Effect of processing on flatus producing oligosaccharides in cowpea (Vigna unguiculata) and the tropical African yam bean (Sphenostylis stenocarpa)

The effect of dehulling, soaking and soaking/cooking on sucrose, raffinose and stachyose in mature dry seeds of nine varieties of cowpea (Vigna unguiculata) and one variety of tropical African yam bean (Sphenostylis stenocarpa) were investigated. The results showed a progressive decrease in sucrose, raffinose, and stachyose contents. Soaking for 12 hours and cooking for 30 min eliminated most of the sucrose, raffinose and stachyose. The sugar contents in whole raw cowpea were sucrose 0.73–4.58%, raffinose 0.71–6.86% and stachyose 2.38–3.87%, and for tropical African yam bean sucrose 4.08%, raffinose 1.08% and stachyose 4.14% while the seeds soaked for 12 hours and cooked for 30 min had for cowpea sucrose 0.03–0.81%, raffinose 0.04–0.20% and stachyose 0.12–0.72%, and tropical African yam bean sucrose 0.70%, raffinose 0.40% and stachyose 0.41%.     

Chemical and biological characteristics of a West African weaning food supplemented with compea (Vigna unguiculata)

The effects of cowpea and amino acid supplementation on the protein quality and chemical characteristics of a maize-based West African traditional weaning food were studied. Process optimization for improved nutritive value was also determined. Supplementation of the traditional weaning food with cowpea increased the lysine, tryptophan and threonine content while the sulphur-amino acids decreased with increasing levels of cowpea. Further supplementation of 70:30 maize/cowpea blends with lysine, threonine or methionine did not significantly improve (p>0.05) protein quality in terms of the biological value (BV) and net protein utilization (NPU), although significant increases in the protein scores were noted. However, considerable improvements in the BV and NPU were recorded in blends fortified with either tryptophan alone or a combination of lysine, tryptophan, methionine and threonine. Cooking whole cowpea seeds for 45 min before incorporating in the blend formulation also significantly improved (p<0.05) the protein quality of maize/cowpea blends. The BV and NPU of blends containing 30% pre-cooked cowpea increased from 52 to 76% and 50 to 71% respectively compared to pure maize porridge. The protein content increased from 10 to 14% and the utilizable proteins more than doubled. The weight increase of experimental rats fed with these blends was comparable to that of rats on casein diet. A 30% supplementation of the maize-based weaning food with cowpea therefore greatly enhances the nutritive value especially when the cowpea is pre-cooked for 45 min. Use of chemical scores alone for such blends cannot be a reliable index of blend quality.     

Evaluation of selected food attributes of four advanced lines of ungerminated and germinated Nigerian cowpea (Vigna unguiculata (L.) Walp.)

The chemical composition and functional properties of ungerminated and germinated seeds of four advanced lines of cowpeas (IT81D-699, IT82E-18, IT84S-2246-4 and TVx 3236) were investigated. Ungerminated seeds contained 20.1 to 25.8% crude protein, 2.0 to 2.2% lipid, 115.1 to 210.0 mg phyticacid/100 g and 8.9 to 9.6 mg iron/100 g. The polyphenol contents of the brown- and cream-colored beans were similar (192.0 to 196.0 mg/100 g) but were significantly (p<0.05) higher than the amount (99.8 mg/100 g) found in the white beans. Germination increased the crude protein content, total phosphorus content, nitrogen solubility, fat absorption capacity and foam capacity but decreased ether extract, polyphenol and phytic acid contents, water absorption capacity, bulk density and foam stability of all cowpea lines. Incorporation of up to 0.2 M NaCI improved foam volume. Ungerminated seeds had high water (2.3–3.2 g/g) absorption capacities, while germinated seeds had high fat (3.1–3.6 g/g) absorption capacities. TVx 3236 and IT81D-699 might be selected for combining such characteristics as high crude protein, low phytic acid content and good foaming properties into a single cowpea line through breeding.     

The effects of sun-drying surfaces and packaging materials on the storability of cowpea ( Vigna unguiculata) seed

The effects of sun-drying cowpea seeds for three hours on cement (CS), wood (WS), and corrugated iron sheet (CIS) surfaces and packaging separately in polyethene and jute bags were studied. Moisture-gain, and resistance to insect and mold damage were monitored monthly for six months, while proximate analyses on day zero and at the 6th month were conducted. Results showed that the three-hour sun-drying of cowpea seeds on reflective surfaces (CIS and CS) enhanced the rate of moisture-reabsorption during storage and consequently, the degree of mold and insect damage irrespective of the packaging material employed. Crude fat, fiber and ash contents, unlike protein and moisture contents, remained virtually constant (p 0.05). In this study, the wood surface and polyethene bag were the most preferred treatments to store sun-dried cowpea seeds for about 5.7 months.     

Environmental variables affect the hard-to-cook phenomenon of cowpea (Vigna unguiculata) seed

Changes in moisture content and cooking rate of cowpea (Vigna unguiculata) seeds which were sun-dried for 5 hours on cement, wood, or corrugated iron sheet surfaces and packaged for 6 months in jute or polythene bags were studied. Relationships and effects of interacting variables studied were examined using the contrast analysis technique. From day zero to about 2 months of storage, the sun-dried samples had significantly (p<0.01) lower moisture content and longer cooking times than the corresponding control samples. However, moisture-gain and cooking time increased progressively throughout the storage period for all samples studied. The relationship between these two variables, tested at p=0.01 using contrast analysis technique, was dependent on the choice of packaging material.     

Supplementation of irradiated and non-irradiated cowpea bean (Vigna unguiculata L. Walp) protein with cereal proteins

The quality of the cowpea bean protein was improved through supplementations with flours from beans exposed to microwave oven treated with cereal proteins such as wheat, rice, corn, and sorghum. Biological assays results with these blends showed that the casein exceeded the other diets concerning digestibility only; however, in parameters such as biological value, net protein utilization (NPU), protein efficiency ratio (PER) and nutritional efficiency ratio (NER), no significant differences occurred. Among all elaborated blends, the one with irradiated beans submitted to microwave oven for 30 minutes (65%) + rice (35%) presented the best results. The soup elaborated with the best supplemented blend was satisfactory concerning color, odor, flavor and texture.     

Effect of processing method on the quality of cowpea (Vigna unguiculata) flour for akara preparation

An indigenous food mixture containing rice flour, milk coprecipitate, sprouted green gram paste and tomato pulp (2: 1: 1: 1 w/w) was developed and called a RCGT food mixture. It was autoclaved (1.5 kg/cm², 15min, 121 °C), cooled and fermented with 2% liquid culture (containing 10⁶ cells/ml broth). Two types of fermentations were carried out i.e. one step single culture fermentation [L. casei or L. plantarum (37 °C, 24 hr.)] and sequential culture fermentation [S. boulardii (25 °C, 24 hr.) +L. casei (37 °C, 24 hr.)]; [S. boulardii (25 °C, 24 hr.) + L. plantarum (37 °C, 24 hr.)]. All fermentations drastically reduced the contents of phytic acid, polyphenols and trypsin inhibitor activity while significantly improving the in vitro digestibilities of starch and protein. Sequential culture fermentations brought about further changes compared to one step single culture fermentation.     

Content of antinutrients and in vitro protein digestibility of the African yambean,pigeon and cowpea

The protein, trypsin inhibitor (TI), tannin, phytate, phytic acid phosphorus and in vitro protein digestibility (IVPD) of cultivars of the African yambean (Sphenostylis stenocarpa) — AYB, pigeon pea (Cajanus cajan) — PP and cowpea (Vigna unguiculata) — CP were determined. The protein content of CP (24–28.0%) was higher than those of PP (21–22.5%) and AYB (21–22.5%). The cream and speckled AYB contained more TI (30.9 and 25.3 mg/g) than PP (7.5–14.1 mg/g) and CP (9.8–20.5 mg/g). Apart from the white CP cultivar, they contained more tannin (1.24–1.42 mg/g) than PP (0.14–0.97 mg/g) and AYB (0.71–1.17 mg/g). Phytate was lowest in the AYB (6.30–7.49 mg/g) than PP (8.31–11.31 mg/g) and CP (8.40–9.92 mg/g). Phytic acid contributed 67–74% of the phosphorous in the AYB, 66–75% in PP and 54–59% in CP. The IVPD of the AYB (73.3±0.7%) was significantly lower (p<0.05) than those of PP (76.34±0.2%) and CP (77.8±0.4%). There was a significant negative correlation between TI and IVPD (r=–0.63,p<0.05). There was no significant correlation between IVPD and phytate and tannin contents. There was a positive correlation between protein content and IVPD (r=0.69**) for the legumes under study. These legumes may pose no serious problems to populations consuming them especially when heat treatment is applied before consumption.     

Selected nutritional components and sensory attributes of cowpea (Vigna unguiculata [L.] Walp) leaves

Reports on the nutritional composition of cowpea leaves have been limited to a small number of lines and the palatability characteristics of leaves apparently have not been studied. This study was therefore undertaken on cowpea leaves to determine the nutrient composition of fifteen varieties and the sensory attributes of ten varieties grown in Ghana. Nutritional components studied were moisture, protein, phosphorus and ascorbic acid. The sensory attributes included leaf size, taste and overall acceptability. There were significant (p > 0.05) differences among varieties in all nutrient components (fresh and dry weight basis), leaf size and overall acceptability. The nutrient composition values, on a dry weight basis, ranged from 9.4 to 13.0% for moisture, 303.8 to 468.9 mg/100 g for phosphorus, 33.5 to 148.0 mg/100 g for ascorbic acid, and 27.1 to 34.7% for protein. Differences in the sensory scores of leaves for taste were not significant (p < 0.05). Overall acceptability positively correlated with leaf size. Moisture content was negatively correlated with overall acceptability, phosphorus and ascorbic acid. Results can be exploited in a breeding program to develop nutritionally superior and acceptable cowpea varieties which can be used for harvesting of both leaves and seeds.     

Nutritional quality of germinated cowpea flour (Vigna unguiculata) and its application in home prepared powdered weaning foods

Amino acid profiles, protein digestibility corrected aminoacid scores (PDCAAS), chemical scores, essential amino acid indexes, andcalculated biological values of control-cowpea flour (CCF), germinated cowpeaflour (GCF) prepared from cowpeas germinated at 25 ^°C for either24 h or 48 h and weaning foods prepared from cowpea flours weredetermined. Locally available rice, cowpea flour, banana-pumpkin slurry,and skim milk powder and sucrose in the ratio 35:35:15:15:5 were used to formulateweaning food containing not less than 15% protein. The ingredients werecooked into a slurry and oven-dried to produce flakes. The nutritional andsensory qualities of the weaning products were evaluated. Germination hadlittle effect on the amino acid profile of cowpeas. In vitro proteinquality and starch digestibility were improved in germinated cowpea flour. The PDCAAS of 24 h germinated cowpea flour (GCF) weaning food washigher (55.49%) than CCF-weaning food (46.74%). Vitamin A activityin 24 h GCF weaning food was higher than in CCF-weaning food. Invitro starch digestibilities of 24 h GCF and 48 h GCF-weaning foods werehigher than that of CCF weaning food. The 24 h GCF-weaning food which hada higher overall acceptability score by sensory panelist than 48 h GCFand CCF-weaning food is recommended for household consumption.     

Effect of thermal treatments on the chemical and biological value of irradiated and non-irradiated cowpea bean (Vigna unguiculata L. Walp) flour

Chemical and nutritional characteristics of irradiated and nonirradiated cowpea bean at 0.2 kGy submitted to several thermal treatments were studied. The cowpea bean flours irradiated at 0.2 kGy were superior to those non-irradiated concerning digestibility and the flours submitted to microwave oven were superior to those cooked under low pressure, autoclaved or even raw from the nutritional point of view. As to the presence of anti-nutritional factors, the results showed that the variety of cowpea bean under research presented neither trypsin inhibitor nor haemagglutinin activity, however, regarding tannin, a 0.006% content was found and considered negligible.     

Effects of infestation on the nutrient content and physiocochemical properties of two cowpea ( Vigna unguiculata) varieties

Two cowpea varieties (Ife-brown and Kano-white varieties) were used for the study. The effects of insect infestation on the chemical composition and physicochemical properties of these cowpea seeds were studied. The proximate composition, mineral content, total starch, total soluble sugars, bulk density, fat and water absorption capacities, viscosity, gelation capacity and emulsion properties of infested cowpea varieties were compared with those of uninfested cowpeas. Effects of infestation on nitrogen solubulity and on the protein fractions were also determined. lnfestation depleted the protein, starch and soluble sugar contents of cowpeas. Oil and water absorption capacities were increased while emulsification, foam and viscosity properties were reduced. The nitrogen solubility pattern was altered. Uninfested Kano-white cowpeas (UKW) possessed better foam properties than uninfested Ife-brown cowpeas (UFB). On the other hand, UFB had better emulsification properties than UKW.     

Effects of heat on the removal of polyphenols and in vitro protein digestibility of cowpea (Vigna unguiculata (L.) Walp.)

Simple wet heat treatments like simple boiling (atmospheric pressure, 100 °C) and pressurized boiling (higher than 100 °C) reduced the polyphenol content of mature dark red seeds of cowpea (Vigna unguiculata (L.) Walp.) cultivar UPL Cp 3 by 61 to 80% and improved in vitro protein digestibility (IVPD) by 6 to 26%. Pressurized steaming (higher than 100 °C) removed 48 to 83% of the polyphenols but increased IVPD by only 1.1 to 4.2%. Dry heat as exemplified by roasting and microwave treatment inactivated 58 to 71% of the tannins but increased IVPD by only 1%. All the heat treatments were effective in removing/inactivating polyphenols though different responses were observed with the resulting in vitro protein digestibilities.     

Amino acid composition protein quality and water-soluble vitamin content of germinated cowpeas (Vigna unguiculata)

Amino acid composition, protein digestibility, calculated protein efficiency ratio (C-PER and DC-PER), chemical scores and water-soluble vitamin content of cowpea seeds germinated at 25°C or 30°C for 24h were determined. Also, the effect of processing steps (heated-air drying, decortication and cooking) on these parameters were examined. Germination had little effect on amino acid profile of cowpeas. In vitro protein digestibility was not improved significantly by germination nor by decortication but was improved by cooking. C-PER and DC-PER ranged from 1.95 to 2.21 and from 1.63 to 1.82, respectively. DC-PER compared well withreported rat PER of cowpea products and seemed more sensitive than C-PER. Based on whole egg values, chemical scores ranged from 37.7 to 45.8% (mean±SD; 42.2±2.4%). Germination increased the contents of niacin, thiamin and riboflavin significantly. Decortication resulted in up to 30% loss in niacin while thiamin content was reduced 41% by cooking.     

Effects of cooking,germination and fermentation on the chemical composition of Nigerian Cowpea (Vigna unguiculata)

The effects of cooking, germination, and fermentation on the chemical composition of cowpea were studied. There were noticeable trends in the protein, carbohydrate and crude fiber as a result of the different treatments. Both the germinated and fermented samples contained more ether extractable lipids than the raw and cooked samples. Untreated raw cowpea contained 5.9 mg/g phytic acid, 1.66 mg/g phytate phosphorus, 3.3 mg/g total phosphorus, 56.8 mg/g total sugar, and no reducing sugar. Cooking the dry beans at 100°C for 1 1/2 hours had little effect on the phytic acid and phytate phosphorus. There were, however, significant decreases in total phosphorus and sugars of the cooked beans. After germination for 24 hours, 48 hours and 72 hours respectively, there was a significant decrease in phytic acid and total sugar and increase in total phosphorus and reducing sugar. Similar results were also obtained when the dry beans was fermented for 24 hours, 48 hours and 72 hours respectively.     

Effect of reconstitution and Na2Co3 on tannin content and in vitro protein digestibility of faba bean cultivars

Two faba bean cultivars (317/99/81 and Giaz/402) obtained from Shambat Research Station in Northern Sudan, were used for this study. Investigation showed that the tannin contents of untreated seeds were 0.077% and 0.067% for cultivars 317/99/81 and Giza/402. In vitro protein digestibility values were 80.68% and 81.48% for the two cultivars, respectively. The extractable tannin content of the faba bean cultivars was markedly reduced by imbibing water or Na₂CO₃ solution into whole seeds and incubating them at 30°C for 1, 3, 6, 12 or 24 hours, or at 100°C for 5, 10 or 20 minutes. The extent of reduction depended on time, temperature, and Na₂CO₃ concentration; the percent tannin extracted and percent in vitro protein digestibility increased with time or Na₂CO₃ concentration, while application of high temperature reduced the time.     

The effects of sun-drying surfaces and packaging materials on the storability of cowpea (Vigna unguiculata) seed.

The effects of sun-drying cowpea seeds for three hours on cement (CS), wood (WS), and corrugated iron sheet (CIS) surfaces and packaging separately in polyethene and jute bags were studied. Moisture-gain, and resistance to insect and mold damage were monitored monthly for six months, while proximate analyses on day zero and at the 6th month were conducted. Results showed that the three-hour sun-drying of cowpea seeds on reflective surfaces (CIS and CS) enhanced the rate of moisture-reabsorption during storage and consequently, the degree of mold and insect damage irrespective of the packaging material employed. Crude fat, fiber and ash contents, unlike protein and moisture contents, remained virtually constant (p < or = 0.05). In this study, the wood surface and polyethene bag were the most preferred treatments to store sun-dried cowpea seeds for about 5.7 months.     

Use of two varieties of hard-to-cook beans (Phaseolus vulgaris) and cowpeas (Vigna unguiculata) in the processing of koki (a steamed legume product)

Koki is a nutritious cowpea-based food product usually processed by steam cooking whipped cowpea (Vigna unguiculata) paste mixed with spices and palm oil. A study was carried out to investigate the effect of the partial replacement of cowpeas (CP) with hard-to-cook (HTC) beans on the chemical, nutritional and sensory characteristics of koki. Towards this objective, two varieties of beans – Phaseolus vulgaris (red kidney beans – RKB and mottled brown beans – MBB), each with the HTC defect, were separately incorporated into cowpea paste in the following Bean:CP ratios 0:100, 20:80, 30:70, 40:60, 50:50, 60:40 and processed into koki. Incorporation of dry HTC beans into cowpeas in the making of koki affected the bulking properties of the uncooked paste, the nutrient composition, essential amino acid content, antinutritional factors, digestibility as well as the sensory attributes of cooked koki. Sensory tests showed that a highly acceptable, nutritious and digestible koki can be processed from cowpeas partially replaced with dry HTC bean paste up to levels of about 40–50% depending on the variety of dry bean used.     

子叶损伤对豇豆生长发育的影响

分别剪去豇豆幼苗1/2片子叶、1片子叶、2×1/2片子叶、1＋1/2片子叶、2片子叶,以不剪子叶为对照,研究子叶损伤对豇豆生长发育的影响。结果显示：处理后,植株生育期推迟,真叶变短,始花节位数下降,茎变细,豆荚变短增粗,产量降低10%以上,无论春季还是秋季,子叶损失率与产量都有极显著的直线回归关系。     

Effect of suppressing the synthesis of different kafirin sub-classes on grain endosperm texture, protein body structure and protein nutritional quality in improved sorghum lines

To improve sorghum grain protein nutritional quality, improved sorghum lines were transformed to suppress the synthesis of different kafirin sub-classes, or backcrossed into transgenic lines with improved protein quality. Co-suppression of the alpha-, gamma- and delta-kafirin sub-classes and removal of the tannin trait resulted in transgenic sorghum lines with high cooked protein digestibility (±80%), improved Amino Acid Score (0.8) and Protein Digestibility Corrected Amino Acid Score (0.7) compared to the non-transgenic null controls (±50%, 0.4 and 0.2, respectively). These high protein quality lines had a floury endosperm. They also had modified protein body structure, where the protein bodies were irregular shaped with few to numerous invaginations and were less densely packed, with a dense protein matrix visible around the protein bodies. When fewer sub-classes were suppressed, i.e. gamma 1 and delta 2, the endosperm was corneous with normal protein body structure but the improvement in cooked protein digestibility appeared to be less. Apparently, co-suppression of several kafirin sub-classes is required to obtain high protein nutritional quality sorghum lines, but this seems to result in floury-type grain endosperm texture.