Bioactivity of endosperm extracts from susceptible and resistant bean seeds against Callosobruchus maculatus

Due to their high nutritional value, seeds are often the target of herbivory. In response, plants have evolved a host of adaptations that physically and/or chemically reduce the likelihood of granivory. In grain legumes, the main chemical defences within the endosperm derive from anti-nutritional proteins such as lectins and protease inhibitors. However, less is known about the bioactivity of secondary metabolites found within seeds. Here, solvent extraction was used to identify the major classes of phytochemicals found within the endosperm of both resistant beans (Phaseolus vulgaris) and susceptible beans (Vigna unguiculata). Phenols and terpenoids were recovered from the resistant P. vulgaris seeds only, whilst glycosides and flavonoids were recovered in greater amounts from P. vulgaris in comparison to V. unguiculata. To assess the bioactivity of the extracts against the seed beetle, Callosobruchus maculatus, the extracts were incorporated into artificial seeds and key life-history traits of the beetle determined. The results show the endosperm of both resistant and susceptible beans to contain an ensemble of secondary metabolites that deter oviposition (antixenosis) by adult beetles and disrupt the survival and development of the larvae (antibiosis). However, no extract resulted in complete resistance, indicating that the phytochemicals function alongside other anti-herbivory mechanisms such as α-amylase inhibitors and protease inhibitors. Breeding programmes could potentially select for key phytochemical groups such as terpenoids or glycosides in cultivars in order to optimise the trade-off between resistance and agronomic quality by harnessing the anti-herbivory properties of secondary metabolites in conjunction with anti-nutritional proteins.     

Identification,biochemical characterization and biological role of defense proteins from common bean genotypes seeds in response to Callosobruchus maculatus infestation

Common bean is a legume of significant socioeconomic importance and is cultivated worldwide. This crop is affected by several pests and diseases, which cause considerable economic losses and reduce yield. In recent years, several studies have demonstrated the role of proteins and peptides with activity against a wide range of insects and pathogens. The objective of this work was to identify defense proteins, such as antimicrobial peptides, protease and amylases inhibitors in common bean genotypes and evaluate the relationship of these proteins with Phaseolus vulgaris seed resistance to Callosobruchus maculatus infestation. Nineteen common bean genotypes were subjected to protein extraction, pH 5.4, and precipitation with ammonium sulfate at 70% saturation. The obtained extracts were separated by tricine gel electrophoresis. Experiments were carried out with natural seeds of common beans and artificial seeds (Vigna unguiculata seeds covered with seed coats of common beans) to evaluate the rate of oviposition and development of the insect species Callosobruchus maculatus. Lipid-transfer proteins were identified in nine genotypes whereas defensins were present in all genotypes. The inhibitory activity of α-amylases and trypsin and fungal development were determined in crude extracts (50 μg mL⁻¹). The results also indicated that the extracts from all bean genotypes inhibited the activity of human salivary α-amylase and C. maculatus larval α-amylase. Except for the extracts of four genotypes, all other extracts inhibited trypsin activity. None of the extracts from the evaluated bean genotypes inhibited the growth of tested fungi. Natural seeds from all genotypes did not inhibit insect oviposition, however, the larvae did not survive after feeding on these seeds. Artificial seeds containing seed coat flour of all genotypes inhibited the oviposition of C. maculatus, indicating that the seed coat was also repellent to insect.     

Correlation between biophysical seed characteristics of rice bean,Vigna umbellata (Fabaceae: Faboideae: Phaseoleae) and the development of Callosobruchus maculatus (Coleoptera: Chrysomelidae: Bruchinae)

The bruchid, Callosobruchus maculatus is a serious pest of stored pulses. Four biophysical seed characteristics viz. Seed size, texture of seed surface, thickness of seed coat and seed hardness of 10 genotypes of rice bean, a wild pulse crop were investigated for assessing mechanism of resistance against C. maculatus. Oviposition preference and larval penetration in seed coat did not differ significantly among different test genotypes. Highest number of larvae which developed up to last larval/pupal instar were observed in susceptible check variety of mungbean, PAU 911 (30.00) and lowest in rice bean genotype, LRB 535 (0.83). Highest and lowest seed weight was noticed in rice bean genotype, LRB 529 (6.81 g) and PAU 911 (3.88 g), respectively. Almost similar seed coat thickness was recorded among different test genotypes. Maximum seed hardness was noted in genotype LRB 507 (6.45 kg) whereas minimum in PAU 911 (2.00 kg) among all test genotypes. Any remarkable correlation of biophysical seed characteristics of test genotypes with ovipositon, larval penetration and development of C. maculatus was not observed. Thus, biophysical seed characteristics of rice bean did not suggest to play a vital role in imparting resistance against C. maculatus.     

Seed coat has no value in protecting cowpea seed against attack by Callosobruchus maculatus (F.)

Experiments were conducted to compare the oviposition preference of the cowpea seed beetle Callosobruchus maculatus (F.) on 22 cowpea varieties, with and without seed coat. The cowpeas included five resistant, four moderately resistant and 13 susceptible varieties. Ten of the varieties had smooth seed coats while 12 were wrinkled. Mean numbers of eggs laid on smooth and wrinkled varieties were not significantly different. The survival of the bruchid was also assessed on intact and decorticated seeds of five varieties, comprising two resistant varieties “Kanannado” and “IT89KD-288”, a moderately resistant variety “IT93K-513-2” and two susceptible varieties “IT87K-941-1” and “IT89KD-374-57”. There was no correlation of resistance level with the number of eggs oviposited on cowpea varieties. Under limited and free-choice conditions, cowpea seeds with intact seed coats were preferred to decorticated seeds for oviposition. Adult emergence, mean development periods and pre-adult mortality were similar when seed coats were removed or left intact. It is concluded that the seed coat may not be a useful aspect to consider for breeding of bruchid resistance into cowpea varieties.     

Antioxidant properties of legumes and their morphological fractions as affected by cooking

The antioxidant properties of 6 legumes: green gram (Vigna radiate), red kidney beans (Phaseolus vulgaris), chickpea (Cicer arietinum), red lentil (Lens esculenta), soybean (Glycine max), and moth beans (V. aconitifolia), and their morphological fractions were evaluated before and after cooking. Kidney beans had the highest total phenolic content (8.9 mg ferulic acid equivalents/g), DPPH free radical scavenging activity (38.1%), reducing power (85.5 μmol ascorbic acid equivalents/g), and total flavonoid content (0.9 mg catechin equivalents/g). Highest metal chelating activity was observed for moth beans (93.3%). The antioxidant properties of the seed coat in all the legumes were manifold higher as compared to the whole legume or its respective endosperm and removal of the seed coat significantly reduced the antioxidant activity. Although cooking brought about a reduction in the antioxidant activity of the legumes in majority of the legumes and their fractions, an increase in the metal chelating activity was observed.     

Deterrent and insecticidal properties of bean seed (Phaseolus vulgaris L.) whole meal or protein extract incorporated into the diet of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Callosobruchus maculatus, a pest that causes serious damage to chickpea Cicer arietinum, cannot develop in the seeds of Phaseolus or Vigna spp. which contain lectins. The insecticidal activity towards C. maculatus in these seeds is attributed both to lectins with specific affinity to N-acetylglucosamine, the major component of insect chitin, and to alpha-amylase inhibitors (lectin-like proteins). The insecticidal properties of bean meal or bean protein extracts from different sources towards different pest species are variable and need to be experimentally evaluated. The main objective of this study was to determine through a feeding trial on artificial chickpea seed the potential of bean seed meal from a wild bean Vigna caracalla, four varieties of Phaseolus vulgaris, and of a protein extract of P. vulgaris seed, to alter different life history traits of C. maculatus. The chickpea weevil was set up on artificial chickpea seeds containing different amounts of bean meal to observe the effects on female oviposition, percentage of development to adulthood and juvenile development time. These traits were combined in a composite index measuring the alteration of the multiplication rate of C. maculatus fed on artificial seed. The activity of lectin-like extracts was observed on chickpea artificial seed spiked with bean seed extract. Incorporation of bean flour at a rate of 10 and 20% in chickpea artificial seed significantly decreased C. maculatus female fecundity, percentage of adult emergence, and greatly increased the development time. Feeding trials with protein extracts of P. vulgaris reduced fecundity and survival of C. maculatus. Incorporation of 10% V. caracalla bean seed meal in chickpea artificial seed, reduced the multiplication potential of C. maculatus by over 90% showing that bean seed lectin extracts are worthy of further investigation for post-harvest infestation control.     

Chemical basis for the low sensory perception of the Ganxet bean (Phaseolus vulgaris) seed coat

The Ganxet bean (Phaseolus vulgaris L), highly appreciated in Catalan gastronomy, has a higher proportion of seed coat than other beans (eg White Kidney or Faba Asturiana); however, general diners and sensory tests point out a lower perception of this seed coat. The differences in chemical composition between Ganxet, White Kidney and Faba Asturiana beans, before and after cooking, were established and related to perceived sensory differences in seed coat content. Ganxet's higher absolute and percentage losses of total dietary fibre (19.5%), soluble dietary fibre (32.5%), cellulose (25.6%) and pectins (38.1%) break down the consistency of the seed coat during cooking, which would explain its low sensory perception. The high loss of cellulose during cooking could be due to its partial combination with proteins, which would aid its breakdown. © 2002 Society of Chemical Industry     

Protein and starch content of raw,soaked and cooked beans (Phaseolus vulgaris L.)

Organoleptic qualities are an important factor in the market value of legumes, especially in developed countries. Unfortunately, the molecules that have the greatest influence on the texture of beans undergo important transformations during soaking and cooking. Moreover, the extent to which these changes are linear is unknown, making uncertain the use of raw beans in chemical screenings for sensory properties. Results of our experiments show that the amount of protein and amylose present in raw beans provides a good indicator of these substances in cooked beans (correlation coefficients between raw and cooked beans = 0.91, p ? 0.001 and 0.87, p ? 0.01, respectively). The Mg content in the raw seed coat also shows a strong correlation with that found in the cooked seed coat (r = 0.86, p ? 0.01). The correlations found for the other traits are weaker, indicating that the evaluation of raw samples is not predictive of the findings in cooked beans.     

Characterization of new sources of mungbean (Vigna radiata (L.) Wilczek) resistance to bruchids, Callosobruchus spp. (Coleoptera: Bruchidae)

The bruchid beetles Callosobruchus chinensis (L.) and C. maculatus (F.) are destructive pests of stored mungbean (Vigna radiata (L.) Wilczek). The development of resistant mungbean varieties to manage bruchids is a major breeding objective. In the present study, we investigated the characteristics of resistance to C. chinensis and C. maculatus in two new resistant mungbean accessions V1128 and V2817, and two previously reported resistant accessions V2709 and V2802, compared to the susceptible mungbean cultivar, KPS1. Evaluation for resistance to both bruchid species using whole and decorticated seeds revealed that V1128 and V2817 were free from damage, V2709 and V2802 showed partial damage with low or moderate number of bruchids emerging from seeds, and KPS1 showed complete damage with the highest number of bruchids emerged. Comparison of the seeds harvested at seed filling, early maturity and full maturity stages revealed that the percentage of damaged seeds from resistant accessions was lower at all stages compared with KPS1. V1128 and V2817 showed complete resistance against both bruchids regardless of when their seeds were harvested, while resistance in V2709 and V2802 were most pronounced at full maturity, and KPS1 was totally damaged at all times tested. These results suggest that the chemical factor(s) conferring resistance is synthesized as early as the seed filling stage. Evaluation of resistance using artificial seeds showed that increasing the percentage of resistant seed powder adversely affected bruchid growth and development. The number of adults emerging from seeds and number of damaged seeds decreased while adult developmental period increased as the proportion of resistant seed powder increased. The weight of emerging male and female adults of C. maculatus was lighter than those from the seeds containing susceptible seed powder alone. However, C. chinensis adults were not affected by the same test. The results suggest that biochemical(s) in cotyledon tissue are responsible for the resistance and the seed coat had no protective role against the bruchids. Although all four resistant accessions evaluated are useful for mungbean breeding, V1128 and V2817 show complete resistance to both C. chinensis and C. maculatus. Thus, these two new resistant sources may be the most effective for breeding purposes.     

Fractionation by gel exclusion HPLC of proteins from acidic and alkaline extractions of Phaseolus beans

The proteins extracted from Phaseolus vulgaris (white kidney, navy) beans and P. lunatus (baby lima, large lima) beans by sodium hydroxide (NaOH) solution and citric acid (CA) solutions were fractionated by gel exclusion high-pressure liquid chromatography. The isoelectric amorphous proteins from the NaOH extraction and bipyramidal crystalline and spheroidal proteins from the CA extractions were also fractionated. Both the NaOH and the CA extracts of the beans contained 8–10 fractions. The proteins isolated from the extracts of the P. vulgaris beans were comprised predominantly of a relatively large molecular weight fraction, regardless of the microstructure of the protein precipitate; several of the fractions which were relatively major components of the extracts were not found in the precipitates obtained from the extracts. The differences in behaviour between the extracts and protein isolates of the different beans might be related to genetic variations.     

Automatic, rapid screening of seed resistance in cowpea, Vigna unguiculata (L.) Walpers, to the seed beetle Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) using acoustic monitoring

The biomonitor technique was investigated as a rapid and automatic method for measuring the resistance of cowpea varieties to the seed beetle Callosobruchus maculatus. This technique measures the activity of internally feeding insect larvae by counting ultrasonic emissions produced as they feed. Activity throughout the development of C. maculatus larvae in known susceptible and resistant cowpea varieties was recorded. This showed details of the development of each larval instar, and showed clear differences between the resistant and susceptible cowpeas. A rapid method for comparing cowpeas was proposed in which the activity of larvae was recorded for 24 h starting 14 days after oviposition. Using this method, significant differences in activity were apparent between one susceptible and two resistant cowpea varieties. Further comparisons using a randomised block experimental design also showed a clear difference in activity between one susceptible and one known resistant cowpea variety. This experimental protocol took 21 days. It is suggested that the biomonitor offers a promising method for screening seeds for resistance to insect pests with a reduction in the time and effort required over conventional bioassay methods.     

Seed coat and variety of peanut inhibits host preference and development of Oryzaephilus mercator

Oryzaephilus mercator (Fauvel) (Coleoptera: Silvanidae) is a postharvest pest of stored peanuts (Arachis hypogea L.). Although it is only a secondary pest, this insect causes extensive damage and reduces the quantity and quality of peanut kernels. The objective of this research was to study whether host preference and development of O. mercator differ depending on the variety of peanut and/or on whether the peanut retains its seed coat or is bare. We used three varieties of peanut (Kelinci, Bison and Takar1) separating out each variety into groups with or without a seed coat. In the laboratory, we conducted two separate studies examining host preference and development of O. mercator. Host preference was studied using a preference cage consisting of six chambers for all peanut varieties with and without seed coat and each cage contained 15 mating pairs of O. mercator. The development study was conducted by placing 15 mating pairs of O. mercator into a treatment jar and allowing them to feed on different peanut varieties with and without a seed coat. Results from the host preference study indicated that O. mercator preferred bare kernels of the Kelinci variety over other peanut varieties both as a food source and for oviposition. During the development experiment, we observed that O. mercator experienced faster development time when exposed to bare kernels of all three varieties tested as opposed to those with intact seed coat. Results show that peanuts with a seed coat and variety with high kernel hardness (Bison variety) deters predation and inhibits host preference and development of O. mercator.     

Genetics of bruchid (Callosobruchus maculatus Fab.) resistance in cowpea (Vigna unguiculata (L.) Walp.)

Bruchid resistance has been measured using a variety of techniques. Mean development period (MDP) and percentage adult emergence (PAE) are two of the more important traits measuring bruchid (Callosobruchus maculatus Fab.) resistance in cowpea. The objective of the study was to evaluate the genetic relationship between MDP and PAE in C. maculatus resistant cowpea. Seventy-two F₂ population plants were developed from the cross between C. maculatus resistant TVu-11953 (with delayed MDP and low PAE) and C. maculatus susceptible Ife Brown (with early MDP and high PAE) which were evaluated for resistance to cowpea C. maculatus. MDP at 45 days after infestation (DAI) and PAE at 60 DAI were taken as analysed measures for resistance to C. maculatus infestation. Data generated were subjected to chi-square analysis. Varied resistant response to C. maculatus infestation was observed among the F₂ generation plants but their responses showed inclination to the susceptible parent. A 15:1 ratio for susceptible to resistant genotypes was observed with MDP among the F₂ genotypes evaluated which is an indication of the presence of two recessive genes that control of MDP. The segregation of PAE also showed a 15:1 ratio goodness of fit (P > 0.05) for susceptible to resistant genotypes. Test of independence between MDP and PAE was not significant (χ² = 2.19, P = 0.19). This study revealed that the recessive genes controlling these two traits (MDP and PAE) were independently assorted and showed no linkage. This was also evident in the observed F₂ genotypes with C. maculatus resistance expressing either delayed MDP or low PAE and not both in the study.     

Evaluation of the antioxidant and antiproliferative activities of extracted saponins and flavonols from germinated black beans (Phaseolus vulgaris L.)

Flavonoids and saponins from common beans have been widely studied due to their bioactivity. This research evaluated the effect of germination of black beans (Phaseolus vulgaris L.) on the antioxidant capacity and antiproliferative activity against cancer cell lines of saponins and flavonoids extracted from seed coats, cotyledons and sprouts. Principal component analysis was performed to achieve punctual associations between the black bean saponins and flavonoids concentrations to the antioxidant capacity and the antiproliferative activities. Total phenolic content and antioxidant capacity of extracts were higher when obtained from seed coats, mainly from the 3rd germination day. The extracts obtained from seed coats after 3 and 5 germination days inhibited all cancer cell lines proliferation with no cytotoxicity against control cells. Genistein was related with the activity against mammary cancer cells but flavonols and group B saponins were more related with hepatic and colon cancers. Non-glycosilated flavonols were related with antioxidant capacity.     

Physiological traits related to terminal drought resistance in common bean (Phaseolus vulgaris L.)

BACKGROUND: A major problem in common bean (Phaseolus vulgaris L.) agriculture is the low yield due to terminal drought. Because common beans are grown over a broad variety of environments, the study of drought‐resistant genotypes might be useful to identify distinctive or common mechanisms needed for survival and seed production under drought. RESULTS: In this study the relationship between terminal drought resistance and some physiological parameters was analysed using cultivars contrasting in their drought response from two different gene pools. Trials were performed in three environments. As expected, drought treatments induced a decrease in leaf relative humidity and an increase in leaf temperature; however, when these parameters were compared between susceptible and resistant cultivars under optimal irrigation and drought, no significant differences were detected. Similar results were obtained for chlorophyll content. In contrast, analysis of relative water content (RWC) and stomatal conductance values showed reproducible significant differences between susceptible and resistant cultivars grown under optimal irrigation and drought across the different environments. CONCLUSIONS: The data indicate that drought‐resistant cultivars maximise carbon uptake and limit water loss upon drought by increasing stomatal closure during the day and attaining a higher RWC during the night as compared with susceptible cultivars, suggesting a water balance fine control to achieve enough yield under drought. Copyright © 2012 Society of Chemical Industry     

Susceptibility of selected maize seed genotypes to Sitophilus zeamais (Coleoptera: Curculionidae)

Studies were carried out under laboratory conditions of 25 ± 2 °C and 70 ± 5% RH in an incubator to determine the relative susceptibility of eighteen maize genotypes to attack by the maize weevil, Sitophilus zeamais Motschulsky. The experiment was laid out in a Completely Randomized Design (CRD) with three replications. Adult mortality, number of F₁ progeny, weevil development time, susceptibility index, percentage seed damage, percentage weight loss, and weight of powder produced were determined after storage period of three months. The susceptibility index was determined using Dobie’s formula and the genotypes were classified into different susceptibility groups. The genotypes exhibited varying degrees of susceptibility to S. zeamais attack. Only Aseda was regarded as resistant and TZE-Y POP STR as moderately resistant to S. zeamais. Kpari-Faako, Tintim, WACCI-M-1215, WACCI-M-1594 and Wang-Dataa were regarded as moderately susceptible to S. zeamais. However, Abontem, Bihilifa, Ewul-Boyu, Sanzal-Sima, TZE-I 17, WACCI-M-1205, WACCI-M-1508 and WACCI-M-1510 were regarded as susceptible genotypes. Furthermore, Aburohemaa, Obaatanpa and Omankwa were regarded as highly susceptible to S. zeamais. Number of F₁ progeny, seed damage, seed weight loss, weight of dust produced and seed moisture content had positive relationship with varietal susceptibility while adult weevil mortality, median development period and seed germination after infestation had an inverse relationship with susceptibility in maize. The use of insect resistant genotypes would offer a sustainable way of minimizing postharvest losses of seeds in storage especially for smallholder farmers who keep harvested grains for future use as food and seed.     

Effect of various processing techniques on digestibility of starch in Red kidney bean (Phaseolus vulgaris) and two varieties of peas (Pisum sativum)

The effect of common domestic processing methods, such as splitting, soaking, boiling and pressure-cooking on the nutritionally significant starch fractions such as rapidly and slowly digestible starches (RDS and SDS), resistant starch (RS) and total starch (TS) in two legumes, Red kidney bean (Phaseolus vulgaris) and Yellow and Green peas (Pisum sativum) were studied. The legumes had comparatively high amount (>30%, dry basis) of RS. Soaking of all legumes resulted in reduced starch fractions, possibly due to leaching of soluble fractions. Ordinary cooking of soaked as well as unsoaked seeds led to a significant (P < 0.01) decrease in RS and increase in RDS, SDS and TS. Pressure-cooking led to even greater reduction in RS and a greater increase in RDS. Cooking of legumes gelatinizes the starch and opens up the starch structure which makes them vulnerable to α-amylase hydrolysis. Splitting of legumes markedly affects the digestibility as well as RS content of raw as well as processed legumes indicating that the seed coat plays a key role in the digestibility of starches in these seeds. Overall, the enzyme resistant starch fraction of legumes was rendered more digestible by all the domestic cooking methods used.     

Antibiosis levels of common bean genotypes toward Zabrotes subfasciatus (Boheman) (Coleoptera: Bruchidae) and its correlation with flavonoids

Expression of the antibiosis-resistance category to weevils has been evaluated in several bean genotypes with very promising results. Among the several causes responsible for this resistance category the arcelin protein and trypsin inhibitors stand out. Other mechanisms may be associated with plant resistance to the attack of weevils; however, few studies seek to discover these possible causes. Thus, our research aimed at identifying bean genotypes resistant to Zabrotes subfasciatus, classify them into resistance levels, quantify the content of flavonoids, and correlate it with data obtained from the genotypes. An antibiosis test was performed with beans of 43 genotypes and 40 replications (bean grains) under a completely randomized design. The biological parameters recorded from Z. subfasciatus were the periods from egg to larvae, larvae to adult, egg to adult, longevity and life cycle, in addition to egg viability, adults emerged, susceptibility relative index, adult weight, sex ratio, and the dry mass consumed by larvae. The chemical profile of flavonoids from each genotype was assessed by means of LC-MS. Based on the results of the weevil biological parameters and dry mass consumed provided by univariate and multivariate statistical analyses, the bean genotypes were classified into four levels of resistance (antibiosis): highly resistant, moderately resistant, susceptible and highly susceptible. Among the evaluated flavonoids, we could identify isoquercitrin; however, it has no correlation with the expression of resistance. From the results obtained in this work, more studies will be conducted with the genotypes that stood out as resistant, evaluating other resistance categories and defense mechanisms of these materials against the attack of Z. subfasciatus and other pests, as well as studies of other important agronomic characteristics aiming at future commercialization of the bean genotypes.     

Tryptic fragments of phaseolin from protein isolates of Phaseolus beans

Crystalline and amorphous protein isolates from white kidney and navy beans (Phaseolus vulgaris) and baby lima and large lima beans (Phaseolus lunatus) were subjected to tryptic hydrolysis. The hydrolysis was monitored by the nitrogen solubility index (NSI) and reverse phase-high performance liquid chromatography/mass spectrometry (RP-HPLC/MS) analysis of the hydrolysates. The results of the NSI and RP-HPLC showed that the tryptic fragments of the crystalline isolates possessed higher solubility properties than the fragments of the amorphous isolates. The results of the MS study of phaseolin peptides in the RP-HPLC fractions of the hydrolysates showed that trypsin-specific bonds located in β-structured regions of β-phaseolin are resistant to tryptic hydrolysis, and that the most susceptible bonds to trypsin hydrolysis are located in regions not directly involved in the formation of secondary structural units, but in regions of disordered structure, or in regions interconnecting secondary structural units. Some trypsin-specific bonds located within α-helical structures were also cleaved by trypsin hydrolysis.     

Use of Seed Sprouting in Modification of Food Nutrients and Pasting Profile of Tropical Legume Flours

The study investigates the effect of seed sprouting on minerals, anti nutrients and pasting characteristics of flours produced from some tropical legume seeds. Samples were collected from cowpea (Vigna ungulculata); red kidney beans (Phaseolus vulgaris), and Pigeon pea (Cajanus cajan) and each sample was divided into two portions. A portion was sprouted while the other portion served as the control. The flours from sprouted and non-sprouted seeds were analyzed for the minerals, anti nutritional and pasting properties. The samples were found to differ significantly (p < 0.05) in the minerals, anti nutritional composition and pasting properties of the flours. Sprouting increased the mineral contents of the flours generally the calcium content of non-sprouted red kidney beans (13.8 mg/100 g) increased to 16.1 mg/100 g in the sprouted flour. The haemagglutinin decreased from 40.6 HU/mg in non sprouted red kidney to 6.4 HU/mg in the sprouted. The final viscosity of the non sprouted flours were higher than those of the sprouted, with non sprouted cowpea scoring the highest, 272 RVU, while sprouted red kidney beans had the least, 109.06 RVU, which implies that sprouting caused a reduction in the gel strength and elasticity of the samples. Seed sprouting effectively increased the mineral nutrients and lowered the anti nutrients, but produced steamed paste with poor gel strength.