgae protein holds great potential for various applications in the food industry. However, the current knowledge regarding microalgae protein remains limited, with little information available on its functional properties. Furthermore, the relationship between its molecular structure and functional properties is not well defined, which limits its application in food processing. This study aims to addresses these gaps though an analysis of the emulsibility and foamability of various soluble protein isolates from two species of Spirulina (Arthospira platensis and Spirulina platensis), and the functional properties of Spirulina protein isolates in relation to its molecular structure and charge state. Results revealed that the degree of cross-linking and aggregation or folding and curling of protein tertiary structures was higher in the highly soluble Spirulina protein isolates (AP50% and SP50%) than in the low-solubility isolates (AP30% and SP30%). The foaming capacity (FC) of AP50% and SP50% was found to be lower than that of AP30% and SP30%. Spirulina protein isolates can stably adsorb at the air-water interface for at least 20 min and possessed good interfacial activity. A high pH value was found to promote cross-linking of protein particles at the oil-water interface, thereby reinforcing the internal network structure of emulsions and increasing viscosity. These findings provide preliminary insights for potential applications of Spirulina protein isolates in food production, especially towards quality improvement.

Lupin as Ingredient in Durum Wheat Breadmaking: Physicochemical Properties of Flour Blends and Bread Quality

The popularity of adding pulse flours to baked goods is growing rapidly due to their recognised health benefits. In this study, increasing amounts (3, 7, 10, and 15%) of white lupin flour (Lupinus albus L.) and of protein concentrate from narrow-leaved lupin (Lupinus angustifolius L.) were used as replacements for durum wheat semolina to prepare bread, and their effects on the physicochemical properties of the flour blends, as well as the technological and sensory qualities of bread, were evaluated. The addition of protein concentrate from narrow-leaved lupin and white lupin flour increased the water binding capacity and the leavening rate compared to pure semolina. A farinograph test indicated that the dough development time had a slight but significant tendency to increase with the addition of lupin flour and protein concentrate of narrow-leaved lupin, while had a negative effect on the stability of dough. The alveograph strength decreased (225, 108, and 76 × 10-4 J for dough made with semolina, 15% of protein concentrate from narrow-leaved lupin, and 15% of white lupin flour, respectively), whereas there was an upward trend in the P/L ratio. Compared to re-milled semolina, the samples with lupin flour and protein concentrate from narrow-leaved lupin had low amylase activity, with falling number values ranging from 439 s to 566 s. The addition of the two different lupin flours lowered the specific volumes of the breads (2.85, 2.39, and 1.93 cm3/g for bread made from semolina, from 15% of protein concentrate from narrow-leaved lupin, and from 15% of white lupin flour, respectively) and increased their hardness values (up to 21.34 N in the bread with 15% of protein concentrate from narrow-leaved lupin). The porosity of the loaves was diminished with the addition of the two lupin flours (range of 5-8). The sensory analysis showed that the addition of white lupin flour or protein concentrate from narrow-leaved lupin did not impart any unpleasant flavours or odours to the bread. To conclude, the use of lupin in breadmaking requires adjustments to strengthen the gluten network but does not require a deflavouring process.

Influence of Roasting Temperature on the Detectability of Potentially Allergenic Lupin by SDS-PAGE, ELISAs, LC-MS/MS, and Real-Time PCR

Seeds of "sweet lupins" have been playing an increasing role in the food industry. Lupin proteins may be used for producing a variety of foods, including pasta, bread, cookies, dairy products, and coffee substitutes. In a small percentage of the population, lupin consumption may elicit allergic reactions, either due to primary sensitization to lupin or due to cross-allergy with other legumes. Thus, lupin has to be declared on commercial food products according to EU food regulations. In this study, we investigated the influence of roasting seeds of the L. angustifolius cultivar "Boregine" on the detectability of lupin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), ELISAs, LC-MS/MS, and real-time PCR. Seeds were roasted by fluidized bed roasting, and samples were drawn at seed surface temperatures ranging from 98 °C to 242 °C. With increasing roasting temperature, the extractability of proteins and DNA decreased. In addition, roasting resulted in lower detectability of lupin proteins by ELISAs and LC-MS/MS and lower detectability of DNA by real-time PCR. Our results suggest reduced allergenicity of roasted lupin seeds used for the production of "lupin coffee"; however, this has to be confirmed in in vivo studies.

How germination time affects protein hydrolysis of lupins during gastroduodenal digestion and generation of resistant bioactive peptides

Germination time is a critical factor that influences the digestibility and bioactivity of proteins in pulses. The objective was to understand the effect of sprouting time on protein hydrolysis (PH) and the release of bioactive peptides during digestion of lupin (Lupinus angustifolius L.) to provide recommendations on the optimum germination time for maximum nutritional and health benefits. Protein hydrolysis was monitored during germination and digestion by gel electrophoresis, size exclusion chromatography, and the analysis of soluble protein (SP), peptides (PEP), free amino acids (FAA) and free amino groups. The anti-inflammatory activity of intestinal digests was investigated in cell culture assays. Peptidomic and in silico analyses of intestinal digesta were conducted to identify digestion-resistant bioactive fragments. Germination time increased SP, PEP, and FAA. During digestion, the PH and release of small peptides was higher in sprouted lupin than control flour. Intestinal digests from sprouted lupin flour for 7 days exhibited the highest anti-inflammatory activity. In this sample, 11 potential bioactive peptides were identified. These findings open the exploration of novel food formulations based on sprouted lupins with higher protein digestibility and health-promoting potential.

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.

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.

Alternative Protein Sources and Novel Foods: Benefits, Food Applications and Safety Issues

The increasing size of the human population and the shortage of highly valuable proteinaceous ingredients has prompted the international community to scout for new, sustainable, and natural protein resources from invertebrates (e.g., insects) and underutilized legume crops, unexploited terrestrial and aquatic weeds, and fungi. Insect proteins are known for their nutritional value, being rich in proteins with a good balance of essential amino acids and being a valuable source of essential fatty acids and trace elements. Unconventional legume crops were found rich in nutritional, phytochemical, and therapeutic properties, showing excellent abilities to survive extreme environmental conditions. This review evaluates the recent state of underutilized legume crops, aquatic weeds, fungi, and insects intended as alternative protein sources, from ingredient production to their incorporation in food products, including their food formulations and the functional characteristics of alternative plant-based proteins and edible insect proteins as novel foods. Emphasis is also placed on safety issues due to the presence of anti-nutritional factors and allergenic proteins in insects and/or underutilized legumes. The functional and biological activities of protein hydrolysates from different protein sources are reviewed, along with bioactive peptides displaying antihypertensive, antioxidant, antidiabetic, and/or antimicrobial activity. Due to the healthy properties of these foods for the high abundance of bioactive peptides and phytochemicals, more consumers are expected to turn to vegetarianism or veganism in the future, and the increasing demand for such products will be a challenge for the future.

Consumer Perception and Acceptability of Lupin-Derived Products: A Systematic Review

The addition of lupin into other foods can enhance their nutritional value and may be an acceptable approach to introducing lupin into the food supply, particularly as an ingredient. Lupin could be used in many food products (bakery products, pasta, beverages, meat products and dairy products) to improve their protein content and possible nutraceutical effects. The main aim of this study is to summarise the recent formulation trends with lupin as an ingredient of new food products based on consumer perception and acceptability. The present systematic literature review was conducted through the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The eligibility criteria for the articles to be considered were: (a) the manufacturing of a food product with lupin as a formulation ingredient; (b) the food product developed was tested by a sensorial panel. A total of 33 studies filled the inclusion criteria and were incorporated into the qualitative synthesis. The sensory analysis of each product was notoriously different based on the jury evaluators and measurement scales used but revealed high acceptability rates for possible future consumers. The high protein and fibre contents of lupin were the most cited reason associated with the importance of nutrient-rich food products for consumers. More research on foods with high nutrition profiles and well-established sustainability parameters is crucial to promote healthier food environments.

White Lupin Adaptation to Moderately Calcareous Soils: Phenotypic Variation and Genome-Enabled Prediction

White lupin is a promising high-protein crop, the cultivation of which is limited by a lack of adaptation to soils that are even just mildly calcareous. This study aimed to assess the phenotypic variation, the trait architecture based on a GWAS, and the predictive ability of genome-enabled models for grain yield and contributing traits of a genetically-broad population of 140 lines grown in an autumn-sown environment of Greece (Larissa) and a spring-sown environment of the Netherlands (Ens) that featured moderately calcareous and alkaline soils. We found large genotype × environment interaction and modest or nil genetic correlation for line responses across locations for grain yield, a lime susceptibility score, and other traits, with the exception of individual seed weight and plant height. The GWAS identified significant SNP markers associated with various traits that were markedly inconsistent across locations, while providing direct or indirect evidence for widespread polygenic trait control. Genomic selection proved to be a feasible strategy, owing to a moderate predictive ability for yield and lime susceptibility in Larissa (the site featuring greater lime soil stress). Other supporting results for breeding programs where the identification of a candidate gene for lime tolerance and the high reliability of genome-enabled predictions for individual seed weight.

White Lupin Drought Tolerance: Genetic Variation, Trait Genetic Architecture, and Genome-Enabled Prediction

White lupin is a high-protein crop requiring drought tolerance improvement. This study focused on a genetically-broad population of 138 lines to investigate the phenotypic variation and genotype × environment interaction (GEI) for grain yield and other traits across drought-prone and moisture-favourable managed environments, the trait genetic architecture and relevant genomic regions by a GWAS using 9828 mapped SNP markers, and the predictive ability of genomic selection (GS) models. Water treatments across two late cropping months implied max. available soil water content of 60-80% for favourable conditions and from wilting point to 15% for severe drought. Line yield responses across environments featured a genetic correlation of 0.84. Relatively better line yield under drought was associated with an increased harvest index. Two significant QTLs emerged for yield in each condition that differed across conditions. Line yield under stress displayed an inverse linear relationship with the onset of flowering, confirmed genomically by a common major QTL. An adjusted grain yield computed as deviation from phenology-predicted yield acted as an indicator of intrinsic drought tolerance. On the whole, the yield in both conditions and the adjusted yield were polygenic, heritable, and exploitable by GS with a high predictive ability (0.62-0.78). Our results can support selection for climatically different drought-prone regions.

Bioactive Peptides from Lupinus spp. Seed Proteins-State-of-the-Art and Perspectives

Nowadays, the search for food-suitable plant proteins is a great challenge. In addition to their sustainability and nutritional value, the focus is more and more on possible positive interactions with human health. To date, the presence of bioactive peptides encrypted in the structure of protein opens new perspectives, addressing the food industry’s request for new ingredients with technological properties and also the nutraceutical and pharmaceutical sectors based on multifunctional health applications. Lupinus is a sustainable genus of the legume family Fabaceae, and the lupin seed-derived bioactive peptides have demonstrated different effects including anti-inflammatory, antidiabetic, antioxidant, antibacterial, hypocholesterolemic, and antihypertensive activities. This review aims to discuss the current knowledge on lupin protein and their bioactive peptides, highlighting the documented health claims, but also the possibility of allergenicity and the work to be done for the development of new functional products.

Seafood alternatives: assessing the nutritional profile of products sold in the global market

The global market for seafood alternatives is witnessing an exponential growth. Nevertheless, the nutritional quality of such products is scarcely studied. Thus, this study aimed to evaluate, for the first time, the nutritional quality of seafood alternatives launched in the global market from 2002 to 2021 and to compare them with the conventional seafood products. Using the Mintel Global New Products Database, the nutritional information of seafood alternatives (i.e., tuna, shrimps, calamari, fish fingers, fish sticks, salmon, caviar, and fillet) was retrieved, and compared with conventional products. A total of 149 seafood alternatives were identified, of which 83 items had complete mandatory nutritional labeling. Conventional products (n = 973) were also collected, from which 130 products have a complete nutritional labeling. Results revealed that tuna, shrimps, caviar and fillet alternatives contained significantly less protein than conventional products, while calamari, fish fingers, fish sticks and salmon alternatives had similar amounts to their conventional counterparts. Salt content was significantly higher in tuna, fish fingers and sticks substitutes, but lower in shrimps, calamari and caviar alternatives compared to conventional products. Overall, the commercially available seafood alternatives have nutritional strengths and some shortcomings to be further addressed in future research such as low protein content. Additionally, fortification of seafood alternatives with micronutrients, such as omega-3 fatty acids and vitamins (A, B, and D), should be considered to ensure a nutritional equivalence with the conventional products.

Vegan Egg: A Future-Proof Food Ingredient?

Vegan eggs are designed with the aim to provide a healthier and more sustainable alternative to regular eggs. The major drivers of this industry are the increasing prevalence of egg allergies, awareness towards environmental sustainability, and the shift to vegan diets. This study intends to discuss, for the first time, the vegan egg market, including their formulation, nutritional aspects, and some applications (i.e., mayonnaise and bakery products). Recreating the complete functionality of eggs using plant-based ingredients is very challenging due to the complexity of eggs. Current, but scarce, research in this field is focused on making mixtures of plant-based ingredients to fit specific food formulations. Nutritionally, providing vegan eggs with similar or higher nutritional value to that of eggs can be of relevance to attract health-conscious consumers. Claims such as clean labels, natural, vegan, animal-free, gluten-free, and/or cholesterol-free can further boost the position of vegan eggs in the market in the coming year. At present, this market is still in its infancy stages, and clear regulations of labeling, safety, and risk assessment are deemed mandatory to organize the sector, and protect consumers.