Understanding the Relations Among the Storage, Soaking, and Cooking Behavior of Pulses: A Scientific Basis for Innovations in Sustainable Foods for the Future

Determination of Carbohydrate Composition in Lentils Using Near-Infrared Spectroscopy

Carbohydrates are the main components of lentils, accounting for more than 60% of their composition. Their content is influenced by genetic factors, with different contents depending on the variety. These compounds have not only been linked to interesting health benefits, but they also have a significant influence on the techno-functional properties of lentil-derived products. In this study, the use of near-infrared spectroscopy (NIRS) to predict the concentration of total carbohydrate, fibre, starch, total sugars, fructose, sucrose and raffinose was investigated. For this purpose, six different cultivars of macrosperm (n = 37) and microsperm (n = 43) lentils have been analysed, the samples were recorded whole and ground and the suitability of both recording methods were compared. Different spectral and mathematical pre-treatments were evaluated before developing the calibration models using the Modified Partial Least Squares regression method, with a cross-validation and an external validation. The predictive models developed show excellent coefficients of determination (RSQ > 0.9) for the total sugars and fructose, sucrose, and raffinose. The recording of ground samples allowed for obtaining better models for the calibration of starch content (R > 0.8), total sugars and sucrose (R > 0.93), and raffinose (R > 0.91). The results obtained confirm that there is sufficient information in the NIRS spectral region for the development of predictive models for the quantification of the carbohydrate content in lentils.

Sensory properties of selected biofortified common bean (Phaseolus vulgaris) varieties grown in Burundi

The dry common bean is an important grain legume used for human consumption worldwide. In Eastern Africa, Burundi has a significantly high per capita consumption of the crop. There has been significant research on the underlying agronomic traits of dry biofortified common beans, such as disease resistance. However, there is limited systematic information describing the sensory properties of these bean varieties, particularly in Burundi. This study evaluated the sensory properties of eight cooked dry biofortified common bean varieties using a panel of fifty-four (fourteen plus forty) persons for descriptive sensory evaluation and consumer acceptability tests. Kinure, a traditional non-biofortified common bean variety, was the control. Based on differences in the attributes of the bean varieties, two-dimensional principal component analysis (PCA) explained 58.94% of the variation. The attributes of astringency, consistency, color, juiciness, beany aroma, stickiness, and bean size contributed mostly to the differentiation of the bean varieties. A 95% PCA prediction ellipse displayed stronger congruity in the descriptive attributes of NUV130, NUV91, RWV1129, RWV1272, and RWR2245. In contrast, a deviation in the descriptive attributes of MAC44, MAC70, and RWR2154 was discerned. Regarding consumer acceptability tests, the varieties RWR2245 and MAC44 garnered significantly higher (p < .05) sensory scores on color, aroma, taste, texture, and overall acceptability. Therefore, the physical traits of cooked biofortified common bean varieties are a major contributor to varietal disparities in consumer acceptance studies. These parameters can greatly impact the adoption of dry biofortified common beans and could be of concern to common bean breeders.

Effect of cooking on structural changes in the common black bean (Phaseolus vulgaris var. Jamapa)

The cooking process is fundamental for bean consumption and to increase the bioavailability of its nutritional components. The study aimed to determine the effect of cooking on bean seed coat through morphological analyses with different microscopy techniques and image analyses. The chemical composition and physical properties of raw black bean (RBB) and cooked black bean (CBB) seeds were determined. The surface and cross-sectional samples were studied by Optical microscopy (OM), environmental scanning electron microscopy (ESEM), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The composition of samples showed significant differences after the cooking process. OM images and gray level co-occurrence matrix algorithm (GLCM) analysis indicated that cuticle-deposited minerals significantly influence texture parameters. Seed coat surface ESEM images showed cluster cracking. Texture fractal dimension and lacunarity parameters were effective in quantitatively assessing cracks on CBB. AFM results showed arithmetic average roughness (Ra) (121.67 nm) and quadratic average roughness (Rq) (149.94 nm). The cross-sectional ESEM images showed a decrease in seed coat thickness. The CLSM results showed an increased availability of lipids along the different multilayer tissues in CBB. The results generated from this research work offer a valuable potential to carry out a strict control of bean seed cooking at industrial level, since the structural changes and biochemical components (cell wall, lipids and protein bodies) that occur in the different tissues of the seed are able to migrate from the inside to the outside through the cracks generated in the multilayer structure that are evidenced by the microscopic techniques used.

Hard-to-cook phenomenon in common legumes: Chemistry, mechanisms and utilisation

Future dietary protein demand will focus more on plant-based sources than animal-based products. In this scenario, legumes and pulses (lentils, beans, chickpeas, etc.) can play a crucial role as they are one of the richest sources of plant proteins with many health benefits. However, legume consumption is undermined due to the hard-to-cook (HTC) phenomenon, which refers to legumes that have high resistance to softening during cooking. This review provides mechanistic insight into the development of the HTC phenomenon in legumes with a special focus on common beans and their nutrition, health benefits, and hydration behaviour. Furthermore, detailed elucidation of HTC mechanisms, mainly pectin-cation-phytate hypothesis and compositional changes of macronutrients like starch, protein, lipids and micronutrients like minerals, phytochemicals and cell wall polysaccharides during HTC development are critically reviewed based on the current research findings. Finally, strategies to improve the hydration and cooking quality of beans are proposed, and a perspective is provided.

Overview of the Incorporation of Legumes into New Food Options: An Approach on Versatility, Nutritional, Technological, and Sensory Quality

Consumers are more aware and demanding of healthy food options, besides being concerned with environment-friendly consumption. This paper aims to evaluate nutritional, technological, and sensory characteristics of legumes and their products' quality and versatility, considering potential applications in new food options. Legumes are foods that have a recognized nutritional group since they have high protein and fiber content. However, their consumption is still somehow limited for some reasons: in some countries it is not easy to find all the species or cultivars, they need an organization and planning before preparation since they need soaking, and there is the presence of antinutritional factors. Due to the different functionalities of legume proteins, they can be applied to a variety of foods and for different purposes, as grains themselves, aquafaba, extracts, flours, brans, and textured proteins and sprouts. These products have been inserted as ingredients in infant food formulations, gluten-free foods, vegetarian diets, and in hybrid products to reduce food costs as well. Foods such as bread, cakes, cookies, meat analogues, and other baked or cooked products have been elaborated with nutritional, technological and sensory quality. Further development of formulations focused on improving the quality of legume-based products is necessary because of their potential and protein quality.

Novel insights into the role of the pectin-cation-phytate mechanism in ageing induced cooking texture changes of Red haricot beans through a texture-based classification and in situ cell wall associated mineral quantification

Utilization of common beans is greatly hampered by the hard-to-cook (HTC) defect induced by ageing of the beans under adverse storage. Large bean-to-bean variations exist in a single batch of beans. Therefore, a texture-based bean classification approach was applied in this detailed study on beans with known textures, to gain in-depth insights into the role of the pectin-cation-phytate mechanism in relation to the texture changes during subsequent cooking of Red haricot fresh and aged beans. For the first time, a correlation between the texture (exhibited after cooking) of a single bean seed before ageing (fresh) and its texture after ageing was established. Furthermore, scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS) based in situ cell wall associated mineral quantification revealed that the cell wall associated Ca concentration was significantly positively correlated with the texture of both fresh and aged cooked Red haricot bean cotyledons, with ageing resulting in a significant enrichment of Ca at the cell wall. These additional Ca cations originate from intracellular phytate hydrolysis during ageing, which was shown to affect the texture distribution of aged beans during cooking significantly. The relocation of the mineral cations from the cell interior to the cell wall occurs mainly during storage rather than subsequent soaking of the cotyledons. In addition, the pectin-cation-phytate hypothesis of HTC was further confirmed by demethylesterification of the cell wall pectin and increased pectin-Ca interactions upon ageing of the cotyledons, finally leading to HTC development of the cotyledon tissue.

Soaking beans for 12 h reduces split percent and cooking time regardless of type of water used for cooking

Beans are one of the most important cheap source of protein in developing countries. However, their utilisation in the diets of many people remains limited due to long cooking time, among others. Therefore, it is imperative to identify ways to enhance utilisation of beans. The aim of the current study was to assess the effects of soaking and cooking in different types of water (tap, borehole, acidulated- 1.0 percent citric acid and soda- 0.2 percent sodium bicarbonate) on cooking time (CT), split percentage (SP) and total soluble solids (TSS) in broth of different varieties of beans. Results show that soaking significantly reduced CT across eight varieties from an average CT of 109.5–84.6 min in tap water, 109.5–85.2 min in borehole water, 115.9–92.7 min in acidulated water and 82.0–51.2 min in soda water representing 22.7%, 22.1%, 20.0% and 37.6% reduction in CT, respectively. Soaking generally decreased SP and varietal differences were observed suggesting beans are less likely to break when soaking precede cooking. Although cooking in soda water significantly reduced CT, unfortunately, it increased SP. Acidulated water extended CT but reduced SP in almost all varieties. Soaking generally decreased TSS in broth from 7.0 to 6.7% in tap water, 6.1–5.8% in borehole water and 11.3–7.7% in soda water while it increased TSS in acidulated water from 18.2 to 20.6% across all the eight varieties which suggest reduction in leaching out of bean solids into cooking water which is consistent with reduced SP of soaked beans. While use of soda water reduced cooking time and therefore saved time and energy, its effect of increasing split percent may not be appealing to some consumers. This study has demonstrated that bean soaking significantly reduced cooking time and split percent and these can also be affected by type of cooking water.

Flavor formation and regulation of peas (Pisum sativum L.) seed milk via enzyme activity inhibition and off-flavor compounds control release

Ascorbic acid, quercetin, epigallocatechin-3-gallate and reduced glutathione as well as high hydrostatic pressure were used to regulate the flavor of milk prepared from pea seeds. Activities of lipoxygenase (LOX) pathway enzymes and fatty acid contents of pea milk were determined. The hexanal content was positively correlated with the activity of LOX-2, but was negatively correlated with the contents of linoleic acid and α-linolenic acid. The intensity of the sensory attribute "fatty" was reduced when epigallocatechin-3-gallate or high hydrostatic pressure were combined with quercetin. Decreases in hexanal, pentanol, and 2-pentylfuran contents may have caused the change in sensory properties of pea milk. Pea protein, sodium sulfate and/or propylene glycol were used to regulate interactions between pea protein and flavor compounds. The hexanal content was reduced by commercial pea protein. Sodium sulfate and propylene glycol individually reduced the hexanal content and together reduced the hexanol content.

Transcriptome-Guided Identification of Pectin Methyl-Esterase-Related Enzymes and Novel Molecular Processes Effectuating the Hard-to-Cook Defect in Common Bean (Phaseolus vulgaris L.)

The hard-to-cook defect in common beans is dictated by the ability to achieve cell separation during cooking. Hydrolysis of pectin methyl-esters by the pectin methyl-esterase (PME) enzyme influences cell separation. However, the contributions of the PME enzyme and the cell wall to the hard-to-cook defect have not been studied using molecular tools. We compared relevant molecular processes in fast- and slow-cooking bean varieties to understand the mechanisms underpinning the hard-to-cook defect. A PME spectrophotometric assay showed minor differences in enzyme activity between varieties. Meanwhile, a PME HMMER search in the P. vulgaris genome unveiled 113 genes encoding PMEs and PME inhibitors (PMEIs). Through RNA sequencing, we compared the gene expression of the PME-related genes in both varieties during seed development. A PME (Phvul010g080300) and PMEI gene (Phvul005g007600) showed the highest expression in the fast- and slow-cooking beans, respectively. We further identified 2132 differentially expressed genes (DEGs). Genes encoding cell-wall-related enzymes, mainly glycosylphosphatidylinositol mannosyltransferase, xyloglucan O-acetyltransferase, pectinesterase, and callose synthase, ranked among the top DEGs, indicating novel relations to the hard-to-cook defect. Gene ontology mapping revealed hydrolase activity and protein phosphorylation as functional categories with the most abundant upregulated DEGs in the slow-cooking bean. Additionally, the cell periphery contained 8% of the DEGs upregulated in the slow-cooking bean. This study provides new insights into the role of pectin methyl-esterase-related genes and novel cell wall processes in the occurrence of the hard-to-cook defect.

Seed Moisture Isotherms, Sorption Models, and Longevity

Seed moisture sorption isotherms show the equilibrium relationship between water content and equilibrium relative humidity (eRH) when seeds are either losing water from a hydrated state (desorption isotherm) or gaining water from a dry state (adsorption isotherm). They have been used in food science to predict the stability of different products and to optimize drying and/or processing. Isotherms have also been applied to understand the physiological processes occurring in viable seeds and how sorption properties differ in relation to, for example, developmental maturity, degree of desiccation tolerance, or dormancy status. In this review, we describe how sorption isotherms can help us understand how the longevity of viable seeds depends upon how they are dried and the conditions under which they are stored. We describe different ways in which isotherms can be determined, how the data are modeled using various theoretical and non-theoretical equations, and how they can be interpreted in relation to storage stability.

Sensory descriptors for pulses and pulse-derived ingredients: Toward a standardized lexicon and sensory wheel

The organoleptic quality of pulses and their derived ingredients is fundamental in human utilization and evolution of food. However, the widespread use of pulses is hindered by their inherent sensorial aspects, which are regarded as atypical by the consumers who are unfamiliar to them. In most studies involving sensory assessment of pulses and pulse-ingredients using classical descriptive analysis methods, assessors establish their own lexica. This review is a synthesis of descriptive terms by which sensations emanating from pea, chickpea, lentil, faba bean, dry bean, bambara groundnut, lupin, pigeon pea and cowpea, and their derived ingredients have been described in the literature. Studies involving sensory assessment of processed whole seeds, slurries of raw flour, slurries of protein extracted from raw flour, and food products containing components of pulses were considered. The terms are categorized into those denoting basic taste, aroma, flavor, and trigeminal sensations. Bitterness is the most widely perceived basic taste. Beany, which is broad and complex with subcharacter notes, is predominantly used to describe aroma and flavor. The frequency of use of the collated terms in the reviewed studies was used to establish a sensory wheel. Inconsistency in the use of descriptive terms in the literature necessitates establishment of a standard lexicon that can be applied in both classical and increasingly popular rapid descriptive methods (e.g., check-all-that-apply) throughout the pulse value chain. This review is timely considering the dominance of pulses in plant-based foods and their increasing appeal to the food industry.

Aquafaba from Korean Soybean II: Physicochemical Properties and Composition Characterized by NMR Analysis

Aquafaba (AQ) emulsification properties are determined by genetics and seed processing conditions. The physicochemical properties and hydration rates of chickpea (CDC Leader) as a control with proven emulsifying properties were recently reported. Here, we identify correlations between soybean (Backtae, Seoritae, and Jwinunikong) physical, chemical, and hydration properties as well as AQ yield from seed and functional (emulsion and foaming) properties. In addition, a total of 20 compounds were identified by NMR including alcohols (isopropanol, ethanol, methanol), organic acids (lactic acid, acetic acid, succinic acid, citric acid, and malic acid), sugars (glucose, galactose, arabinose, sucrose, raffinose, stachyose), essential nutrients (choline, phosphocholine), amino acids (alanine, glutamine), and polyphenols (resveratrol, glycitin). The process used in this study utilizes a soaking step to hydrate the seed of the selected Korean soybean cultivars. The product, AQ, is an oil emulsifier and foaming agent, which is suitable for use as an egg substitute with improved emulsion/foam formation properties when compared with a chickpea-based AQ.

How postharvest variables in the pulse value chain affect nutrient digestibility and bioaccessibility

Pulses are increasingly being put forward as part of healthy diets because they are rich in protein, (slowly digestible) starch, dietary fiber, minerals, and vitamins. In pulses, nutrients are bioencapsulated by a cell wall, which mostly survives cooking followed by mechanical disintegration (e.g., mastication). In this review, we describe how different steps in the postharvest pulse value chain affect starch and protein digestion and the mineral bioaccessibility of pulses by influencing both their nutritional composition and structural integrity. Processing conditions that influence structural characteristics, and thus potentially the starch and protein digestive properties of (fresh and hard-to-cook [HTC]) pulses, have been reported in literature and are summarized in this review. The effect of thermal treatment on the pulse microstructure seems highly dependent on pulse type-specific cell wall properties and postharvest storage, which requires further investigation. In contrast to starch and protein digestion, the bioaccessibility of minerals is not dependent on the integrity of the pulse (cellular) tissue, but is affected by the presence of mineral antinutrients (chelators). Although pulses have a high overall mineral content, the presence of mineral antinutrients makes them rather poorly accessible for absorption. The negative effect of HTC on mineral bioaccessibility cannot be counteracted by thermal processing. This review also summarizes lessons learned on the use of pulses for the preparation of foods, from the traditional use of raw-milled pulse flours, to purified pulse ingredients (e.g., protein), to more innovative pulse ingredients in which cellular arrangement and bioencapsulation of macronutrients are (partially) preserved.

Microscopic evidence for pectin changes in hard-to-cook development of common beans during storage

In this study, pectin changes during Red haricot bean storage under high temperature and high humidity conditions were investigated to understand the hard-to-cook (HTC) development from a microstructural point of view. First, to ensure repeatability of the microscopy results, a classification of the fresh and stored beans (aged at 35 °C and 83% relative humidity) into different hardening levels (the Non-aged, Aged and Very-hard aged sample) was performed based on the texture values of cooked half-cotyledons. Cell wall strength of the cotyledons was evaluated, showing that the aged samples (HTC seeds) exhibit stronger cell walls with more/stronger pectic cross-linkages than the Non-aged sample. After a sequential pectin extraction aiming at removing pectin fractions of different solubility, cell wall autofluorescence and immunolabeling of JIM7, LM9 and 2F4 epitopes in the residual materials were examined. Upon ageing, the samples exhibited an increased Ca²⁺-pectin and ferulic acid-pectin crosslinking, these pectic complexes being accumulated primarily at the intercellular spaces. The results suggest a contribution of both the pectin-cation-phytate hypothesis and the involvement of phenolic-pectin crosslinks in HTC development at the cotyledon during storage of common beans.

Bambara Groundnut: An Underutilized Leguminous Crop for Global Food Security and Nutrition

Rapid population growth, climate change, intensive monoculture farming, and resource depletion are among the challenges that threaten the increasingly vulnerable global agri-food system. Heavy reliance on a few major crops is also linked to a monotonous diet, poor dietary habits, and micronutrient deficiencies, which are often associated with diet-related diseases. Diversification-of both agricultural production systems and diet-is a practical and sustainable approach to address these challenges and to improve global food and nutritional security. This strategy is aligned with the recommendations from the EAT-Lancet report, which highlighted the urgent need for increased consumption of plant-based foods to sustain population and planetary health. Bambara groundnut (Vigna subterranea (L.) Verdc.), an underutilized African legume, has the potential to contribute to improved food and nutrition security, while providing solutions for environmental sustainability and equity in food availability and affordability. This paper discusses the potential role of Bambara groundnut in diversifying agri-food systems and contributing to enhanced dietary and planetary sustainability, with emphasis on areas that span the value chain: from genetics, agroecology, nutrition, processing, and utilization, through to its socioeconomic potential. Bambara groundnut is a sustainable, low-cost source of complex carbohydrates, plant-based protein, unsaturated fatty acids, and essential minerals (magnesium, iron, zinc, and potassium), especially for those living in arid and semi-arid regions. As a legume, Bambara groundnut fixes atmospheric nitrogen to improve soil fertility. It is resilient to adverse environmental conditions and can yield on poor soil. Despite its impressive nutritional and agroecological profile, the potential of Bambara groundnut in improving the global food system is undermined by several factors, including resource limitation, knowledge gap, social stigma, and lack of policy incentives. Multiple research efforts to address these hurdles have led to a more promising outlook for Bambara groundnut; however, there is an urgent need to continue research to realize its full potential.

Genetic variability of cooking time in dry beans (Phaseolus vulgaris L.) related to seed coat thickness and the cotyledon cell wall

Dry beans are an affordable, nutritious food that often require long cooking times. Storage time and conditions, growing environment, and genotype influence cooking times. Little is known about factors underlying genetic variation for cooking time. Using fast and slow cooking genotypes from four different seed types (brown, cranberry, red mottled, yellow), the objectives of this study were to (1) characterize genetic variability for cooking time across multiple soaking time points; (2) determine the roles of seed coat and cotyledon cell wall physical traits in genetic variability for cooking time; and (3) identify seed coat and cotyledon cell wall compositional differences associated with genetic variability for cooking time. Genotypes were evaluated for cooking time on unsoaked beans and beans soaked for 3, 6, 12, 18, and 24 h. Cooking times were sharply reduced after 3 h of soaking and plateaued after 6 h of soaking. Interestingly, the genotypes in each pair that cooked faster when soaked did not necessarily cook faster when unsoaked. Greater seed coat percentage, cotyledon cell wall thickness, total and insoluble whole seed dietary fiber, and insoluble cotyledon cell wall isolate were genotypic factors associated with longer cooking times of soaked beans. Thicker seed coat macrosclereid- and osteosclereid-layers were genotypic factors associated with longer cooking times of unsoaked beans. These findings suggest that cotyledon cell wall thickness and composition have a significant role in genetic variability for cooking time of soaked beans and seed coat layer thickness relates to the genetic variability for cooking time of unsoaked beans.