Research Repository :: Browsing by Author "Kibazohi, Oscar"

Browsing by Author "Kibazohi, Oscar"

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Aflatoxin B1 variations in animal feeds along the supply chain in Tanzania and its possible reduction by heat treatment
(Taylor & Francis, 2022-03-04) Mwakosya, Anjelina W; Limbu, Samwel M; Majaliwa, Nuria; Zou, Xiaobo; Shi, Jiyong; Kibazohi, Oscar
This study evaluated the presence of aflatoxin B1 in five different animal feeds collected from manufacturers, suppliers and consumers and its possible reduction by heating at 100°C for 180 min. A total of 160 animal feed samples were collected and analyzed by using lateral flow immunoassay method. The results revealed that all animal feeds analyzed were positive for aflatoxin B1 with 91% samples containing high concentrations ranging from 24.00 to 76.23ng/g above the international allowable standard for animal feeds (20 ng/g). Maize bran (76 ng/g) and sunflower cake (63 ng/g) had higher aflatoxin B1 concentrations, correlating with higher moisture content. Upon heating the feeds, aflatoxin B1 was reduced to a concentration ranging from 2.24 to 9.78 ng/g (<20 ng/g). Our study suggests high potential health problems to animals and humans from aflatoxins requiring proper heating and frequent monitoring of the animal feeds for aflatoxin B1.
Co-composting of banana peel and orange peel waste with fish waste to improve conversion by black soldier fly (Hermetia illucens (L.), Diptera: Stratiomyidae) larvae
(Elsevier, 2021-08-11) Isibika, Alice; Vinnerås, Björn; Kibazohi, Oscar; Lalander, Cecilia; Christian, Zurbrügg
Black soldier fly (BSF) larvae composting is a promising waste treatment that can add value to available biodegradable waste. However, substrates that have low protein content and contain complex molecules (e.g. fruit peels) are not easily degraded by the larvae. This study evaluated the impact on the BSF larvae composting efficiency of co-composting different mixtures of banana and orange peels with incremental increase of fish waste. Mixtures (in total 50 distinct mixtures) of varying proportions of banana peels, orange peels and fish waste were evaluated. BFSL fed on orange peel and banana peel mixtures, containing no fish waste, resulted in a lower biomass conversion efficiency (4.5% ± 1.3) on a volatile solids (VS) basis (BCEvs). Co-composting the fruit peels with fish waste increased the biomass conversion efficiency and the highest BCEvs (25%) was attained when 75% fish waste was included. However, the BCEvs varied greatly (18.0% ± 5.8), likely due to varying fish waste composition. A 25% fish waste inclusion resulted in more than twice as high BCEvs (12.3% ± 2.1) compared to when no fish waste was included. As the conversion efficiency variance increased with increasing fish waste inclusion, it was recommended to keep the inclusions of the fish waste to around 25% of the total mixture, in order to increase the reliability of the BSF larvae composting efficiency.
Effects of Ripeness and Blending Speed on the Extraction Yield and Physical Chemical Properties of Low Viscosity Banana Juice
(College of Natural and Applied Sciences, University of Dar es Salaam, 2021-12) Kibazohi, Oscar; Matabura, Victor V
Low viscosity banana juice can be extracted from banana by blending and pressing the resulted semi-solid pulp to separate the juice. This juice extraction technology is relatively new and further studies to understand key parameters for juice release is vital for scaling up production and commercialisation. This study, investigated the influence of blending speed and ripeness stage on banana juice yield using two banana cultivars; the East African highland banana (Mbile) and the exotic banana (Pisang awak). Types of sugars and organic acids in the juice were analysed using an HPLC. Changes with ripening of fruit firmness, juice pH and soluble solids were also examined. The juice yield increased significantly (p < 0.05) with increasing blending speed and ripeness stage for all cultivars. The Mbile cultivar from Kagera had the highest juice yield of 82.35%, followed by Mbile cultivar from Kilimanjaro with 75.30% and Pisang awak cultivar with juice yield of 62.50%. The highest juice yield for all cultivars was achieved at 3500 rpm blending speed and ripeness stage 5. Fructose and glucose sugars increased significantly (p < 0.05) with ripeness, while sucrose showed insignificant changes. Malic and citric acids were observed to increase significantly (p < 0.05) during ripening in all banana cultivars.
Estimation of Nitrogen Requirement in Peat and Perlite Biofilters Removing Hexane from Air
(Springer Netherlands, 2001) Kibazohi, Oscar; Anderson, William A.; Moo-Young, M.
Biofiltration experiments to remove hexane from air were conducted in column reactors packed with peat, perlite and their mixture. The particle size of the solid medium ranged from 1.70 to 4.75 mm, and the average empty bed superficial velocity was 20 m/h. To achieve and maintain a high rate of hexane removal, addition of nutrient solution was necessary. Adding a nutrient solution of a commercial fertilizer containing 1000 g of nitrogen for the first two weeks, followed by a weekly addition of 280 g of nitrogen per m3 of filter bed was found to be effective in maintaining a high hexane removal rate between 20 and 30 g/m3.h. The hexane removal rate decreased gradually to less than 15 g/m3.h in 50 days due to an accumulation of biomass in the reactors. Pressure drop, which varied depending on the type of packing, also increased drastically to maximum values of 120 Pa/m for 100% perlite and 2930 Pa/m for the mixture. For long-term operation and low energy cost, prevention of biomass accumulation and maintenance of low pressure drop is essential. When the frequency of nutrients addition was reduced excessive biomass growth, and increase in pressure drop with time were controlled. Our observations showed that addition of a nitrogen source of approximately 1 kg of nitrogen per m3 of filter bed for the first and second weeks, and every 30 days (approximately) resulted in an extended life and slightly lower hexane removal. The columns packed with peat and the mixture showed a better hexane removal than the column packed with perlite alone. However, the column packed with perlite had the lowest pressure drop.
Nitrification-Denitrification in a Coupled High Rate - Water Hyacinth Ponds
(Elsevier, 2014) Mayo, Aloyce W.; Hanai, E. E.; Kibazohi, Oscar
Nitrogen transformation was studied in a coupled high rate and water hyacinth (Eichhornia crassipes) ponds at the University of Dar es Salaam. Samples of wastewater were collected and examined for water quality parameters which were used as input parameters in a mathematical model. A conceptual model was then developed to model various processes in the system using STELLA 6.0.1 software. The studGupta and Sujathay demonstrated the dominant nitrogen transformation process in high rate pond (HRP) was nitrification, but denitrification dominated in water hyacinth pond (WHP). In a HRP denitrification and volatilization accounted for 69.1% and 23.8% of removed nitrogen, respectively. On the other hand, denitrification and net sedimentation were the major nitrogen removal mechanisms in WHP accounting for 81.9% and 13.1% of removed nitrogen, respectively. Model results indicated that 1.22 g N/m2 day and 0.37 g N/m2 day of nitrogen was removed in presence and absence of biofilm, respectively. The decrease in nitrogen removal in absence of biofilm, demonstrates the importance of biofilm attached onto plants. It was concluded that incorporation of HRP improved denitrification in WHP because it enhanced formation of more nitrates in HRP in order to promote denitrification in wetland unit due to anoxic conditions.
Physico-chemical Properties of Mechanically Extracted Banana Juice at Different Ripening Stages
(College of Natural and Applied Sciences, University of Dar es Salaam, 2021-12) Mathias, Mathayo G; Kaale, Lilian D; Kibazohi, Oscar
This paper presents the findings of a study on physico-chemical properties of low viscosity banana juice from five banana cultivars: Pisang Awak (PSA) an ABB genome, Yangambi km5 (YKM5) an AAA genome and cultivars from AAA-EA genome, namely Mbilabile, Ndeshi and Mlonga. Low viscosity banana juice was extracted using improved mechanical method at five ripening stages. The physico-chemical properties significantly varied according to cultivars and ripening stages (p < 0.05). Yields, total soluble solids (TSS), titratable acidity (TA) and pH were in the range of 19.50–74.03%, 7.33–27.64 oBrix, 0.37–0.76% malic acid equivalent and 4.09–4.70, respectively. Yields decreased in the order of Mbilabile > Ndeshi > Mlonga > YKM5 > PSA whereas the total soluble solids increased as follows Mlonga < Mbilabile < Ndeshi < YKM5 < PSA. Furthermore, ashes and mineral contents decreased with ripening stages whereas the low viscosity banana juice was rich in potassium and magnesium. Finally, the study recommends stage 5 of the ripeness as ideal for producing low viscosity banana juice.
Proximate composition, pasting and functional properties of composite flour blends from cassava and chia seeds flour
(Sage Publications, 2021-12-07) Rweyemamu, Leonard MP; Kibazohi, Oscar; Katunzi-Kilewela, Ashura; Kaale, Lilian D; Fortunatus, Roman M
The study established the proximate composition, pasting, and functional properties of cassava flour (CF) blended with chia seeds flour (CSF). Composite flour was prepared by blending CF with CSF in the ratios of 95:05, 90:10, 85:15, 80:20, and 75:25 with CF and CSF used as controls, respectively. The effect of blending significantly (p < 0.05) increased protein, fat, fibre, and ash contents as CSF increased. On other hand, moist- ure and carbohydrate contents decreased significantly. Pasting properties of composite flour blends decreased significantly (p<0.05) as the incorporation of CSF increased and a noticeable change was observed for composite flour (75:25) except for peak time and pasting temperature. Functional properties of water absorption capacity (WAC) of CSF were significantly different with CF and composite flour blends. Oil absorption capacity (OAC) of CF and CSF were significantly different, while the composite flour blends had varied OAC due to the inclusion of the different amounts of CSF. The swelling capacity (SC) of CF and CSF were not significantly different, but composite flour blends were significantly different from both CSF and CF. The least gelation concentration (LGC) and bulk density (BD) increased significantly as chia seeds increased. Increased concentration of chia CSF in the composite flour blends showed to alter the functional properties. This study recommends composite flour 75:25 for processing semiliquid products like porridge due to reduced pasting properties values that may be associated with increased energy density compared to CF.
Removal of Hexane in Biofilters Packed with Perlite and a Peat–Perlite Mixture
(Kluwer Academic Publishers-Plenum Publishers, 2004-06) Kibazohi, Oscar; Yun, Soon-Il; Anderson, William A.
Removal of hexane from air–hexane mixtures in biofilters packed with different solid media under nitrogen supplementation was performed for 70 days. Two columns containing Perlite or a mixture of peat and Perlite, were used. The solid media were supplemented with nitrogen source up to 1 kg/m3 per week for high nutrient supplementation and 0.2 kg/m3 per month for low nutrient supplementation. A high rate of hexane removal: 95 g/m3 h was achieved under high nutrient supplementation, high air flow rate and high hexane concentration. However, the percentage of hexane removal decreased with increasing air flow rate and hexane inlet concentration. For high nutrient supplementation the type of solid medium did not significantly affect the biodegradation capacity. With low nutrient supplementation, the highest removal rate was achieved in the column containing the peat–perlite mixture. The column containing perlite had a significantly lower pressure drop (20 Pa/m) than the 2400–2930 Pa/m observed for the column containing the mixture. Perlite offers an opportunity of running a biofiltration process at a lower and stable pressure drop if the nutrient supplementation is managed properly.
Sensory profile, consumer acceptability and preference mapping of cassava-chia seeds composite porridges
(Elsevier, 2021-12-26) Katunzi-Kilewelaa, Ashura; Mongi, Richard; Kaale, Lillian D; Kibazohi, Oscar; Fortunatusa, Roman M; Rweyemamu, Leonard MP
This study applied quantitative descriptive analysis, hedonic test, and preference mapping techniques to inves- tigate the sensory profile, consumer acceptability, and drivers for consumer acceptability of cassava-chia seeds composite porridge samples. Chia seeds flour was developed and blended with cassava flour at varying propor- tions (0, 5, 10, 15, 20, and 25%) to make six composite porridges labelled CF, CCSF1, CCSF2, CCSF3, CCSF4, and CCSF5. The control cassava porridge (CF) formulation had significantly (p <0.05) higher sweetness and aroma intensities than the composite formulations. Conversely, the CCSF4 (20%) and CCSF5 (25%) composite formulations had significantly (p < 0.05) higher colour, mouthfeel, and oiliness intensities than the control for- mulation (CF). Furthermore, when compared to cassava porridge, the overall acceptability of composite porridge samples was significantly (p <0.05) much greater. Consumer preference for CCSF5 was much greater than for CF, although sample CCSF5 did not differ significantly (p > 0.05) from other composite porridge blends (sample CCSF1, CCSF3, and CCSF4). Consumer preferences for porridge formulations were largely driven by colour, tex- ture, and oiliness attributes. Thus, mixing up to 25% chia seeds flour with cassava flour produces a composite porridge with enhanced sensory properties and, hence, more consumer appeal than non-mixed cassava porridge. Significantly, this study creates an opportunity for small to large-scale food processors to valorise cassava flour by producing cassava-chia seeds composite flour to benefit the broader population in terms of food security and nutritional enhancement.
Vegetable oil production potential from Jatropha curcas, Croton megalocarpus, Aleurites moluccana, Moringa oleifera and Pachira glabra: Assessment of renewable energy resources for bio-energy production in Africa
(Elsevier, 2011-03) Kibazohi, Oscar; Sangwan, Rajbir S.
Research on vegetable oil for biofuels in Africa and Asia has focused mainly on Jatropha curcas while other potential oil bearing plants have received little attention. Vegetable oil production potential for five oil bearing plant species namely: Aleurites moluccana, Croton megalocarpus, Jatropha curcas, Moringa oleifera and Pachira glabra were investigated. Nuts and seeds of the plants were collected from the wild and their potential for vegetable oil production assessed in terms of seed/nut acreage yield, seed/nut oil content, harvesting requirement, and upstream processing before vegetable oil recovery. All five varieties were found to contain acceptable but different oil content ranging from 20 to 33% w/w, and seed/nut acreage yield of 3 t ha−1 y−1 to 12.5 t ha−1 y−1. Upstream processing was needed for A. moluccana to break open nuts to release the kernel, and dehulling for both C. megalocarpus and J. curcas to release the seeds, before extracting the vegetable oil, while the seeds of both M. oleifera and P. glabra did not need upstream processing. The Multi-criteria Decision Analysis ranked C. megalocarpus as the plant with the highest vegetable oil production potential of 1.8 t ha−1 y−1 followed by M. oleifera, J. curcas (1 t ha−1 y−1), A. moluccana, and P. glabra. The analysis underlines the need for more studies on C. megalocarpus and M. oleifera for biofuel production in Africa and other regions.

Browsing by Author "Kibazohi, Oscar"

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