Relationship between proportion and composition of albumins, and in vitro protein digestibility of raw and cooked pea seeds (Pisum sativum L.)

Targeted hydrothermally induced cell biopolymer changes explain the in vitro digestion of starch and proteins in common bean (Phaseolus vulgaris) cotyledons

Digestion of macro-nutrients (protein and starch) in pulses is a consequence of the interplay of both extrinsic (process-related) and intrinsic (matrix-dependent) factors which influence their level of encapsulation and physical state, and therefore, their accessibility by the digestive enzymes. The current work aimed at understanding the consequences of hydrothermally induced changes in the physical state of cell biopolymers (cell wall, protein, and starch) in modulating the digestion kinetics of starch and proteins in common beans. The hydrothermal treatments were designed such that targeted microstructural/biopolymer changes occurred. Therefore, bean samples were processed at temperatures between 60 and 95 °C for 90 minutes. It was demonstrated that these treatments allowed the modulation of starch gelatinization, protein denaturation and cell separation. The specific role of hydrothermally induced starch gelatinization and protein denaturation, alongside enhanced cell wall permeability on the digestion kinetics of common bean starch and proteins is illustrated. For instance, bean samples processed at T > 70 °C were marked by higher levels of starch digestibility (Cf values above 47%) compared to the partially (un-)gelatinized samples (processed at T ≤ 70 °C) (Cf values below 35%). Similarly, samples processed at T > 85 °C exhibited significantly higher levels of protein digestibility (Cf values above 47%) resulting from complete protein denaturation. Moreover, increased permeability of the cell wall to digestive enzymes in these samples (T > 85 °C) increased levels of digestibility of both gelatinized starch and denatured proteins. This study provides an understanding of the potential use of hydrothermal processing to obtain pulse-based ingredients with pre-determined microstructural and nutritional characteristics.

Exploring protein structural adaptations and polyphenol interactions: Influences on digestibility in pigeon pea dal and whole grains under heat and germination conditions

Pigeon pea, a protein-rich legume with low protein digestibility (PD) due to its high polyphenol content and other antinutritional factors (ANFs). Consequently, processing methods are crucial to improve PD. We investigated the effects of thermal treatments (cooking, hydrothermal, autoclaving, infrared rays) treatments and germination on modulation of PD, its properties and association with ANFs in two distinct genotypes based on polyphenol content: high (Pusa Arhar 2018-4) and low (ICP-1452). Treatments improved in vitro PD and essential amino acid content, with autoclaving showing significantly higher PD (ICP-1452: 90.4%, Pusa-Arhar 2018-4: 84.32%) ascribed to disruption of tight protein matrices. Significant increase in β-turn, reduction in protein: starch, protein: polyphenol interactions as well as breakdown of storage proteins revealed by the analysis of protein structural properties. This study suggests thermal treatments, particularly autoclaving, can enhance pigeon pea protein's nutritional quality for its utilization as a new ingredient in development of healthy foods.

Solubility, (micro)structure, and in vitro digestion of pea protein dispersions as affected by high pressure homogenization and environmental conditions

In this work, dispersions were prepared with commercial pea protein isolate (PPI) and subjected to different (i) high pressure homogenization (HPH) intensities (0 - 200 MPa) (room temperature, pH 7) or (ii) environmental conditions (60 °C, pH 7 or pH 12) to generate dispersions with distinct protein molecular and microstructural characteristics, impacting protein solubility. Besides, protein digestion was analyzed following the static INFOGEST in vitro digestion protocol. Generally, increasing pressure of the homogenization treatment was linked with decreasing particle sizes and enhanced protein digestion. More specifically, the dispersion that did not undergo HPH (0 MPa) as well as the dispersion treated at 60 °C, pH 7, had highly similar microstructures, consisting of large irregular particles (10 - 500 µm) with shell-like structures, and exhibited low solubility (around 15 % and 28 %, respectively), which resulted in limited proteolysis (35 % and 42 %, respectively). In contrast, the dispersion subjected to HPH at 100 MPa and the dispersion treated at 60 °C, pH 12 also had similar microstructures with small and homogeneous particles (<1 µm), and exhibited relatively good solubility (54 % and 31 %, respectively), which led to enhanced protein digestion levels (87 % and 74 %, respectively). This study highlights the potential of food processing on macronutrient (micro)structure and further gastrointestinal stability and functionality.

Are oilseeds a new alternative protein source for human nutrition?

This review focuses on the potential use, nutritional value and beneficial health effects of oilseeds as a source of food protein. The process of extracting oil from oilseeds produces a by-product that is rich in proteins and other valuable nutritional and bioactive components. This product is primarily used for animal feed. However, as the demand for proteins continues to rise, plant-based proteins have a real success in food applications. Among the different plant protein sources, oilseeds could be used as an alternative protein source for human diet. The data we have so far show that oilseeds present a protein content of up to 40% and a relatively well-balanced profile of amino acids with sulphur-containing amino acids. Nevertheless, they tend to be deficient in lysine and rich in anti-nutritional factors (ANFs), which therefore means they have lower anabolic potential than animal proteins. To enhance their nutritional value, oilseed proteins can be combined with other protein sources and subjected to processes such as dehulling, heating, soaking, germination or fermentation to reduce their ANFs and improve protein digestibility. Furthermore, due to their bioactive peptides, oilseeds can also bring health benefits, particularly in the prevention and treatment of diabetes, obesity and cardiovascular diseases. However, additional nutritional data are needed before oilseeds can be endorsed as a protein source for humans.

In vitro digestibility of proteins from red seaweeds: Impact of cell wall structure and processing methods

This study aimed to assess the nutritional quality and digestibility of proteins in two red seaweed species, Gelidium corneum and Gracilaropsis longissima, through the application of in vitro gastrointestinal digestions, and evaluate the impact of two consecutive processing steps, extrusion and compression moulding, to produce food snacks. The protein content in both seaweeds was approximately 16 %, being primarily located within the cell walls. Both species exhibited similar amino acid profiles, with aspartic and glutamic acid being most abundant. However, processing impacted their amino acid profiles, leading to a significant decrease in labile amino acids like lysine. Nevertheless, essential amino acids constituted 35-36 % of the total in the native seaweeds and their processed products. Although the protein digestibility in both seaweed species was relatively low (<60 %), processing, particularly extrusion, enhanced it by approximately 10 %. Interestingly, the effect of the different processing steps on the digestibility varied between the two species. This difference was mainly attributed to compositional and structural differences. G. corneum exhibited increased digestibility with each processing step, while G. longissima reached maximum digestibility after extrusion. Notably, changes in the amino acid profiles of the processed products affected adversely the protein nutritional quality, with lysine becoming the limiting amino acid. These findings provide the basis for developing strategies to enhance protein quality in these seaweed species, thereby facilitating high-quality food production with potential applications in the food industry.

Towards Sustainable Protein Sources: The Thermal and Rheological Properties of Alternative Proteins

Reducing meat consumption reduces carbon emissions and other environmental harms. Unfortunately, commercial plant-based meat substitutes have not seen widespread adoption. In order to enable more flexible processing methods, this paper analyzes the characteristics of commercially available spirulina, soy, pea, and brown rice protein isolates to provide data for nonmeat protein processing that can lead to cost reductions. The thermal and rheological properties, as well as viscosity, density, and particle size distribution, were analyzed for further study into alternative protein-based food processing. The differential scanning calorimetry analysis produced dry amorphous-shaped curves and paste curves with a more distinct endothermic peak. The extracted linear temperature ranges for processing within food production were 70-90 °C for spirulina, 87-116 °C for soy protein, 67-77 °C for pea protein, and 87-97 °C for brown rice protein. The viscosity analysis determined that each protein material was shear-thinning and that viscosity increased with decreased water concentration, with rice being an exception to the latter trend. The obtained viscosity range for spirulina was 15,100-78,000 cP, 3200-80,000 cP for soy protein, 1400-32,700 cP for pea protein, and 600-3500 cP for brown rice protein. The results indicate that extrusion is a viable method for the further processing of protein isolates, as this technique has a large temperature operating range and variable screw speed. The data provided here can be used to make single or multi-component protein substitutes.

Impact of ultrasonication on the contents, profiles and biofunctional properties of free and bound phenolics from white desert truffle (Tirmania nivea) and its protein fractions

The molecular and biofunctional properties of protein and phenolic fractions in edible truffles remain largely unknown. This study examined the effect of ultrasonication on the contents, profiles, and bioactive properties of free and bound phenolics (FP and BP) from desert truffle (Tirmania nivea) and its protein fractions. Protein fractions from the Osborne extraction scheme were biochemically and structurally characterized. The albumin fraction showed the highest abundance (16.8%) and yield (35.8%). Total phenolic contents were the highest in non-sonicated samples (3.5-34.1 mg/g), particularly in the albumin fraction and in whole truffle. FP extracted at 30 °C (FP-30 °C) accounted for the largest proportion of total phenolics in all protein fractions, whereas BP-30 °C and FP-60 °C were predominant in non-sonicated and sonicated truffle, respectively. The highest antioxidant activity was obtained with FP-30 °C extracts from non-sonicated albumins, globulins and truffle (91.9, 72.7 and 30.0%), followed by BP-30 °C from non-sonicated albumins (25.4%) and FP-60 °C from sonicated glutelins-1 (24.2%). High inhibition of α-amylase was evidenced in several extracts, including FP-30 °C from non-sonicated glutelins-1 (99.2%) and FP-30 °C from sonicated globulins (72.4%). Several extracts also displayed high inhibition of angiotensin I-converting enzyme (ACE), including FP-60 °C from non-sonicated glutelins-1 (65.1%) and sonicated glutelins-1 (71.1%) and globulins (64.7%). Most extracts were rich in epicatechin, gallic acid, chlorogenic acid and catechin. Correlations between phenolic content, antioxidant activity, anti-α-amylase and anti-ACE activities were influenced by sonication. Sonication reduced the particle size of the proteins and modified their structural characteristics. These findings demonstrate that white desert truffle proteins co-occur with bioactive phenolics whose functionalities can be tailored by protein fractionation and sonication.

Protein composition and nutritional aspects of pea protein fractions obtained by a modified isoelectric precipitation method using fermentation

Pea albumins are promising for their nutritional, biological, and techno-functional properties. However, this fraction is usually discarded in the industry due to its low protein content compared to globulin fraction and the presence of some anti-nutritional compounds. In the present study, we used an alternative method of pea protein extraction based on alkaline solubilization/isoelectric precipitation in which the reduction of pH was achieved by lactic acid fermentation using specific starters instead of mineral acids. Hence, the main objective of this study was to examine the protein profile and the content of anti-nutritional and nutritional active compounds in pea albumin-rich fractions obtained by the isoelectric extraction method without (control) or with fermentation with different lactic acid bacteria (Streptococcus thermophilus, Lactiplantibacillus plantarum, and their co-culture). Different pea cultivars (Cartouche, Ascension, and Assas) were used here for their differences in protein profile. The results revealed a higher total nitrogen content in albumin-rich fraction for fermented samples and, in particular, for co-culture. The majority of total nitrogen was determined as non-protein (~50%), suggesting the degradation of proteins by LAB to small peptides and amino acids, which were solubilized in the soluble fraction (albumin) as confirmed by size exclusion chromatography (SEC-HPLC) analysis. Moreover, the higher antioxidant activity of fermented albumin samples was attributed to the production of small peptides during extraction. Lactic acid fermentation also resulted in a significant reduction of trypsin inhibitor activity, α-galactoside, and phytic acid content of this fraction compared to control.

Yellow Field Pea Protein (Pisum sativum L.): Extraction Technologies, Functionalities, and Applications

Yellow field peas (Pisum sativum L.) hold significant value for producers, researchers, and ingredient manufacturers due to their wealthy composition of protein, starch, and micronutrients. The protein quality in peas is influenced by both intrinsic factors like amino acid composition and spatial conformations and extrinsic factors including growth and processing conditions. The existing literature substantiates that the structural modulation and optimization of functional, organoleptic, and nutritional attributes of pea proteins can be obtained through a combination of chemical, physical, and enzymatic approaches, resulting in superior protein ingredients. This review underscores recent methodologies in pea protein extraction aimed at enhancing yield and functionality for diverse food systems and also delineates existing research gaps related to mitigating off-flavor issues in pea proteins. A comprehensive examination of conventional dry and wet methods is provided, in conjunction with environmentally friendly approaches like ultrafiltration and enzyme-assisted techniques. Additionally, the innovative application of hydrodynamic cavitation technology in protein extraction is explored, focusing on its prospective role in flavor amelioration. This overview offers a nuanced understanding of the advancements in pea protein extraction methods, catering to the interests of varied stakeholders in the field.

Plant-based meat analogs and fat substitutes, structuring technology and protein digestion: A review

There is currently an increasing trend in the consumption of meat analogs and fat substitutes due to the health hazards by excessive consumption of meat. Simulating the texture and mouthfeel of meat through structured plant-derived polymers has become a popular processing method. In this review, the mechanical structuring technology of plant polymers for completely replacing real meat is mainly introduced in this review, which mainly focuses on the parameters and principles of mechanical equipment for the production of vegan meat. The difference in composition between plant meat and real meat is mainly reflected in the protein, and particular attention should be paid to the digestive characteristics of plant meat protein in the gastrointestinal tract. Therefore, the differences in the protein digestibility properties of meat analogs and real meat is discussed in this review, focusing primarily on protein digestibility and peptide/amino acid composition of mechanically structured vegan meats. In terms of fat substitutes for meat products, the types of plant polymer colloidal systems used for meat fat substitutes is comprehensively introduced, including emulsion, hydrogel and oleogel.

Combination of three null mutations affecting seed protein accumulation in pea (Pisum sativum L.) impacts positively on digestibility

The presence of so-called anti-nutritional factors can reduce the bioavailability of nutrients following consumption of seeds which are otherwise an excellent source of proteins, carbohydrates and micronutrients. Among the proteins associated with negative effects on quality in pea (Pisum sativum L.) seeds are lectin, pea albumin 2 (PA2) and trypsin inhibitors (TI). Here we have investigated the impact of these proteins on protein digestibility and amino acid availability, using naturally occurring and derived mutant lines of pea lacking these proteins. The mutations were stacked to generate a triple mutant which was compared with a wild-type progenitor and a line lacking the major seed trypsin inhibitors alone. In vitro digestions following the INFOGEST protocol revealed significant differences in the degree of hydrolysis, protein profile and apparent amino acid availability among the pea variants. Proteins resistant to digestion were identified by MALDI-TOF mass spectrometry and amino acid profiles of digested samples determined. The results indicate that pea seeds lacking certain proteins can be used in the development of novel foods which have improved protein digestibility, and without negative impact on seed protein concentration or yield.

Protein composition of pulses and their protein isolates from different sources and in different isolation pH values using a reverse phase high performance liquid chromatography method

The objective of this study was to compare the composition of pulse proteins isolated from lentils and green and yellow peas at two isolation pH values (9 and 11) and determine the effect of this variability on protein functionality. Chromatogram peaks obtained from reverse-phase high performance liquid chromatography were identified by isolation of albumin-, vicilin- and legumin-rich fractions for the three pulses. Protein composition was obtained for each isolate and compared against that of the originating pulse flour. Lentil flour showed the highest level of vicilin with a vicilin/legumin ratio of ∼ 2.5, while this ratio was 1.3 and 1.2 for green and yellow pea flour, respectively. Albumin content of yellow pea flour was high (∼36.1 %), which reduced to ∼ 15-19 % in isolated proteins showing a loss in albumins during the isolation. Higher extraction pH increased pea protein yield but led to lower protein solubility with no changes in foaming properties and in-vitro digestibility.

How heavy metal stress affects the growth and development of pulse crops: insights into germination and physiological processes

The current work is an extensive review addressing the effects of heavy metals in major pulse crops such as Chickpea (Cicer arietinum L.), Pea (Pisum sativum L.), Pigeonpea (Cajanus cajan L.), Mung bean (Vigna radiata L.), Black gram (Vigna mungo L.) and Lentil (Lens culinaris Medik.). Pulses are important contributors to the global food supply in the world, due to their vast beneficial properties in providing protein, nutritional value and health benefits to the human population. Several studies have reported that heavy metals are injurious to plants causing inhibition in plant germination, a decrease in the root and shoot length, reduction in respiration rate and photosynthesis. Properly disposing of heavy metal wastes has become an increasingly difficult task to solve in developed countries. Heavy metals pose one of the substantial constraints to pulse crops growth and productivity even at low concentrations. This article attempts to present the morphological, biochemical and various physiological changes induced on the pulse crops grown under various heavy metal stress such as As, Cd, Cr, Cu, Pb, and Ni.

Analysis and correlations of the protein content and selected 'antinutrients' of faba beans (Vicia faba) in a German sample set of the cultivation years 2016, 2017, and 2018

BACKGROUND

Faba beans (Vicia faba) experienced a significant revival in cultivation in Western Europe in the last decade. In this study, potential correlations between protein content (PC), trypsin inhibitory activity (TIA), and tannin content were investigated in a large German sample set with bean samples obtained from 50 different farms present in 11 German federal states. Three consecutive cultivation years (2016, 2017, and 2018) were included.

RESULTS

The faba bean samples were grown under real cultivation conditions without any specific experimental design and finally marketed by the farmers. This enabled researchers to identify the relationship and extent of the three quality parameters towards the varying cultivation conditions and practices. Moreover, the correlations observed between the parameters were brought into the context of well-known theoretical plant hypotheses such as the carbon-nutrient balance hypothesis (CNBH), the growth-differentiation balance hypothesis (GDBH), as well as the protein competition model (PCM) for evaluating the potential for use in predictions. The study showed a significant negative correlation between PC and tannin content in faba beans over each cultivation year, whereas a positive correlation between TIA and tannin content was found. No clear correlation was observed between PC and TIA.

CONCLUSION

The three plant hypotheses (CNBH, GDBH, and PCM) seem to be not fully valid. Nonetheless, these findings might be a useful guideline for predicting the composition of selected compounds, and sustainable recommendations about cultivation and exploitation for the feed and food sector can be derived. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The internalization mechanisms and trafficking of the pea albumin in Caco-2 cells

Pea albumin (PA) can reach the intestine in the active form because it is highly resistant to gastric acid and proteolytic enzymes after their oral intake, which can supply various bioactivities. However, there is no detailed knowledge of the intestinal cell uptake about PA. The aim of this work was to study the internalization mechanism and intracellular trafficking route of PA. The uptake of PA-cyanine 5.5 NHS ester (Cy5.5) was a time-dependent and concentration-dependent process in Caco-2 cells. Endocytosis inhibitors or small interfering RNA (siRNA) techniques revealed that the internalization of PA-Cy5.5 was energy-dependent and mediated by caveolin-mediated endocytosis. Furthermore, we observed colocalization of PA-Cy5.5 and its subcellular localization in Caco-2 cells by using confocal laser scanning microscopy, which revealed that the intracellular trafficking process of PA-Cy5.5 was related to endoplasmic reticulum, Golgi, and lysosome. Interestingly, PA can alleviate lipopolysaccharide -induced ER stress, which may be the main reason why pea albumin is anti-inflammatory. Overall, our findings suggest caveolin may be critical for PA uptake in enterocytes and could contribute to explore the bioactivities mechanism of pea albumin in body.

Pea Albumin Attenuates Dextran Sulfate Sodium-Induced Colitis by Regulating NF-κB Signaling and the Intestinal Microbiota in Mice

BACKGROUND

Inflammatory bowel disease remains a global burden with rapidly increasing incidence and prevalence in both industrialized countries and developing countries. In this study, we prepared pea albumin from pea seeds and determined its beneficial effects being anti-inflammatory and on gut microbiota modulation in dextran sulfate sodium (DSS)-challenged mice.

METHOD

Six-week-old C57BL/6N male mice received an equivalent volume (200 μL) of sterile phosphate balanced solution, 0.375, 0.75, or 1.50 g/kg body weight (BW) of pea albumin that was subjected to 2.0% DSS for 7 days to induce colitis. On day 17 of the experiment, all mice were sacrificed after blood sample collection, and colon tissue and colon contents were collected. BW change curve, colon length, myeloperoxidase (MPO) activity, mucus staining, immunofluorescence staining of T cells and macrophages, cytokines, pro-inflammatory genes expression, nuclear factor-κB (NF-κB) and signal transducer, and activator of transcription 3 (STAT3) signaling pathways as well as 16S DNA sequence were measured.

RESULTS

Our results show that pea albumin alleviates DSS-induced BW loss, colon length shortening, enhanced MPO activity, cytokines secretion, mucus deficiency, and inflammatory cell infiltration, as well as enhanced pro-inflammatory genes expression. In addition, the overactivation of NF-κB and STAT3 following DSS exposure is attenuated by pea albumin administration. Of particular interest, pea albumin oral administration restored gut microbiota dysbiosis as evidenced by enhanced α-diversity, restored β-diversity, and promoted relative abundance of Lactobacillus and Lachnospiraceae_NK4A136_group.

CONCLUSION

Taken together, the data provided herein demonstrated that pea albumin plays a protective role in DSS-induced colitis by reducing inflammatory cell infiltration, pro-inflammatory genes expression and pro-inflammatory cytokines release, inactivation of NF-κB signal, and gut microbiota modulation.

Legume Seed Protein Digestibility as Influenced by Traditional and Emerging Physical Processing Technologies

The increased consumption of legume seeds as a strategy for enhancing food security, reducing malnutrition, and improving health outcomes on a global scale remains an ongoing subject of profound research interest. Legume seed proteins are rich in their dietary protein contents. However, coexisting with these proteins in the seed matrix are other components that inhibit protein digestibility. Thus, improving access to legume proteins often depends on the neutralisation of these inhibitors, which are collectively described as antinutrients or antinutritional factors. The determination of protein quality, which typically involves evaluating protein digestibility and essential amino acid content, is assessed using various methods, such as in vitro simulated gastrointestinal digestibility, protein digestibility-corrected amino acid score (IV-PDCAAS), and digestible indispensable amino acid score (DIAAS). Since most edible legumes are mainly available in their processed forms, an interrogation of these processing methods, which could be traditional (e.g., cooking, milling, extrusion, germination, and fermentation) or based on emerging technologies (e.g., high-pressure processing (HPP), ultrasound, irradiation, pulsed electric field (PEF), and microwave), is not only critical but also necessary given the capacity of processing methods to influence protein digestibility. Therefore, this timely and important review discusses how each of these processing methods affects legume seed digestibility, examines the potential for improvements, highlights the challenges posed by antinutritional factors, and suggests areas of focus for future research.

Enzymatic Hydrolysis of Pulse Proteins as a Tool to Improve Techno-Functional Properties

Pulse proteins are being increasingly investigated as nutritious and functional ingredients which could provide alternatives to animal proteins; however, pulse protein ingredients do not always meet the functionality requirements necessary for various applications. Consequently, enzymatic hydrolysis can be employed as a means of improving functional properties such as solubility, emulsifying, foaming, and gelling properties. This review aims to examine the current literature regarding modification of these properties with enzymatic hydrolysis. The effects of enzymatic hydrolysis on the functionality of pulse proteins generally varies considerably based on the enzyme, substrate, processing steps such as heat treatment, degree of hydrolysis, and pH. Differences in protease specificity as well as protein structure allow for a wide variety of peptide mixtures to be generated, with varying hydrophobic and electrostatic properties. Typically, the most significant improvements are seen when the original protein ingredient has poor initial functionality. Solubility is usually improved in the mildly acidic range, which may also correspond with improved foaming and emulsifying properties. More work should be carried out on the potential of enzymatic hydrolysis to modify gelation properties of pulse proteins, as the literature is currently lacking. Overall, careful selection of proteases and control of hydrolysis will be necessary to maximize the potential of enzymatic hydrolysis as a tool to improve pulse protein functionality and broaden the range of potential applications.

Effect of heat treatment on the digestion behavior of pea and rice protein dispersions and their blends, studied using the semi-dynamic INFOGEST digestion method

In the present study, the structuring and breakdown of a 5% protein dispersion prepared with commercial fractions of pea and rice isolates (PPI and RPI, respectively) were monitored by in vitro digestion. These proteins were blended in a 2 : 1 ratio of pea and rice, respectively, as this would deliver a high amino acid score. The effect of heating at 90 °C for 15 min on the digestion behavior was evaluated not only for the blend, but also for the respective protein isolate fractions, using the INFOGEST international consensus, semi-dynamic in vitro gastric model. Digesta were characterized by gel electrophoresis, light scattering, confocal laser scanning microscopy and size exclusion HPLC. Heating increased the solubility of PPI from 15.7% to 26.6% at pH 7.4. RPI showed low solubility (a maximum of 2.6% at pH 2), regardless of the treatment. Confocal microscopy observations evidenced major differences in the aggregates formed during digestion, with larger aggregates for heated PPI. While the unheated pea protein dispersions precipitated near the isoelectric pH, the heated counterpart formed macro-aggregates under the same conditions. In the case of RPI, there were no differences in structuring behaviour between unheated and heat treated reconstituted powder, due to their low solubility. Rice prolamins showed resistance to hydrolysis by pepsin and pancreatic enzymes. In the heated blend, macro-aggregates formed, but with a smaller size compared to heated pea protein alone, suggesting that pea protein aggregation was hindered by the presence of rice proteins. These results demonstrate how the composition of protein isolates can affect their in vitro digestion. However, pre-treatment of plant protein blends, such as heating, can modulate the rate and mechanism of digestion.

Legumes as Functional Food for Cardiovascular Disease

Legumes are an essential food source worldwide. Their high-quality proteins, complex carbohydrates, dietary fiber, and relatively low-fat content make these an important functional food. Known to possess a multitude of health benefits, legume consumption is associated with the prevention and treatment of cardiovascular diseases (CVD). Legume crude protein isolates and purified peptides possess many cardiopreventive properties. Here, we review selected economically valued legumes, their taxonomy and distribution, biochemical composition, and their protein components and the mechanism(s) of action associated with cardiovascular health. Most of the legume protein studies had shown upregulation of low-density lipoprotein (LDL) receptor leading to increased binding and uptake, in effect significantly reducing total lipid levels in the blood serum and liver. This is followed by decreased biosynthesis of cholesterol and fatty acids. To understand the relationship of identified genes from legume studies, we performed gene network analysis, pathway, and gene ontology (GO) enrichment. Results showed that the genes were functionally interrelated while enrichment and pathway analysis revealed involvement in lipid transport, fatty acid and triglyceride metabolic processes, and regulatory processes. This review is the first attempt to collate all known mechanisms of action of legume proteins associated with cardiovascular health. This also provides a snapshot of possible targets leading to systems-level approaches to further investigate the cardiometabolic potentials of legumes.

Impact of Extrusion Temperature on In Vitro Digestibility and Pasting Properties of Pea Flour

Pea flour was extruded at 50, 70, and 90 °C. The in vitro digestibility and characteristics of native and extruded pea flour were investigated. The in vitro starch digestibility (IVSD) and in vitro protein digestibility (IVPD) of the extruded pea flour were higher than those of the native pea flour and increased with increasing extrusion temperature from 50 to 90 °C. The rapidly digestible starch increased to 28.34% at 90 °C, the highest slowly digestible starch (SDS) content was 22.70% at 50 °C, and resistant starch content decreased to 4.71% at 90 °C. The IVPD increased from 80.94% relative to the native pea flour to 90.21% at 90 °C. Improved swelling power enabled the extruded pea flour to exhibit better performance and higher breakdown viscosity and lower setback viscosity than the native pea flour demonstrated that extrusion reduced the thermal stability and retrogradation tendency. Increasing extrusion temperatures greatly reduced the relative crystallinity (based on X-ray diffraction analysis) from 32.69% relative to the native pea flour to 9.76% at 90 °C. Extrusion treatment also reduced β-sheet content (based on Fourier transform infrared spectroscopy analysis) from 36.40% relative to the native pea flour to 31.79% at 90 °C. IVPD and IVSD improved, and the SDS content increased at 50 °C and 70 °C, thereby indicating that extruded pea flour can be applied to healthy food products.

Physicochemical, functional and structural characteristics of grains, flour and protein isolates of Indian quinoa lines

The physicochemical and functional properties of grains, flour and protein isolates (QPI) from different quinoa lines were evaluated. Quinoa flour and protein isolates were characterised by high protein (14.1-15.4% and 78.7-86%, respectively) and phenolic content (419 to 655 mg GAE/100 g). Water and oil absorption capacity of QPI (2.0-3.6 g/g and 2.71-3.32 g/g, respectively) was significantly higher than quinoa flour (1.22 and 2.17 gand 0.9 and1.54 g, respectively). QPI showed desirable functional properties in terms of high foaming capacity (50.8 to 60.2%), foam stability (38.5 to 50.4%), protein solubility (30 and 53.3%), and emulsification index (EAI- 19.2-26.1 m²/g and ESI- 96.7-149.8 min, respectively). Digestibility of QPI ranged between 70.8 and 77.8% and was negatively correlated to random coils. Quinoa lines with higher grain density (GD) showed higher total phenol content (TPC) and WAC and lower FRSA and OAC. QPI with higher proportions of β-structure and random coils had enhanced protein surface activities leading to improved emulsification and foaming capabilities. Among the highly conserved polypeptides (PPs), variations were observed in accumulation of 53, 59 and 32 kDa PPs for grains and 33 and 21-24 kDa PPs for QPI.

Use of Legumes in Extrusion Cooking: A Review

The traditional perception that legumes would not be suitable for extrusion cooking is now completely outdated. In recent years, an increasing number of studies have been conducted to assess the behavior of various types of legume flours in extrusion cooking, proving that legumes have excellent potential for the production of extruded ready-to-eat foods by partially or totally replacing cereals. This review identifies the optimal processing conditions for legume-based and legume-added extruded foods, which allow the improvement of the expansion ratio and give the extrudates the spongy and crisp structure expected by consumers. In particular, the effect of the individual processing parameters on the physical-chemical and nutritional properties of the final product is highlighted. The extrusion cooking process, indeed, has a positive effect on nutritional characteristics, because it induces important modifications on starch and proteins, enhancing their digestibility, and reduces the content of trypsin inhibitors, lectins, phytic acid, and tannins, typically present in legumes. Therefore, the extrusion of legume flours is a viable strategy to improve their nutritional features while reducing home preparation time, so as to increase the consumption of these sustainable crops.

Food processing for the improvement of plant proteins digestibility

Proteins are essential macronutrients for the human diet. They are the primary source of nitrogen and are fundamental for body structure and functions. The plant protein quality (PPQ) refers to the bioavailability, digestibility, and amino acid composition. The digestibility specifies the protein quantity absorbed by an organism relative to the consumed amount and depends on the protein structure, previous processing, and the presence of compounds limiting the digestion. The latter are so-called antinutritional factors (ANF), exemplified by phytates, tannins, trypsin inhibitors, and lectins. Animal proteins are known to have better digestibility than plant proteins due to the presence of ANF in plants. Thus, the inactivation of ANF throughout food processing may increase the PPQ. New food processing, aiming to increase the digestibility of plant proteins, and new sources of proteins are being studied for the animal protein substitution. Here, it is presented the impact of processing on the protein digestibility and reduction of ANF. Several techniques, such as cooking, autoclaving, germination, microwave, irradiation, spray- and freeze-drying, fermentation, and extrusion enhanced the PPQ. The emerging non-thermal technologies impact on protein functionalities but require studies on the protein digestibility. How to accurately determine and how to improve the protein digestibility of a plant source remains a scientific and technological challenge that may be addressed by novel or combining existing processing techniques, as well as by exploring protein-enriched by-products of the food industry.

The Effect of Processing on Digestion of Legume Proteins

The domestic processing methods, soaking, cooking (traditional, microwave, pressure), and baking and the industrial processing, autoclaving, baking, and extrusion are used to improve consumption of legumes. The growing awareness of both health and sustainability turns the focus on protein (bio)availability. This paper reports the effect of these processing methods on the legume protein digestibility. Overall, the protein digestibility increases after processing by the different methods. However, since both the type of legume and the applied methods differ it cannot be concluded which specific method is best for the individual legume type.

Cowpea: an overview on its nutritional facts and health benefits

Cowpea (Vigna unguiculata) is a legume consumed as a high-quality plant protein source in many parts of the world. High protein and carbohydrate contents with a relatively low fat content and a complementary amino acid pattern to that of cereal grains make cowpea an important nutritional food in the human diet. Cowpea has gained more attention recently from consumers and researchers worldwide as a result of its exerted health beneficial properties, including anti-diabetic, anti-cancer, anti-hyperlipidemic, anti-inflammatory and anti-hypertensive properties. Among the mechanisms that have been proposed in the prevention of chronic diseases, the most proven are attributed to the presence of compounds such as soluble and insoluble dietary fiber, phytochemicals, and proteins and peptides in cowpea. However, studies on the anti-cancer and anti-inflammatory properties of cowpea have produced conflicting results. Some studies support a protective effect of cowpea on the progression of cancer and inflammation, whereas others did not reveal any. Because there are only a few studies addressing health-related effects of cowpea consumption, further studies in this area are suggested. In addition, despite the reported favorable effects of cowpea on diabetes, hyperlipidemia and hypertension, a long-term epidemiological study investigating the association between cowpea consumption and diabetes, cardiovascular disease and cancer is also recommended. © 2018 Society of Chemical Industry.

The Effects of Fortification of Legumes and Extrusion on the Protein Digestibility of Wheat Based Snack

Cereal food products are an important part of the human diet with wheat being the most commonly consumed cereal in many parts of the world. Extruded snack products are increasing in consumer interest due to their texture and ease of use. However, wheat based foods are rich in starch and are associated with high glycaemic impact products. Although legume materials are generally rich in fibre and protein and may be of high nutritive value, there is a paucity of research regarding their use in extruded snack food products. The aim of this study was to prepare wheat-based extrudates using four different legume flours: lentil, chickpea, green pea, and yellow pea flour. The effects of adding legumes to wheat-based snacks at different levels (0%, 5%, 10%, and 15%) during extrusion were investigated in terms of protein digestibility. It was observed that fortification of snacks with legumes caused a slight increase in the protein content by 1%–1.5% w/w, and the extrusion technique increased the protein digestibility by 37%–62% w/v. The product developed by extrusion was found to be low in fat and moisture content.

Impact of Radio Frequency, Microwaving, and High Hydrostatic Pressure at Elevated Temperature on the Nutritional and Antinutritional Components in Black Soybeans

In this study, the effects of high hydrostatic pressure (HHP) at elevated temperature (60 °C) and 2 dielectric heating (DH) methods (radio frequency [RF], and microwaving [MW]) on the nutritional compositions and removal of antinutritional factors in black soybeans were studied. Each treatment caused <2% reduction in protein, and 3.3% to 7.0% decline in total amino acid content. However, the proportion of essential amino acid slightly increased in DH treated samples. The treatment decreased fat content (14.0% to 35.7%), but had small influence on fatty acid proportion. Antinutritional factors including trypsin inhibitor, tannins, saponins, and phytic acid were all declined by the 3 treatments, and DH treatment was generally more efficient. The most abundant saponins was decreased >22% in DH treated samples. MW and HHP led to higher in vitro protein digestibility, RF and MW promoted protein aggregation from atomic force microscope topography, but HHP caused more damages on protein subunits as seen from SDS-PAGE image.

Effect of processing methods on compositional evaluation of underutilized legume, Parkia roxburghii G. Don (yongchak) seeds

The present study has been undertaken to analyze the effect of various processing methods like (i) soaking followed by autoclaving with (a) ash, (b) sodium bicarbonate, (c) sugar and (d) water; (ii) dry heating and (iii) fermentation on nutritional and antinutritional components of under-utilized tree legume Parkia roxburghii. The applied methods were found to enhance the protein (15-36 %) and lipid content (11-69 %) and to decrease the other proximal components. All the methods significantly reduced the antinutrients viz. condensed tannins, phytate, saponins, trypsin inhibitors, chymotrypsin inhibitors and lectins. Exceptionally, increased content was documented on total phenolics (117-207 %) and tannins (171-257 %). These reduced antinutritional loads have led to an increase in protein (9-20 %) and starch digestibility (75-254 %). Fermented kernels, the best processed form showed characteristic leguminous pattern for content and composition of amino acids, fatty acids and minerals. So knowledge gathering and exploration of nutritionally balanced under-utilized legumes would enhance food and nutritional security.

Understanding the role of H(2)O(2) during pea seed germination: a combined proteomic and hormone profiling approach

In a previous publication, we showed that the treatment of pea seeds in the presence of hydrogen peroxide (H(2)O(2)) increased germination performance as well as seedling growth. To gain insight into the mechanisms responsible for this behaviour, we have analysed the effect of treating mature pea seeds in the presence of 20 mm H(2)O(2) on several oxidative features such as protein carbonylation, endogenous H(2)O(2) and lipid peroxidation levels. We report that H(2)O(2) treatment of the pea seeds increased their endogenous H(2)O(2) content and caused carbonylation of storage proteins and of several metabolic enzymes. Under the same conditions, we also monitored the expression of two MAPK genes known to be activated by H(2)O(2) in adult pea plants. The expression of one of them, PsMAPK2, largely increased upon pea seed imbibition in H(2)O(2) , whereas no change could be observed in expression of the other, PsMAPK3. The levels of several phytohormones such as 1-aminocyclopropane carboxylic acid, indole-3-acetic acid and zeatin appeared to correlate with the measured oxidative indicators and with the expression of PsMAPK2. Globally, our results suggest a key role of H(2)O(2) in the coordination of pea seed germination, acting as a priming factor that involves specific changes at the proteome, transcriptome and hormonal levels.

Nutritional characteristics of proteins from the volva and pileus in cultivated mushroom Dictyophora rubrovolvata

Dictyophora rubrovolvata is one of the commercially important mushroom species in China. However, its volva and pileus account for about 65% of the whole mushroom (by fresh weight), and most of them are dumped without utilization. To effectively utilize the waste, the present study determined their proximate composition and investigated the nutritional characteristics of their proteins via the analysis of amino acid composition and protein fractionation. The results showed that the volva and pileus were rich in protein with 26.74% and 15.55% (dry basis), respectively. Predicted protein efficiency ratio values of proteins of the volva and pileus were 2.8 and 2.2, and the amino acid scores were 96 and 85.The albumin was the highest fraction both in the volva and pileus, accounting for 69.52% and 27.91% of the crude protein. The protein quality of the volva was therefore higher than that of the pileus. The volva might be developed as resource of high-quality vegetable-base protein.