Durodoluwa Oyedele

Antihypertensive properties of aqueous extracts of vegetable leaf‐fortified bread after oral administration to spontaneously hypertensive rats

This study investigated the potential cardiovascular health benefits of leavened bread produced from wheat flour that contained 1%, 2% and 3% additions of leafy vegetable powders obtained from Amaranthus viridis (AO), Solanum macrocarpon (SM) or Telfairia occidentalis (TO). Dried breads were extracted with water at 60 °C followed by analysis for total polyphenolic content (TPC), as well as in vitro inhibitions of angiotensin-converting enzyme and renin activities. HPLC analysis of the bread extracts indicated the presence of mainly rutin, gallic acid, myricetin and caffeic acid. TPC of the vegetable-fortified breads was significantly (P < 0.05) higher (5.8–7.6 mg gallic acid equivalent, GAE/g) than that of control bread (5.5 mg GAE/g). Oral administration of 100 mg dried extract/kg body weight to spontaneously hypertensive rats led to reductions (up to 42 mmHg) in systolic, diastolic and mean arterial blood pressure in comparison with 20 mmHg for the control bread.

Analysis of Household Demand for Underutilized Indigenous Vegetables

ABSTRACT Estimation of characteristics of the demand system of underutilized indigenous vegetables (UIVs) is important to understand how they can be better utilized in developing countries. The study analyzed demand responses of households to UIV prices using the quadratic almost ideal demand system (QUAIDS). More than half of respondents were female (65%), monogamously married (68%), between 20 and 39 years of age (57%), with a mean household size of six persons and primarily employed in public service or private companies (53%). The demand for the UIVs was relatively inelastic. All of the vegetables were normal goods and their cross-price elasticities were inelastic and complementary. The UIVs are consumed along with other vegetable crops mostly by a specific consumer group who could be a niche market for the commodity.

The effects of moisture content at tillage on soil strength in maize production

An adequate and balanced supply of moisture is essential for plant growth. Moisture is constantly being taken up by plants together with nutrients and is lost by transpiration. Inadequate moisture coupled with transpiration decreased plant growth rate and the final crop yield [1]. Water serves four general roles in plants: it is the major constituent of the physiologically active tissue; as a reagent in photosynthetic and hydrolytic processes; as a solvent for salts, sugars and other solutes and it is essential for the maintenance of turgidity necessary for cell enlargement and growth [2]. In agricultural systems, soil and crop management practices (crop rotation, residue management, the intensity and frequency of tillage) produce long-term effects on soil quality which may be detrimental or beneficial to our environment. For instance, tillage can degrade soil quality by mechanically destroying soil aggregates and exposing protected soil organic to microbial attack [3]. Compaction and tensile stresses during seedbed preparation drastically altered porosity and pore size distribution due to change in soil volume. However, tillage mixes residue with the soil, aiding decomposition of crop residue and native soil organic matter, thereby enhancing mineralization and release of nutrients [4]. Studies have shown that greater bulk density can be expected in some soil types with no-till compared to plough-till practices [5]. Crusting is a soil surface characteristic that provides information on soil strength or penetration resistance. Higher crust strength has been reported to reduce soil water storage due to the reduction of crust conductance and infiltration rates [6,7]. Tillage systems create an ideal seedbed condition for plant emergence, developments and un-impeded root growth [8]. It is an essential management technique that helps to control weeds and input that also affects soil physical characteristics. However, changes in soil properties differ among management practices [9]. To efficiently handle the demand in agricultural food production, soil physical properties must be managed adequately. The main concern of soil physics in crop productivity is to preserve suitable proportions between solid, liquid and gaseous phases [10]. It was reported that soil physical properties affected by soil tillage treatments, could influence the yields of crops [11]. For instance, soil compaction causes low porosity, reduced infiltration, increase penetration resistance and limit root growth. Soil surface roughness (configuration) influences wind and water erosion by decreasing soil detachment and transport caused by erosion [12]. Low soil moisture content can make the cohesive force between particles of soil to be very strong and a lot of energy is to overcome this during tillage. However, with the higher soil moisture content, the effectiveness of tillage equipment in the field is reduced [13]. In a study at North Dakota, U.S.A, it was concluded that inconsistencies observed in relative grain yield differences among tillage treatments over a period of years were partly associated with inconsistent differences in soil properties produced by given tillage treatments from one year to another [14]. The authors concluded that the observed inconsistencies were likely to be associated with the presence of soil water at the time of tillage distribution and differences in soil temperature. The major contributing factor to the increasing rate of soil degradation in African countries is due to tillage being carried out at inappropriate soil moisture contents. Tillage induced soil compaction is becoming a growing ecological concern because of the steady increase in the weight of machineries used in agriculture. Moreover, soil properties are not considered in purchasing these equipment. This problem is exacerbated by carrying out tillage operations under unfavourable moisture conditions. In Nigeria, no conscious effort has been made to evaluate the appropriate soil moisture conditions for the tillage of bench mark agricultural soils. This study is therefore expected to determine maize yield and soil properties changes resulting from tillage operations carried out at different soil moisture conditions. It is with the view to establishing the optimum range of moisture contents for the cultivation of the selected Alfisol in Ile-Ife area, Nigeria.

Chemical Composition and Quality Characteristics of Wheat Bread Supplemented with Leafy Vegetable Powders

The study investigated the effect of supplementation of the leaf powders of Telfairia occidentalis, Amaranthus viridis, and Solanum macrocarpon on the chemical composition and the quality characteristics of wheat bread. The bread samples were supplemented with each of the vegetable leaf powders at 1%, 2%, and 3% during preparation. The bread samples were assayed for proximate composition, mineral composition, physical, sensory, and antioxidant properties using standard methods. The addition of vegetable powders significantly increased the protein (9.50 to 13.93%), fibre (1.81 to 4.00%), ash (1.05 to 2.38%), and fat (1.27 to 2.00%). Supplementation with vegetable powder however significantly decreased ( ) the carbohydrate and moisture contents. Significant ( ) increases were recorded for all evaluated minerals as the level of vegetable powder increased. Supplementation with vegetable powder caused significant decrease in total phenolic content, percentage DPPH inhibition, metal chelating ability, ferric reducing antioxidant power, and total antioxidant capacity. Sensory results showed that there was significant decrease in sensory qualities with increasing supplementation. This therefore suggests that bread supplemented with vegetable powder could have more market penetration if awareness is highly created.

Optimization of Production of Bread Enriched With Leafy Vegetable Powder

Box-Behnken design was used to study the effect of level of inclusion of dried leafy vegetable powder, mixing time and proofing time, on the weight, volume and specific volume of bread made from composite flour. Data obtained were evaluated using regression analysis. The study revealed all the parameters studied were significant in producing high quality vegetable powder enriched bread. The coefficient determination (R 2 ) was good for the second-order quadratic model. The study found out those combinations of the parameters; level of vegetable inclusion; 3.65%, proofing time: 90.6 minutes and mixing time: 4.04 minutes were the optimal conditions for the productions of high quality bread enriched with vegetable powder. The study further confirmed through additional analysis that the model is adequate to optimize the process.

Incidence and management of plant parasitic nematodes under continuous vegetable production in a rainforest agroecology in Nigeria

Summary Field studies were conducted in 2012 and 2013 in the tropical rainforest zone of Nigeria to investigate the effects of a composted, pelletised organo-mineral fertiliser applied as an organic amendment at 5 metric tonnes (MT) ha-1 or at 10 MT ha-1 in four replications, on soil population densities of five genera of plant-parasitic nematodes and on crop yields of Telfairia occidentalis (fluted pumpkin). The experimental field was naturally infested with Meloidogyne incognita, Tylenchus spp., Helicotylenchus spp., Hirschmaniella spp., and Longidorus spp. The compost was applied as an amendment to soil planted with T. occidentalis 3 weeks after seedling emergence. At the end of both annual experiments, the addition of compost as a soil amendment resulted in 16.25 - 65.75% reductions in the populations of all five genera of plant-parasitic nematodes compared to an increase in each nematode population in the untreated control plots. There was also a higher crop yield of T. occidentalis in all eight treated plots compared to the control plots. Compost applied at 10 MT ha-1 reduced the soil populations of all nematode species significantly, with correspondingly higher yields of the crop compared to 5 MT compost ha-1 in both years of study. Correlation analysis showed that the population density of each nematode species had a negative effect on the cumulative leaf biomass (fresh weight) of the test crop. The results of this study suggest that nematodes constrained the production of T. occidentalis under continuous cropping and that a composted, pelletised organo-mineral fertiliser, applied as a soil amendment at 10 MT ha-1, suppressed soil populations of all five nematodes significantly and increased yields of T. occidentalis by 109 - 366% compared to the untreated control plots.

Information Use for Marketing Efficiency of Underutilized Indigenous Vegetable

ABSTRACT The role of marketing information on the marketing efficiency of underutilized indigenous vegetables requires clarification so that an appropriate marketing extension services model can be developed. Responses from 206 marketers indicated that types of marketing information used included information on price, quantity to buy, and quantity and where to sell. The marketing is efficient as determined by the conventional, Shepherd’s, and Acharya’s methods while information on where to sell beneficially affected efficiency. Empirical data were developed that can be used to develop appropriate marketing extension services for farmers and marketers.

Technical Efficiency in Production of Underutilized Indigenous Vegetables

ABSTRACT Increased efficiency and productivity in agriculture are important to food security. Technical efficiency, as it affects sustainable production of selected underutilized indigenous vegetables, using innovative production practices or not, was analyzed. Primary data were collected from 300 respondents using questionnaires. The data were interpreted with a stochastic production frontier analysis and difference of means. A mean technical efficiency score of 74% for users versus 56% for nonusers incorporating innovative production practices in their operations indicated that users were more technically efficient. Opportunities exist to increase productivity in indigenous vegetable production through more efficient inputs utilization.

Extraction Optimization and Antioxidant Properties of African Eggplant (Solanum macrocarpon) Leaf Polyphenols

Optimization of the yield, total phenolic content (TPC), and total antioxidant activities (TAA) of polyphenol concentrates extracted from Solanum macrocarpon leaves was studied using response surface methodology. The process variables investigated included extraction temperature (30, 50, and 70°C), extraction time (2, 4, and 6 h), and dried leaf powder : water ratio (1 : 10, 1 : 20, and 1 : 30 w/v). Box–Behnken design resulted in 15 experimental runs. The results showed the following optimum extraction conditions: temperature, 49.05°C; extraction time, 243 min; leaf powder : water ratio, 1 : 22 w/v. The optimized extraction conditions gave polyphenol concentrate yield, TPC, and TAA values of 24.94%, 421.09 mg GAE/g, and 23.81 mg AAE/g, respectively. Results of the in vitro antioxidant activities of the polyphenol concentrate showed 2, 2-diphenyl-2-picrylhydrazyl hydrate, metal chelating ability, and ferric reducing ability values of 76.78%, 80.22%, and 56.46 mg AAE/g, respectively. The study concludes that the experimental values compared closely with the predicted values, which indicates suitability of the model employed for polyphenol extraction optimization from dried S. macrocarpon leaves.