Prebiotic effect of resistant starch from Vigna unguiculata (L.) Walp. (cowpea) using an in vitro simulated digestion model

There has been growing interest in the use of resistant starch (RS) as a prebiotic for physiological benefits and to reduce the risk of chronic diseases. In this study, RS was isolated from samples of five cowpea cultivars (DT129-4, TVU 11424, PAN 311, Fahari and Bechuana White) seeds to determine their potential prebiotic effects, and proximate and mineral composition. Results obtained showed samples of five cowpea cultivars to be high in protein (18.0–28.7%) and carbohydrates (54.9–66.0%) and low in fat (0.6–3.7%). The RS from cowpea samples ranged between 9.3 and 12.1% with cultivar DT129-4 having the highest amount. Fermentation of RS using mixed and pure cultures was done, and bacterial growth was monitored over a 24-h period. Resistant starch isolated from all cowpea samples fulfilled the criteria to be classified as a prebiotic which have a wide range of beneficial effects on the host, with cultivar DT129-4 showing the most prebiotic potential amongst cowpea samples tested.     

Nutritional,physicochemical, and textural properties of gluten-free extruded snacks containing cowpea and whey protein concentrate

Ready-to-eat extruded snacks with high protein and fibre were developed from a composite flour comprising rice flour, cowpea flour and whey protein concentrate (WPC). Nutritional, physicochemical, and textural properties of extrudates were evaluated, at five ratios of cowpea: WPC (10:0, 15:05, 20:10, 25:15, 30:20); rice flour was used as a control. The protein and fibre content in the extrudates significantly increased (P ≤ 0.05) with cowpea (10%–30%) and WPC (5%–20%) incorporation compared to the control. The extrudates with higher levels of cowpea and WPC showed a significant increase in bulk density and hardness. A slight decrease of 12% was observed in the expansion of 15% cowpea and 5% WPC fortified extrudates compared to the control. The number of peaks during compression increased with incorporations of cowpea and WPC. All cowpea and WPC containing snacks were darker than the control. Significant correlations were found between the protein, fibre, colour values and textural properties. The essential and non-essential amino acid profiles increased in the extrudates, proportionally to the cowpea and WPC fortification.     

Technological functionality of composite flours from sorghum,tapioca and cowpea

Composite flours from accessible raw materials may interest developing countries, cutting wheat import costs, bolstering domestic agriculture and boosting nutrition. Technological functionality (WHC and OHC, pasting, swelling and thermal properties) of composite tapioca, sprouted sorghum, cowpea and wheat flours (at 50%, 33% and 25% (w/w) flour basis) was evaluated. PCA revealed that, in a 50% w/w blend, sprouted sorghum and tapioca were technologically similar to wheat, and thus of interest when gluten's viscoelastic properties are not required (e.g. flatbread). Since cowpea flour can enhance nutrients, a flour from sprouted sorghum, tapioca and cowpea is preferable nutritionally and technologically, and potentially sustainable, its raw materials being available locally. Furthermore, PCA showed that composites of sprouted sorghum, tapioca, cowpea and wheat flours at 25% w/w offer a good compromise between technological and nutritional qualities, while reducing wheat imports and cassava post-harvest losses. These results may herald technologically satisfactory, nutritional, sustainable bakery products.     

Antioxidant Properties of Peptide from Cowpea Seed

The amino acids, hydrophobicity, preparation technology, and antioxidant activity of peptide from cowpea seed isolated protein were investigated. The ratio of essential amino acid to total amino acid of cowpea seed and cowpea seed isolated protein were 35.60 and 36.27%, respectively, and the essential amino acid to non-essential amino acid were 55.27 and 56.96%, respectively. The mole ratio of hydrophobic amino acids and branched chain amino acids in cowpea seed isolated protein were 38.10 and 31.75%. The hydrophobicity value of cowpea seed isolated protein was 5.01 KJ/?mol. The optimum hydrolyzing parameters obtained from orthogonal experiment (L₉(3)⁴) were as follows: hydrolyzing temperature, 50°C; cowpea seed isolated protein concentration, 5%; pH, 9.0; and hydrolyzing time, 2 h. Under optimized conditions, the degree of hydrolysis was 26.85%. Available data obtained with in vitro models exhibited that peptides had significant inhibitory effects on 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radical with half inhibitory concentration (IC₅₀) values of (6.38 ± 0.15) mg/mL and 2.03 mg/mL, respectively, suggesting that cowpea seed peptide possessed higher antioxidative activity and could be used as a potential functional food ingredient.     

Effect of soybean substitution for cowpea on physical,compositional, sensory and sorption properties of<Emphasis Type="Italic"> akara</Emphasis> Ogbomoso

Akara Ogbomoso was prepared from cowpea:soybean flour mixture ratios of 100:0, 80:20, 60:40 and 40:60. Physical, compositional, sensory and sorption characteristics of the akara were evaluated. Protein and fat content increased, while carbohydrate content decreased as the soy content of the flour mixture of akara Ogbomoso increased. There were no significant differences (P<0.01) in the colour, taste, aroma and overall acceptability for either the freshly prepared akara Ogbomoso or the akara Ogbomoso stored for 10 weeks. There were significant differences (P<0.01) in crunchiness, increasing as the soy substitution increased both in the freshly prepared and stored akara Ogbomoso. The adsorption isotherms of akara Ogbomoso varied with varying levels of soy substitution and at 20, 30 and 40 °C, had sigmoid shaped, type II isotherms according to Brunauer-Emmet-Teller (BET) classification, and were affected by temperature and composition. Increased levels of soy substitution and temperature depressed the isotherms. Calculated monolayer moisture contents using BET and Guggenhein Anderson deBoer models decreased with increasing soy substitution and temperature.     

修饰的cpti基因在转基因棉花后代中的表达及其抗虫性分析

对转修饰cpti基因（即sck基因）的抗虫棉T3代进行了分子检测和抗虫性检测，PCR，Southern杂交证明外源基因已稳定遗传给后代植株，抑制剂活性检测表明转sck基因后代比转未修饰cpti基因后代具有更强的县蛋白酶抑制剂活性，抗虫性分析表明，转基因后代对棉铃虫的生长发育具有明显的抑制作用，结果进步说明，将外源蛋白细胞内靶向定位的策略应用于棉花抗虫基因工程，可以提高外源蛋白在细胞内的积累量，进而提高转基因植株及其后代的抗虫性。     

病毒样颗粒限域纳米催化剂提高催化加氢活性

以豇豆褪绿斑驳病毒(CCMV)衣壳蛋白表达基因为模板,构建基因工程菌CCMV-BL21,并通过正交实验优化可溶蛋白表达工艺;采用原位还原法制备病毒样颗粒限域Ru纳米催化剂(Ru@CCMV),以肉桂醛和4-硝基苯酚加氢为模型反应进行评价。目标蛋白的最佳表达条件为:诱导温度25℃,异丙基硫代半乳糖苷(IPTG)终浓度1.0 mmol/L,诱导时间15 h。在该条件下,可溶性蛋白表达量达181 mg/L发酵液,约占表达蛋白总质量的93%。Ru@CCMV在两个反应中均显示较高的催化活性,反应速率常数经计算分别达到0.17 min–1和0.50 h–1,高于柠檬酸修饰Ru纳米颗粒(Ru-CA)催化剂(0.11 min–1和0.36 h–1)。     

Isotopic discrimination associated with symbiotic nitrogen fixation in stylo (Stylosanthes hamata L.) and cowpea (Vigna unguiculata L.)

A glasshouse study was carried out to determine the isotopicdiscrimination (B values) and the isotopic fractionation factors ()associated with symbiotic nitrogen fixation in stylo (Stylosantheshamata L.) and cowpea (Vigna unguiculata L.Walp). The B values are required to improve the accuracy of estimates ofnitrogen fixation based on the differences in the natural abundance of¹⁵N between nitrogen fixing and non-fixing plants. The B values ofplants grown in nitrogen free media for stylo were –1.60, 82 days after planting (DAP) and –1.86, 98 DAP and –1.48, 49DAP and –1.51 for cowpea shoots 73 DAP. Theisotopic fractionation factors for stylo and cowpea were 1.0016, 82DAP and 1.0019, 98 DAP and 1.0018, 49 DAPand 1.0015, 73 DAP, respectively.     

Contact Sex Pheromone Components of the Cowpea Weevil, Callosobruchus maculatus

The cowpea weevil, Callosobruchus maculatus, is a major pest of stored pulses. Females of this species produce a contact sex pheromone that elicits copulation behavior in males. Pheromone was extracted from filter-paper shelters taken from cages that housed females. Crude ether extract stimulated copulation in male C. maculatus. Initial fractionation showed behavioral activity in acidic and neutral fractions. Furthermore, bioassay-guided fractionation and gas chromatography-mass spectroscopy (GC-MS) analysis of active fractions revealed that the active components of the acidic fraction were 2,6-dimethyloctane-1,8-dioic acid and nonanedioic acid. These components along with the hydrocarbon fraction, a mixture of C₂₇–C₃₅ straight chain and methyl branched hydrocarbons, had a synergistic effect on the behavior of males. Glass dummies treated with an authentic pheromone blend induced copulation behavior in males. The potential roles of the contact sex pheromone of C. maculatus are discussed.     

Species diversity and relative abundance of Callosobruchus (Coleoptera: Chrysomelidae) in stored cowpea in four major agricultural produce markets in the central region,Ghana

A study was conducted to investigate species diversity and relative abundance of Callosobruchus (Coleoptera: Chrysomelidae), a major insect pest infesting stored cowpea in the central region of Ghana. Cowpea stocks from Burkina Faso, Ejura, Ghana and Niger were obtained from the markets, and held to collect adults emerging from the cowpeas. Adult Callosobruchus spp. were identified based on the pattern of their hind femora and elytra. Five species, Callosobruchus maculatus, Callosobruchus rhodesianus, Callosobruchus chinensis Callosobruchus analis and Callosobruchus subinnotatus, were identified, with C. maculatus being the most abundant.