John Muyonga - Academia.edu (original) (raw)

Papers by John Muyonga

African Crop Science Journal

African forests act as sources of both plant and animal foods that provide significant amounts of... more African forests act as sources of both plant and animal foods that provide significant amounts of nutrients and healthy boosting bioactive compounds. This study investigated the relationship between knowledge, perceptions and socio-demographic attributes towards consumption of forest foods. A total of 279 females in charge of decision making with respect to food preparation, were randomly selected from 12 villages in southern and eastern Cameroon, and interviewed using researcher administered questionnaires. Multivariate logistic regression analysis was used to identify the socio demographic factors and perceptions affecting consumption of forest foods. Baillonella toxisperma (African pearwood) (98%), Irvingia gabonesis (bush mango) (81%) and Trichoscypha abut (Mvout) (70%) were identified as the most nutritious foods. Among the animal forest foods, bush meat (11%) and Imbrasia spp. (edible caterpillars) (10%) were identified as the most nutritious. Consumption of forest foods was higher among polygamous families and also positively related to length of stay in the forest area, as well as age of female respondents. Education had an inverse relationship with use of forest foods. Perception towards the nutritional value of forest foods were also found to positively influence consumption of forest foods. Since negative perceptions were found to influence consumption, there is need to invest in awareness campaigns to strengthen the current knowledge levels among the study population.

Current Developments in Nutrition

Food Science & Nutrition

School‐age children frequently consume snacks. However, most of the snacks they consume are of lo... more School‐age children frequently consume snacks. However, most of the snacks they consume are of low nutritional quality. The objective of this study was to develop a nutrient‐rich and acceptable extruded bean‐based snack, which could contribute to improved nutrient intake, especially for school‐age children. Snack formulations developed from Roba1 beans, maize, orange‐fleshed sweet potato, and amaranth mixtures, and processed in a twin‐screw extruder, were evaluated and optimized for nutritional, textural and sensory properties. High proportion of beans in the formulation was associated with high protein, iron, zinc, and dietary fiber content. An optimal formulation (82.03:10: 5:2.97; beans, maize, OFSP, amaranth), containing 20.38 g, 4.12 g, 4.83 mg, and 1.51 mg per 100 g, of protein, dietary fiber, iron, and zinc, respectively, was obtained. The snacks were crunchy and moderately acceptable with average sensory scores of 6 on a 9‐point hedonic scale, and hardness 26.6 N. Nutrient c...

African eggplant (Solanum anguivi Lam.) fruits reportedly exhibit antidiabetic properties, possib... more African eggplant (Solanum anguivi Lam.) fruits reportedly exhibit antidiabetic properties, possibly due to the presence of bioactive compounds. This study aimed to assess the bioactive compounds content (BCC) and antioxidant activity (AA) in the fruits of fourteen African eggplant accessions. The relationship between the fruit BCC and AA, and the plant (leaf, stem and fruit) morphological characteristics was determined. Morphological traits for the plant accessions were characterized based on existing Solanum species descriptors. Total phenolics, flavonoids, saponins, vitamin C and AA were determined by spectrophotometry, while total alkaloids were detected by gravimetry. HPLC was used for the quantification of phenolic compounds. Morphological characteristics, BCC and AA differed among the accessions. The fruit's accessions contained total phenolics (8.0-12.4 mg gallic acid equivalent/g dry weight (DW)), saponins (51.1-124.8 mg diosgenin equivalent/g DW), alkaloids (81.4-127.7 ...

Molecules

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder of glucose homeostasis associated... more Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder of glucose homeostasis associated with a status of insulin resistance, impaired insulin signaling, β-cell dysfunction, impaired glucose and lipid metabolism, sub-clinical inflammation, and increased oxidative stress. Consuming fruits and vegetables rich in phytochemicals with potential antidiabetic effects may prevent T2DM and/or support a conservative T2DM treatment while being safer and more affordable for people from low-income countries. Solanum anguivi Lam. fruits (SALF) have been suggested to exhibit antidiabetic properties, potentially due to the presence of various phytochemicals, including saponins, phenolics, alkaloids, ascorbic acid, and flavonoids. For the saponin fraction, antidiabetic effects have already been reported. However, it remains unclear whether this is also true for the other phytochemicals present in SALF. This review article covers information on glucose homeostasis, T2DM pathogenesis, and als...

$Research paper thumbnail of Adoption of the Refractance Window Drying Technology in the Drying of Fruits and Vegetables in Uganda$

Journal of Advances in Food Science & Technology, Jun 18, 2021

International Journal of Agricultural and Biological Engineering, 2016

In this study, an integrated approach incorporating Remote Sensing (RS), Geographical Information... more In this study, an integrated approach incorporating Remote Sensing (RS), Geographical Information System (GIS), local meteorological weather stations’ data and NASA’s virtual meteorological stations’ data were used to quantify Grain Amaranth (GA) water requirements in Uganda. Penman-Monieth method within CropWAT8 model and Surface Energy Balance Algorithm for Land (SEBAL) Model was used to quantify the evapotranspiration. Normalized Difference Vegetation Index (NDVI), daily spatial distribution of Evapotranspiration (ET), Land Surface Temperature (LST) and surface albedo were extracted from satellite imagery. The ratio of effective rainfall (Pe) to Potential Evapotranspiration (PET) – (Pe/PET) and time series for NDVI were computed to determine the growth stage of GA in different areas. The GA water demand was the highest in Karamoja sub-region (467.5 mm/season) and the lowest in Tororo (174.1 mm/season). The growing season for GA in most areas of Uganda was from March to December. ...

Asian Journal of African Studies, 2010

This project undertook a survey in Rachuonyo (Kenya), Bukoba (Tanzania) and Rakai (Uganda) distri... more This project undertook a survey in Rachuonyo (Kenya), Bukoba (Tanzania) and Rakai (Uganda) districts to assess the contribution of banana to the household food security and nutrition of PLWHA and assessed the potential nutritional benefit of providing nutrient enhanced banana to PLWHA. Data were collected through interviews with 373 PLWHA and key informants (local agricultural support staff and personnel from PLWHA support agencies) and using focus group discussions. A banana based nutrient enhanced food supplement made by blending banana flour (61%) with soybean flour (39%) and multi?.nutrient fortificant pre?.mix (0.2% of mixture) was distributed to 15 respondents and their nutrient intake estimated. The majority (71.5%) of the survey respondents were females aged 20-50 years; most had no higher than primary level education and the majority were small scale farmers (with gardens ＜1 acre). Most of the respondents produced and consumed bananas. The study population was generally foo...

$Research paper thumbnail of Drying behaviour and optimization of drying conditions of pineapple puree and slices using refractance window drying technology$

Journal of Food Science and Technology, 2021

Refractance window drying technology can be used to produce high quality dried fruit products due... more Refractance window drying technology can be used to produce high quality dried fruit products due to its excellent retention of heat sensitive nutrients, organoleptic properties and bioactive compounds. This study optimised conditions for drying of pineapple slices and puree using RWDT. i-optimal design in Design Expert software was used to generate temperature-thickness combinations in form of runs. The independent factors considered included drying temperature (70-90°C) and thickness (2-3 mm), and the responses included drying time and vitamin C concentration. The optimum solutions generated for RW drying temperature and pulp thickness were 86.2°C and 2.9 mm for puree and 78.9°C and 2 mm for slices. The drying times for puree and slices were 58 and 96 min, respectively with corresponding vitamin C content of 64.88 and 46.83 mg/100 g. Drying kinetics of puree and slices were determined at optimal conditions. Drying was found to follow Modified Midilli et al. Model. Pineapple powder obtained using optimal RWD conditions had low water activity (0.41), high solubility (74.64%) and dehydration ratio (4.12). Pineapple reconstituted drinks were developed and evaluated for consumer preference. Acceptability was highest at 15% inclusion of pineapple powder.

$Research paper thumbnail of Design and evaluation of a refractance window lab-scale dryer$

Journal of Engineering, Design and Technology, 2021

Purpose Refractance window drying (RWD) has been identified as the method that can give high-qual... more Purpose Refractance window drying (RWD) has been identified as the method that can give high-quality products at a relatively low production cost. However, knowledge about its use and adoption remains lacking both in academic curricula and industry in the developing world. Design/methodology/approach A lab-scale batch RWD of a closed-loop control system was designed, fabricated and evaluated for drying rates, evaporation rate, the energy of evaporation, energy efficiency and throughput. Testing was done using mango and tomato pulps. Findings Drying rates at 95°C of 1.32 gg−1min−1 and 0.854 gg−1min−1 at 2 and 3 mm, respectively, for tomato, 0.6 gg−1min−1 and 0.33 gg−1min−1 at 2 and 3 mm for mango pulp were obtained. The dryer had an evaporation rate of 4.63 × 10–4 kg/s and 4.25 × 10–4 kg/s, the energy of evaporation of 1.05 kW and 0.96 kW and thermal energy efficiency of 25.64% and 21.73% while drying tomato and mango pulps, respectively. Dryer throughput of 0.6 kg/h of dried mango P...

Food Science & Nutrition, 2019

The study was designed to optimize extrusion processing conditions for production of instant grai... more The study was designed to optimize extrusion processing conditions for production of instant grain amaranth flour for complementary feeding. Multi‐response criteria using response surface methodology and desirability function analysis were employed during the study. The central composite rotatable design (CCRD) was used to determine the level of processing variables and to generate the experimental runs. The process parameters tested included extrusion temperature (110–158°C), screw speed (40–52 Hz), and feed moisture content (11%–16%), while response variable was protein digestibility, sensory acceptability, water absorption index, water solubility index, bulk density, and viscosity. Data obtained from extrusion were analyzed using response surface methodology. Data were fitted to a second‐order polynomial model, and the dependent variables expressed as a function of the independent variables. Analysis of variance (ANOVA) revealed that extrusion parameters had significant linear, q...

African Journal of Food, Agriculture, Nutrition and Development, 2019

Jackfruit originated from East Asia, known to be the largest tree born fruit weighs up to 30kg an... more Jackfruit originated from East Asia, known to be the largest tree born fruit weighs up to 30kg and yields 50-80 tons per hectare annually. The fruit has large potential in Uganda and has been used in value added products on a small and rudimentary scale. This work assessed the production and utilization patterns of jackfruit with a view of determining its capacity to sustain industrial scale processing. A cross-sectional survey was conducted in jackfruit producing regions from April to June 2016. The study variables were household farm size, number of jackfruit trees, types, utilization methods and constraints associated with jackfruit production. A purposive sampling design was used to select districts, sub-counties, parishes and villages to participate in the survey. A total of 400 household heads from the study area were interviewed using a semi structured questionnaire. Responses and observations were recorded; secondary data was also reviewed for information on the total number of households in a district. The results showed that 32% of the respondents worked on 1-2 acres of farmland on which they have at least 2-7 jackfruit trees. About 57% of jackfruit trees were planted while the remaining 43% were inherited. The study area was estimated to have about 1.7 million fruiting jackfruit trees with the number of fruits per tree varying between 20-120 fruits and weighing11 kg, on average. Jackfruit harvest season in Uganda has two peaks in March to April and November to December, with the latter season yielding more fruit. Jackfruit is categorized into white, orange and yellow types based on the pulp color, hard or soft according to pulp texture. About 78% of households produced jack fruit mainly for home consumption, 16% of the households sold the fruit, and 6% fed it to animals while 1% of the household processed them into dried chips or jackfruit wine. The estimated jackfruit production per district in the study area was 0.3 million metric tons/annum. Although the study area has a potential of producing jackfruit for industrial processing, there is need to grow more jackfruit in an organized manner to meet the increasing and competing demands for both home consumption and industrial processing.

BBA Clinical, 2017

Objectives: 1. Evaluate the effect of washing and cooking iron-fortified rice on iron retention a... more Objectives: 1. Evaluate the effect of washing and cooking iron-fortified rice on iron retention and bioavailability. 2. Evaluate the effect of iron-fortified rice on women with iron deficiency anemia Methods: 1. Iron-fortified rice (18 mg/100 g as FeSO 4) was cooked in Baton Rouge, Louisiana (C), rinsed and cooked (RC), fried and cooked (FC), cooked with extra water (CW), or soaked and cooked with extra water (SCW), and iron retention was determined. 2. Rice samples were cooked in Kampala, Uganda in a lab (C-Uganda) and households using traditional cooking method (TC-Uganda) and iron retention were determined. 3. Seventeen women with iron deficiency (low iron and/or low ferritin) anemia were randomized to 100 g/d of rice (two cooked 0.75 cup servings) for two weeks containing 18 mg/d iron (supplemented) or 0.5 mg/d iron (unsupplemented). Hemoglobin and hematocrit were evaluated at baseline and 2 weeks with other measures of iron metabolism. Results: 1. Iron retention, from highest to lowest, was (C), (RC), (FC), (C-Uganda), (CW), (SCW) and (TC-Uganda). 2. Seventeen women were randomized and 15 completed the study (hemoglobin 10.6 ± 1.6 g, hematocrit 33.7 ± 4.1%), 9 in the iron-fortified rice group and 6 in the un-fortified rice group. The iron-fortified group had a greater increase in hemoglobin (0.82 g, p = 0.0035) and Hematocrit (1.83%, p = 0.0248) with directional differences in other measures of iron metabolism favoring the iron-fortified group. Conclusions: Iron-fortified rice increased hemoglobin and hematocrit in women with iron-deficient anemia. Iron deficiency and anemia are widespread in Southeast Asia and Africa and undermine development in these regions.

Food Science & Nutrition, 2015

Tamarind seeds are not consumed despite their high antioxidative activity. In this study, 0–10% t... more Tamarind seeds are not consumed despite their high antioxidative activity. In this study, 0–10% tamarind seed powder (TSP) was incorporated into mango juice and cookies. Total phenolics (Folin–Ciocalteu assay), antioxidant activity (2,2‐diphenyl‐1 picrylhydrazyl (DPPH) radical scavenging assay), flavonoid (aluminum chloride assay), condensed tannins content (Vanillin‐HCl assay), and consumer acceptability (n = 50) of the products were determined. TSP increased the pH and viscosity and reduced titratable acidity of juice. Incorporation of TSP increased the: total phenolic content (6.84 ± 0.21 to 88.44 ± 0.8 mg GAE/100 mL); flavonoid (4.64 ± 0.03–21.7 ± 0.36 mg CE/100 mL); condensed tannins (0.24 ± 0.01–21.81 ± 0.08 mg CE/100 mL) and total antioxidant activity (4.65 ± 0.88–21.70 ± 0.03 mg VCE/100 mL) of juice. A similar trend was observed for cookies. Maximum sensorially acceptable TSP levels were 1.5% and 6%, respectively, for juice and cookies. TSP can thus be utilized as a source o...

African Crop Science Journal, 2002