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John Muyonga

Background: Jackfruit (Artocarpus heterophyllus Lam) is widely cultivated in tropical and sub-tropical areas worldwide. The tree is highly productive, resilient, and requires minimal care. Jackfruit has a characteristic flavour and is... more
Background: Jackfruit (Artocarpus heterophyllus Lam) is widely cultivated in tropical and sub-tropical areas worldwide. The tree is highly productive, resilient, and requires minimal care. Jackfruit has a characteristic flavour and is highly versatile. Several studies report the importance of the tree and fruits, ranging from food and medicine to the provision of several value-added products. In spite of the many benefits the plant offers, it has not been sufficiently incorporated in the general food system, partly because of gaps in processing, distribution and knowledge about utilization methods and nutritional and nutraceutical value. Objective: A comprehensive literature search was done to highlight jackfruit's nutritional, health, and commercial benefits to promote its utilization. Methodology: The literature search was conducted using three electronic databases with no constraints on publication year. Over 200 studies on the nutritional properties of jackfruit and at least ...
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... 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...
Drying processes including solar, oven, and refractance window were studied to determine their influence on the drying behavior of jackfruit slices and properties of resultant jackfruit powders. The loss of sample mass, converted to the... more
Drying processes including solar, oven, and refractance window were studied to determine their influence on the drying behavior of jackfruit slices and properties of resultant jackfruit powders. The loss of sample mass, converted to the ratio between the water content at time t and the initial water content (moisture ratio), was used as the experimental parameter for modelling drying processes. Fifteen thin layer drying models were fitted to the experimental data using nonlinear regression analysis. Based on the highest R 2 and lowest SEE values, the models that best fit the observed data were Modified Henderson and Pabis, Verma et al., and Hii et al. for RWD, oven, and solar drying, respectively. The effective moisture diffusivity coefficients were 5.11 × 10 − 9 , 3.28 × 10 − 10 , and 2.55 × 10 − 10 for RWD, oven and, solar drying, respectively. The solubility of freeze-dried jackfruit powder (75.7%) was not significantly different from the refractance window dried powder (73.2%) a...
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... 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...
Purpose: Transformation of pumpkin flesh and seeds into dry flours increases their shelf stability and versatility. This study sought to optimise drying conditions for production of flour with high nutritional and nutraceutical value from... more
Purpose: Transformation of pumpkin flesh and seeds into dry flours increases their shelf stability and versatility. This study sought to optimise drying conditions for production of flour with high nutritional and nutraceutical value from flesh and seeds of C. pepo L var. fastigata using Response Surface Methodology, I optimal design. Research Method: Pumpkin flesh and seeds were dried following temperature time combinations got using I optimal design. All dry samples were tested for ascorbic acid, total carotenoids, total antioxidant capacity and starch digestibility. Seeds were also tested for in vitro protein digestibility, trypsin inhibitor activity, alpha tocopherol, beta tocopherol, and alpha tocotrienol. Findings: The predicted optimum drying conditions for production of C. pepo L var. fastigata flour with maximum nutritional quality and bioactivity were 57°C; 6.9 hours for flesh and 60°C; 3.15 hours for seeds. The most influential model terms were temperature for resistant s...
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... 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...
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... 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...
... USA. pp. 638-653. Ameny, MA & Wilson, PW 1997. ... London, UK. pp. 391-397. Tushemereirwe, WK, Karamura, D., Ssali, H., Bwamiki, D., Kashaija, C., Nankinga, C., Bagamba, F., Kangire, A & Ssebuliba, R. 2001. Mukiibi... more
... USA. pp. 638-653. Ameny, MA & Wilson, PW 1997. ... London, UK. pp. 391-397. Tushemereirwe, WK, Karamura, D., Ssali, H., Bwamiki, D., Kashaija, C., Nankinga, C., Bagamba, F., Kangire, A & Ssebuliba, R. 2001. Mukiibi (ed). Agriculture in Uganda. Volume 2. Crops. NARO. pp. ...
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)... 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 ...
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... 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...
Small scale food processing is characteristic of many enterprises in Uganda. As such, the Food Technology Business Incubation Centre (FTBIC), at Makerere University offers food processing entrepreneurs an opportunity to learn practical... more
Small scale food processing is characteristic of many enterprises in Uganda. As such, the Food Technology Business Incubation Centre (FTBIC), at Makerere University offers food processing entrepreneurs an opportunity to learn practical skills that are indispensable in food processing value chains. Despite the good intensions, FTBIC organic waste, is a menace and a source of pests. The main goal of this study was to determine the most appropriate and optimum ratios of organic wastes for production of biogas to be converted to meet heating needs of FTBIC. The samples of organic waste were quantified and characterized for their potential to generate biogas. Nine treatments in duplicate without inoculum were selected for production of biogas in the ratios: pineapples and other waste 3:1 (A1), 1:1 (A2), and 1:3 (A3); Mangoes and other wastes 3:1 (B1), 1:1 (B2), and 1:3 (B3); and orange and other wastes 3:1 (C1), 1:1 (C2) and 1:3 (C3). Other wastes included: Irish potatoes, bananas, veget...
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... 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. ...
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... 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...
This study aimed at understanding peel and flesh characteristics of Cucurbita maxima Duchesne subsp maxima, Cucurbita pepo L var. fastigata and Cucurbita moschata Decne pumpkin varieties and how the fruit characteristics relate to its... more
This study aimed at understanding peel and flesh characteristics of Cucurbita maxima Duchesne subsp maxima, Cucurbita pepo L var. fastigata and Cucurbita moschata Decne pumpkin varieties and how the fruit characteristics relate to its postharvest stability. Mature fruits were stored at ambient conditions (28oC and 78% Relative humidity) for eight months. Cell microscopic structure, intercellular space size, sugars, starch, cellulose, hemicellulose, lignin, degree of esterification of pectin, polygalacturonase activity, and cumulative moisture lost were determined monthly. Sucrose, starch, cellulose and hemicellulose content and degree of esterification of pectin of different varieties decreased with storage. Glucose and fructose content increased to a maximum and then reduced. Polygalacturonase activity and lignin generally increased with storage time. Size of intercellular spaces, and cumulative moisture lost from both flesh and peel increased with storage. Sucrose breakdown was ke...
The nutritional state of large segments of the African population remains alarming despite the positive socio-economic development that is taking place. The most significant nutritional problems include undernutrition, iron deficiency and... more
The nutritional state of large segments of the African population remains alarming despite the positive socio-economic development that is taking place. The most significant nutritional problems include undernutrition, iron deficiency and vitamin A deficiency. Malnutrition and deficiencies also exacerbate a number of other diseases and health conditions. Besides undernutrition, the prevalence of overnutrition and obesity on the African continent are rising, as are the associated health conditions such as diabetes and coronary heart diseases. This chapter outlines the unique nutritional and bioactive properties of Traditional African Foods (TAFs) and their potential to contribute to the alleviation of undernutrition, overnutrition and associated health problems. Special emphasis is placed on vegetables, fruits, cereals, edible insects, small fish species, mushrooms, legumes, sesame, tuber and root crops. Some of the identified health benefits of these TAFs include lowering of serum c...
ABSTRACT
ABSTRACT
... JM Ssebuliba, ENB Nsubuga 1 and JH Muyonga 2 Department of Crop Science, Makerere University, PO Box 7062, Kampala, Uganda 1 Department of Agricultural ... b-carotene content of the sweetpotato cultivars was determined by... more
... JM Ssebuliba, ENB Nsubuga 1 and JH Muyonga 2 Department of Crop Science, Makerere University, PO Box 7062, Kampala, Uganda 1 Department of Agricultural ... b-carotene content of the sweetpotato cultivars was determined by spectrophotometry (Ameny and Wilson, 1997 ...
Fatty material from Nile perch belly flaps, a major processing by‐product, was assessed for variation in fat content, fatty acid composition, vitamin A content, and level of contaminants in relation to capture site and season. Nile perch... more
Fatty material from Nile perch belly flaps, a major processing by‐product, was assessed for variation in fat content, fatty acid composition, vitamin A content, and level of contaminants in relation to capture site and season. Nile perch from Lake Victoria had higher material yield and omega-3 fatty acids (FAs) but lower content of vitamin A than those from Lake Albert.
Four common bean (Phaseolus vulgaris L.) varieties, Kawanda (K)131, K132, NABE4 and NABE11, were evaluated for the relationship between development of the hard-to-cook (HTC) defect and changes in nutritional quality during 6-month storage... more
Four common bean (Phaseolus vulgaris L.) varieties, Kawanda (K)131, K132, NABE4 and NABE11, were evaluated for the relationship between development of the hard-to-cook (HTC) defect and changes in nutritional quality during 6-month storage under ambient conditions. All varieties developed the HTC defect, but the extent was found to vary with variety. Cooking time increased by 113% in K131, 95.3% in K132, 56.4% in NABE4 and 42.93% in NABE11 after 6 months. The development of the HTC defect was found to be associated with a reduction in phytic acid content (r2 = -0.802), in vitro protein digestibility (r2 = -0.872) and in vitro starch digestibility (r2 = -0.729). The susceptibility to the HTC defect during storage could be attributed to a phytic acid interaction with proteins and carbohydrates, and is also associated with small seed size. Breeding for large seed size could therefore help reduce the development of the HTC defect.
... and in addition creating a value-added product. Recent outbreaks of Bovine spongiform encephalopathy (BSE) and increase in demand for kosher and halalfoods have created a demand for fish gelatin for food applications. ...

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