Genetic and environmental variability in starch,fatty acids and mineral nutrients composition in cowpea (Vigna unguiculata (L) Walp)

Fifteen cowpea cultivars grown in three locations (Kano (12°00′N 8°31′E), Mokwa (9°17′N 5°04′E) and Ago-Iwoye (6°58′N 4°00′)) between 1993 and 1994 were analysed for genotype, environmental and genotype×environment variability for starch (g kg⁻¹), fatty acids (% of total oil) and mineral nutrients (g kg⁻¹) composition. There were significant environmental as well as genetic effects on these nutritional qualities. The environmental effect accounted largely for the variability observed in starch (60%), palmitic acid (80%), arachidic acid (100%), potassium (100%), phosphorus (81%) and manganese (86%), while the genotypic effect accounted largely for the variability observed in linoleic acid (50%), linolenic acid (50%) and copper (68%) contents. Correlation coefficient (pooled data) from the three locations indicated that starch was positively correlated to palmitic acid (r = 0·21, 0·01< P < 0·05), potassium (r = 0·80, P < 0·001) and phosphorus (r = 0·65, P < 0·001), but negatively correlated to oleic (r = −0·23, 0·01< P < 0·05), linoleic (r = −0·67, P < 0·001) and linolenic acid (r = −0·74, P < 0·001) contents. Starch showed a strong positive correlation with magnesium content (r = 0·75) and a strong negative correlation with copper (r = −0·73) and iron (r = −0·62) at the genetic level. This research established the degree of variability for these characters in cowpea. © 1998 Society of Chemical Industry.     

Genetic and Environmental Variation for Seed Yield,Protein, Lipid and Amino Acid Composition in Cowpea (Vigna unguiculata (L) Walp)

The genetic and environmental variability for seed yield (kg ha^-1), protein content (g kg^-1 DM), lipid content (mg g^-1 DM) and essential amino acid composition (g per 16 gN) of cowpea seeds using 15 cultivars grown in three locations (Kano (12°00′ N 8°31′ E), Mokwa (9°17′ N 5°04′ E) and Ago-Iwoye (6°58′ N 4°00′ E)) that differ markedly in climate was studied. The environmental effect accounted largely for the variability observed in yield (93%), protein (71%), lipid (100%), threonine (96%), cystine (80%) and arginine (81%) while the genotypic effect accounted largely for the variability observed in methionine (56%) and lysine (51%) contents. Correlation coefficients (pooled data) from the three locations indicated that yield was negatively correlated to protein content (r=-0·87, P<0·001) and positively correlated to lipid content (r=0·73, P<0·001). Protein content was negatively correlated to lipid content (r=-0·67, P<0·001) and positively correlated to threonine (r=0·66, P<0·01), cystine (r=0·69, P<0·001) and methionine (r=0·88, P<0·001) contents. Similarly, yield was positively correlated to threonine (r=0·22, 0·01<P<0·05), cystine (r=0·38, 0·001<P<0·01) and methionine (r=0·67, 0·001<P<0·01). Yield showed a strong negative correlation with protein content (r=-0·81) and a strong positive correlation with lipid content (r=0·97) at the environmental level. Cystine, methionine and to some extent, threonine were the limiting amino acids in the three environments. This research established the degree of variability for these characters in cowpea and indicated that concurrent selection for yield, lipid content, threonine and sulphur amino acids compositions is feasible. © 1997 SCI.     

Inheritance of protein content in seeds of selected crosses of cowpea (Vigna unguiculata)

The inheritance pattern of protein content in seeds of two crosses of cowpea (Vigna unguiculata (L) Walp) was studied. It was observed that, in both crosses, inheritance of the character involved both additive and non-additive gene effects. Heritability in the broad sense was 0·70–0·78. A significant effect of pollen source was detected in one of the two crosses. In both crosses, comparison of seed protein content of reciprocal segregating generations indicated the influence of cytoplasmic factors.     

Proximate composition,amino acid content and haemagglutinating and trypsin‐inhibiting activities of some Brazilian Vigna unguiculata (L) Walp cultivars

Seeds of Brazilian Vigna unguiculata (L) Walp cultivars (EPACE 10, EPACE 11, Pitiuba, TVu 1888, IPA 206 and Olho de Ovelha) were analysed to establish their proximate composition, amino acid content and presence of antinutritional and/or toxic factors. The seed protein, carbohydrate and oil contents ranged from 195 to 261 g kg⁻¹ dry matter, from 678 to 761 g kg⁻¹ dry matter and from 12 to 36 g kg⁻¹ dry matter respectively. EPACE 10, EPACE 11, Pitiuba, TVu 1888, IPA 206 and Olho de Ovelha cultivars are rich in glutamin/glutamic acid, asparagin/aspartic acid and phenylalanine + tyrosine. The essential amino acid profile compared with the FAO/WHO/UNU scoring pattern requirements for different age groups showed that these seeds have methionine + cysteine as the first limiting amino acid for 2–5‐year‐old children. However, only Pitiuba, IPA 206 and Olho de Ovelha are deficient in methionine + cysteine for 10–12‐year‐old children. The contents of threonine, valine, isoleucine, leucine and methionine + cysteine of all cultivars were lower than those of hen egg. Haemagglutinating activity measured against rabbit erythrocytes was found to be present in the six cultivars, but only after the red cells were treated with proteolytic enzymes. All cultivars displayed protease inhibitor activity which varied from about 12.0 to 30.6 g trypsin inhibited per kg flour. Urease and toxic activities were not detected in any of the studied cultivars. © 2000 Society of Chemical Industry     

Genotype × environment influence on cowpea (Vigna unguiculata (L) walp) antinutritional factors: 1 – trypsin inhibitors,tannins, phytic acid and haemagglutinin

The relative influence of genotype, environment and genotype×environment effects on four antinutritional factors (g kg⁻¹) of importance in cowpea were studied using 15 local and improved cowpea genotypes grown in 12 environments, comprising three locations over four seasons per location. The locations Ago‐Iwoye (6°58′N4°00′E), Mokwa (9°17′N5°04E) and Kano (12°00′N8°31′E) were representatives of the major agroecological zones where cowpeas are produced. Genotypes effects were strongest in controlling trypsin inhibitor content, while the environment was the major source of variation for tannins, haemagglutinin and phytic acid contents. Thus, the variability in the levels of these antinutritional factors in cowpea seeds depends largely on the environment where they are grown. This implies that a cowpea genotype grown and consumed safely in an environment can be poisonous when grown and consumed in another environment. Genotype×environment effects were significant for tannins, haemagglutinins and trypsin inhibitor contents. Correlation coefficients (pooled data) from the three locations indicated that trypsin inhibitor was positively correlated to phytic acid (r=0.59, 0.001<P<0.05) and haemagglutinins (r=0.64, 0.001<P<0.05) but negatively correlated to tannin contents ( r=−0.79, 0.001<P<0.05). © 1999 Society of Chemical Industry     

Evaluation of cooking time and quality of seven diverse cowpea (Vigna unguiculata (L.) Walp.) varieties

Seven cowpea ( Vigna unguiculata (L.) Walp.) varieties, which were part of a larger collection evaluated in agronomic field trials in Botswana, were selected for characterization of cooking time and quality. Newly harvested seed was kept in the open air for 2 weeks, then stored at 4°C and 40% relative humidity for 3 months. Duplicate samples were tested for cooking time with and without 12-h prior soaking. Varieties showed differences ( P < 0.01) in cooking time and response to soaking, although the overall effect of soaking was insignificant. Cooking times ranged from 29 to 64 min without soaking and 36 to 56 min after soaking, with small-seeded varieties having the longer cooking times. The seed coat of some varieties readily became soft, but others remained tough or split before finally softening.     

Effect of milling method on selected physical and functional properties of cowpea (Vigna unguiculata) paste

Particle size distribution (PSD) of cowpea meal is an important determinant of paste functionality and end product quality. Samples from various mills and screen sizes were used to determine PSD, water‐holding capacity (WHC) and swelling capacity (SWC). Hammer mill (1.73 mm screen) meal had a geometric mean diameter (d_gw) of 221 microns, whereas PM‐360 [plate mill with one complete turn (360°) of clearance] meal had a d_gw of 1559 microns. All other milling processes resulted in meal with an intermediate particle size. To reduce the particle size of cowpea pastes, cowpea meals were hydrated to pre‐determined moisture contents, held for 15 min, and then blended in a blender before whipping. Blending increased the WHC and SWC of all samples.     

Physico-chemical properties of the flours and starches of two cowpea varieties (Vigna unguiculata (L.) Walp)

The physical and chemical properties of the starches and flours of whole grain and decorticated two cowpea varieties (Vigna unguiculata (L.) Walp) were investigated. The two cowpea varieties were: C-152-White, having big grain and S-1552-White, having small grain with black eye. Results showed that starch yields were 19.2 and 16.4 g/100 g grain for C-152 and S-1552, respectively. Statistical analysis shows that the total amylose contents of the starch of the two cowpea varieties were significantly higher (P ≤ 0.05) than that of the whole grain and decorticated flours. The swelling power of C-152 starch was significantly higher than that of S-1552 starch. The water-binding capacity (WBC) for S-1552 starch was higher than for C-152 starch. The results of pasting profile of both the flour and the starch showed that the two cowpea varieties possess different properties in relation to gelatinization temperature(GT), peak viscosity (PV), hot paste viscosity (HPV), cold paste viscosity (CPV), break down (BD), set back (SB), total set back (SBt) and relative breakdown (BDr). The information generated in this study on the properties of the starch could provide guidance on possible industrial uses of starches of these two varieties.Industrial relevanceThis work showed the peculiar characteristics (solubility, water-binding capacity, amylose content, carbohydrate composition, granules characteristics and behaviour in Brabender viscoamlograph) of pure cowpea starch. The results that we obtained could be very valuable in decision making for industries that want to take advantage of cowpea starch as alternative or supplement to cereal/tuber starch. Cowpea starch could be useful in the manufacture of thickeners, gelling agent, extenders and texture modifiers in food formulation.     

Effect of water hardness on cooking characteristics of cowpea (Vigna unguiculata L. Walp) seeds

Cowpeas were cooked in water made hard (or soft) by the separate addition of similar concentrations of certain salts (CaCl₂, MgCl₂, or NaHCO₃). The beans were also cooked in hard tap water and in double distilled water before and after soaking in water. Hard water caused a significant decrease in softness, led to reduced water absorption, and also decreased solids loss in the cooked product, but it increased the cooking time and discolouration of the beans. Hard water also gave rise to a significant ( P <0.05) increase in mineral content, but it had less effect on the proximate composition of the cooked products.     

Stability of quinoa flour proteins (Chenopodium quinoa Willd.) during storage

The amino acid composition and the physicochemical and functional properties of quinoa flour proteins (QFP) were evaluated during storage (at 20, 30 and 40 °C). Quinoa flour showed a protein content of 14.2 ± 0.1 g 100 g⁻¹ and high levels of essential amino acids as lysine. SDS–PAGE of the QFP presented ten major band, and native-PAGE of the QFP showed similar banding; there was a little variation due to time-temperature. TCA-protein solubility variation (%) was small and the values of water activity were low, a non-significant endogenous hydrolysis was observed. Differential scanning calorimetry flour analysis allowed determining two endotherms, starch and protein. Important structural changes of protein soluble fractions were not detected by UV and fluorescence spectroscopy due to temperature and time of storage. It was found during storage time loss of protein solubility and water absorption. These changes could be to influence in the manufacture of quinoa flour based products. For avoid changes in these functional properties (solubility and water holding capacity), quinoa flour can be stored at ambient temperature (between 20 and 30 °C) and packed in double kraft paper bags (2 months).     

Comparative studies of some properties of undehulled, mechanically dehulled and manually dehulled cowpea (Vigna unguiculata Walp. L.) flours

A comparative evaluation was made of some physico‐chemical and rheological characteristics of undehulled, manually dehulled and mechanically dehulled cowpea (Vigna unguiculata Walp. L.) flours from brown and white varieties of the legume. The flours were used to prepare steamed bean paste, ‘Moinmoin’, which was analysed for some sensory parameters. Dehulling and dehulling methods had no appreciable influence on the physical characteristics and proximate composition of the flours, except ash content, which was slightly higher in undehulled flour samples. Amylograph pasting characteristics of the flours showed varying trends because of dehulling method and/or presence of seed coats. ‘Moinmoin’ samples prepared from the flours received similar ratings for all sensory attributes, with no significant differences (P < 0.01 and P < 0.05), except for the low‐rated (poorer) colour of the undehulled brown product.     

Changes in the biochemical and functional properties of the extruded hard‐to‐cook cowpea (Vigna unguiculata L. Walp)

Changes in the biochemical and functional properties of the hard‐to‐cook cowpea bean after treatment by the extrusion process are reported. The extrusion was carried out at 150 °C, with a compression ratio screw of 3:1, a 5‐mm die, and a screw speed of 150 r.p.m. The extrusion caused the complete inactivation of the α‐amylase and lectin and it also reduced the trypsin inhibitor activity (38.2%) and phytic acid content (33.2%). The functional properties were also modified by the process, an increase of 2.5 times in the water absorption index and 3.1% in the water solubility were observed. The digestibility of the hard‐to‐cook flour of the cowpea bean was improved after the extrusion, with a 55.9% increase in protein digestibility and a 5.9% increase in starch digestibility.     

Gamma irradiation of cowpea (Vigna unguiculata L. Walp) seeds: effect on colour,cooking quality and pasting characteristics

Cowpea seeds were treated to various gamma irradiation doses, and their colour, cooking quality and pasting properties studied. Irradiation at 50 kGy resulted in significant browning (indicated by decreases in L colour value) of cowpea seeds. At 2 and 10 (but not at 50) kGy, irradiation led to significant reduction in cooking time of cowpea seeds possibly through irradiation‐induced degradation of starch and pectic substances (indicated by decreases in peak and final viscosities) leading possibly to enhanced heat and mass transfer within the seed cotyledon and cell wall, respectively. At 50 kGy, the cooking time of cowpea seeds was prolonged significantly owing possibly to extensive polymer cross‐linking occurring within the seeds at this high dose. Splitting of cowpea cotyledons during cooking decreased significantly at 50 kGy, but was unaffected at 2 and 10 kGy. Irradiation resulted in significant leaching of nutrients from cowpea seeds during cooking in a dose‐dependent manner.     

Biological activity of Cassia occidentalis L. against Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

In developing countries, traditional control methods are commonly used against stored-product insects and mites. In Senegal, the leaves of Cassia occidentalis L. (Caesalpiniaceae) are used to protect cowpea seeds (Vigna unguiculata L. (Walpers)) against Callosobruchus maculatus (Coleoptera: Bruchidae). The biological activity of the leaves, the seeds and oil of C. occidentalis was evaluated in controlled conditions (28 ± 2°C, 45 ± 5% r.h.) against C. maculatus. At the rate of 10% (w/w), both fresh and dry leaves as well as whole and ground seeds had no contact toxicity on the cowpea beetle. In contrast, seed oil induced an increase in mortality of C. maculatus eggs and first larval instar at the concentration of 10 ml/kg cowpea. The basis of the ovicidal and larvicidal activities are discussed in this paper. Several trials using pure compounds have highlighted that several fatty acids (linoleic, oleic and stearic) are responsible for C. occidentalis toxicity. C. occidentalis seed oil did not reduce the oviposition of C. maculatus at 10 ml/kg seed.     

Walnuts (Juglans regia L): proximate composition,protein solubility,protein amino acid composition and protein in vitro digestibility

Walnuts contained 16.66% protein and 66.90% lipids on a dry weight basis. Non‐protein nitrogen values ranged from 6.24 to 8.45% of the total nitrogen when the trichloroacetic acid concentration was varied within the range 0.25–1.0 M . Albumin, globulin, prolamin and glutelin respectively accounted for 6.81, 17.57, 5.33 and 70.11% of the total walnut proteins. Walnut proteins were minimally soluble at pH 4.0. The majority of total walnut protein polypeptides had estimated molecular weights in the range 12 000–67 000. The Stokes radius of the major protein in walnuts (glutelin fraction) was 66.44 ± 1.39 Å. Lysine was the first limiting essential amino acid in total walnut proteins as well as in the globulin and glutelin fractions. Leucine and methionine plus cysteine were the second limiting essential amino acids respectively for the prolamin and albumin fractions. Hydrophobic and acidic amino acids dominated the amino acid composition in all protein fractions. Native and heat‐denatured walnut glutelins were easily hydrolysed by trypsin, chymotrypsin and pepsin in vitro. © 2000 Society of Chemical Industry     

Relationship of hydrophobicity and solubility with some functional properties of cowpea (Vigna unguiculata) protein isolate

The relationship of hydrophobicity and solubility with some functional properties of cowpea protein isolate was determined. Cowpea protein isolate was prepared by alkali extraction followed by precipitation at pH 4.5. The precipitated proteins were then neutralized to pH 7. Heating of the protein isolate to 100°C for 10 min followed by cooling to room temperature resulted in a significant (P ≦ 0.05) decrease in aromatic hydrophobicity (ARH) when compared to the native protein isolate. The inclusion of sodium dodecyl sulfate (SDS) during heating gave a significant (P ≦ 0-05) 1.7-fold increase while inclusion of mercaptoethanol (ME) gave a significant (P ≦ 0.05) 2.5-fold increase in ARH of the cooled protein solution. Protein solubility (PS), foam expansion (FE) and emulsification activity index (EAI) of the isolate generally increased significantly (P ≦ 0.05) upon heating or treatment with urea or SDS or a combination of SDS and ME. Backward stepwise multiple regression was used to obtain equations for predicting emulsifying and foaming properties of the protein isolate from solubility and hydrophobicity parameters. PS, ARH and aliphatic hydrophobicity (ALH) were important in predicting foam stability and emulsion stability, while PS and ALH were important for predicting FE. ALH alone was important for predicting EAI.     

Lipid and protein stability of partially defatted walnut flour (Juglans regia L.) during storage

Partially defatted walnut flour (WF) was stored (25 °C, 800 Lux) for an 8‐month period and evaluated monthly in some protein properties and oil oxidative parameters. Transparent plastic‐laminated (WFPL) and plastic‐laminated, aluminium‐coated (WFAC) packages were used. During the first 3 months, samples were more susceptible to endogenous hydrolysis; an increase in soluble peptide concentration was determined for both WFAC and WFPL. Minor changes between WFAC and WFPL were observed in protein electrophoretic patterns along storage period, but no differences were determined in total protein solubility. However, a progressive reduction in water‐holding capacity (47% from time 0 to month 8) was observed for WFPL. A major effect of packaging material was found on lipid‐quality parameters. Packaging materials’ barrier to light effectively protect WF against polyunsaturated FA degradation and oil oxidation. Lipids from WF stored in plastic‐laminated packages showed decreasing double‐bond index values (from 1.71 at initial time, to 1.45 after 6 months of storage) and increasing oxidation rates along storage test. Aluminium‐coated packages can be used to keep quality of WF for 8 months at room temperature.     

Chemical composition,in vitro starch digestibility and amino acid analysis of a underexplored kidney bean (Phaseolus vulgaris. L.) grown in Chongqing,China

Chemical composition, mineral analysis, in vitro starch digestibility, and amino acid analysis of a kidney bean (Phaseolus vulgaris. L.), grown in Chongqing, China, were carried out in 2011. The results showed that the bean flour contained low reducing sugar (0.79%) and fat (2.72%), but high protein (24.8%) and starch (44.84%). Mineral analysis indicated high Mg and Ca contents with low Na/K ratio (0.04). The proportions of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) were 39.64%, 41.46% and 18.90% respectively. And the variation in their proportions, along with prolonged heating time, showed increase in RDS, and decrease in SDS and RS, but the SDS + RS amount can still account for major parts (51.63%) of the total starch after a 90‐min pre‐cooking. Comparing the amino acid contents of the bean sample with recommended profile FAO/WHO/UNU (1985), the results fulfil the standard except threonine and lysine, whose contents are slightly lower than the requirements (0.93 and 0.85).     

Post-mortem changes in viscera of cuttlefish Sepia officinalis L. during storage at two different temperatures

We observed the post-mortem changes in viscera of cuttlefish Sepia officinalis in order to apply the data to autolysate production. Cuttlefish viscera were stored at 4 or 25 °C and sampled regularly over 4 months. Our results showed that total acid proteases and cathepsins were rapidly released to the extracellular medium due to the breakdown of lysosomes. Total alkaline protease activity increased 2 h after death due to the breakdown of zymogene vesicles. The same patterns were found with trypsin, chymotrypsin and α-amylase activities. After 10 days of incubation, no endogenous enzymatic activity was found. After 50 days of storage, the TCA soluble protein levels decreased rapidly to approximately 30% due to protein degradation and aggregation. After 10 days, the pH of viscera stored at 25 °C was alkaline, whereas in the viscera stored at 4 °C the pH increased more slowly. As significant reduction in the protein molecular weight due to autolysis, was also observed.