Masters Degree Dissertations

Permanent URI for this collectionhttp://localhost:4000/handle/20.500.12504/107

Browse

Now showing 1 - 20 of 22

Antimicrobial, Growth, Acid and Aroma Properties of the Dominant Microflora Isolated at Different Stages of Gouda Cheese Production
(Kyambogo University [unpublished work], 2023-10) Namiiro, Josephine
The microflora of Gouda cheese is dominated by starter culture lactic acid bacteria (SLAB) and non-starter organisms, which are not deliberately added. Both of these groups of microorganisms are responsible for development of the cheese flavor and organoleptic properties during ripening. This study generally aimed to characterize the dominant microbial species at different stages of Gouda cheese production in order to identify non-starter bacterial strains with positive effects for possible application as starter culture adjuncts in fermented dairy matrices. Ten (10) independent samples from the Gouda cheese production line at Sanatos Dairies (U) Limited were collected at each of the following stages of production: raw milk, pasteurized milk, non-spiced Gouda cheese of one week, non-spiced Gouda cheese of one month, and spiced Gouda cheese of one month. The samples were enumerated within 8 h, for total viable counts (TVC), yeast and molds, total Lactococci, Staphylococcus spp., total coliforms/E. coli and total LAB using standard protocols. After enumeration of plates, colonies with different morphologies were purified (isolated) and examined for cell morphologies, Gram reaction and biochemical characteristics for presumptive identification and subsequently speciated the bacterial isolates using 16S rDNA sequence analysis. The dominant species were examined for genetic diversity using Unweighted Pair Group Method with Arithmetic Mean (UPGMA) clustering. Selected isolates from each of the major clusters were evaluated for antimicrobial activity, growth, acid and aroma production capacity in Ultra High Temperature (UHT) milk in order to prospect their possible application as starter culture adjuncts in fermented milk. LAB (2.34 - 7.77 log CFU/g) dominated the microflora of raw milk and cheese samples. TVC in respective samples corresponded with LAB counts implying that LAB were the major organisms in different samples examined. Of the 125 microbial isolates, 121 (96.8%) were found to be bacteria and were presumptively identified as Staphylococcus spp. (26.5%), Streptococcus, or Enterococcus (23.9%), Klebsiella, Enterobacter, Eschericia coli, Salmonella, Proteus, Serratia, or Yersinia (19%), Bacillus, Streptomyces, Listeria or Corynebacterium (9.9%) and Lactobacillus or Clostridium were 14.1%. 16S rDNA sequence analysis delineated 28 species with Lactococcus lactis (12.5%), Streptococcus lutetiensis (8.8%) and Lactobacillus plantarum (5%) being the major LAB species detected in all cheese samples; the rest of the isolates were either spoilage or pathogenic bacteria that could have found their way into the cheese post production. UPGMA clustering of these organisms associated them according to their different species and source of isolation; L. lactis from non-spiced Gouda cheese matured for one week were clustered together with L. lactis from spiced Gouda cheese matured for one month implying similar genetic relatedness. Each of the S. lutetiensis and L. plantarum clusters were only obtained from spiced Gouda cheese matured for one month. Thus, Lactococcus lactis and Lactobacillus plantarum were evaluated further for growth, antimicrobial activity against selected pathogenic bacterial strains, acid and aroma production properties. Single and mixed cultures of these organisms had similar growth patterns. All isolates inhibited E. coli, Salmonella and S. aureus on solid media assays but only one isolate of Lc. lactis (Gw-05) inhibited E. coli and Salmonella in the cell-free supernatant assay. In single culture, Lc. lactis had better acid production properties than Lb. plantarum. Mixed of these organisms enhanced acid production. During short term ripening, L. plantarum synthesized more organic acids, ketones, esters and aldehydes (13.7%, 2.3%, 9.3%, and 0.8%, respectively) than L. lactis which mostly produced organic acids and esters (38.7%, 6.6%, respectively). Co-culture of these organisms inhibited aroma production; only three organic acids and one ester were produced. During long term ripening, each of L. lactis and L. plantarum only produced organic acids and esters. However, L. plantarum produced more esters than L. lactis. Co-culture of the organisms enhanced aroma production resulting from synthesis of organic acids, esters and one ketone. It was therefore concluded that LAB dominate the microflora of Gouda cheese production. L. lactis has better prospects for application as primary starter culture in dairy products because they promote rapid acidification of milk, which is desirable for curd formation. Short-term fermentation of milk by single culture of L. lactis and L. plantarum enhance aroma production, while long term ripening enhances aroma production in mixed culture. Single cultures of these organisms could therefore enhance aroma formation in yoghurt, which requires short-term fermentation, whereas mixed culture could be applied in cheese, which requires long-term ripening.
Assessment of the cold chain capacity used in bulk handling of perishable agricultural produce in Uganda
(Kyambogo University [unpublished work], 2023-11) Abaasa, Paula
High food post-harvest losses negate the efforts geared towards improving food security and livelihoods of the population. There has been increased interest in addressing challenges associated with food post-harvest losses in policy circles, academia, and the private sector. Of the several mitigation measures suggested, investment in the food cold chain has been repeatedly pointed out as a solution to extensive postharvest losses worldwide, especially for perishable agricultural produce. This study assessed the cold chain capacity used in bulk handling of perishable agricultural produce (milk, meat, fish, fruits and vegetable) in the 16 cities of Uganda (Arua, Gulu, Jinja, Mbarara, Mbale, Masaka, Hoima, Entebbe, Lira, Kampala, Fort Portal, Kabale, Moroto, Nakasongola, Wakiso, and Soroti). Furthermore, the study monitored temperature and relative humidity management of the cold chain facilities and lastly assessed knowledge, attitude and practices of perishable produce retailers towards the cold chain. A total of 51 cold chain facilities used for bulk handling of perishable agricultural produce were found in 09 out of the 16 cities. These were spread out across the cities of Kampala, Wakiso, Mbarara, Fort Portal, Entebbe, Gulu, Masaka, Soroti and Jinja, with Kampala having the highest proportion (47.37%). The total bulk refrigerated storage space in the 16 cities was 39849.25 m3 serving a total ‘within city’ local population of about 8.8 million people which translates to a refrigerated storage capacity of 4.50 m3 per 1,000 inhabitants. The private sector owned the highest proportion (75.44%) of the cold chain facilities and only 21.05% were publicly owned. Generally, the temperatures of the cold chain facilities were not managed effectively as they varied significantly from the respective set point(s) of the cold rooms over the study period. Majority (51.4%) of the perishable produce retailers had no knowledge of the cold chain and 71.56% reported absence of nearby cold chain storage options. Therefore, there is inadequate refrigerated storage capacity for bulk handling of perishable agricultural produce in Uganda and this presents a need for investment in this sector by both public and private players. Cold chain operators need to actively monitor and manage the cold storage temperature and humidity. Interventions should target sensitization of perishable produce retailers on the paramount importance of cold chain management. These interventions will contribute to reduction of post-harvest losses in perishable agricultural produce.
Changes in aroma, pectin and physical properties of ripening cooking bananas
(Kyambogo University, 2019-11) Namakajjo, Richard Jonathan
Post-harvest losses are high in the cooking banana value chain in Uganda due to the short shelf life of the green bananas (6 to 10 days). The losses give rise to large amounts of solid wastes that later decompose into greenhouse gases that contribute to global warming. Hence, there is a need to add value to waste bananas by extracting bioactive substances such as aroma and pectin. In this study, changes in pulp and peel Colour, texture, fruit, pulp and peel weight, fruit, pulp and peel thickness and specific gravity were analysed during 0-12 days of ripening under ambient conditions. Pectin content was determined using acid extraction in combination with either ethanol or calcium chloride precipitation methods. Chemical properties of the pectin (ash content, methoxyl content, anhydrouronic acid and degree of esterification) were analyzed using Rangana’s protocol. Aroma compounds in the three ripening cooking banana cultivars, Nakitembe AAA-EA (NAK), Mpologoma AAA-EA (MPO) and Musakala AAA-EA (MUS) were analyzed using solid phase micro-extraction with gas chromatography flame ionization detection (SPME-GC-FID). Pectin extracted from the banana samples was used to formulate a pineapple jam containing different concentrations of banana pectin. The jam was evaluated for sensory acceptability using 30 untrained panelists. Colour significantly (p<0.05) changed from green to yellow in all cultivars with the peel showing more observable changes compared to pulp. There was significant decrease in hardness of all the selected bananas cultivars (p<0.05); Nakitembe 84.51 N to 9.76 N (88.45 % reduction), Musakala 80.48 N to 11.0 N (86.33 % reduction), Mpologoma 76.81 to 13.46 (82.48 % reduction). During the ripening period, hardness, fruit and peel weight, as well as fruit and peel thickness decreased significantly (p<0.05) and the extent of decrease was specific to a given banana cultivar. There was a significant increase in pulp to peel ratio for
Characterization of glucose syrup and ethanol from starch extracted from selected cassava and maize varieties grown in Uganda
(Kyambogo University [unpublished work], 2023-10) Bwamiki, Lydia
The research aimed to extract starch from the selected cassava and maize varieties, evaluate enzymatic and acid hydrolysis processes for glucose syrup production, and assess ethanol production. Characterization of the resulting glucose syrup and ethanol was also performed. A total of four (4) cassava varieties and four (4) maize varieties were used in this study. These included two local varieties of cassava (Mukumba and Mwezi mukaaga), two improved cassava varieties (TME 14 and NAROCASS 1), two open pollinated maize varieties (Longe 4H and Longe 5H) and two hybrid maize varieties (H 5355 and H 2115). Cassava was harvested at twelve (12) months while maize was harvested at four (4) months (120 days) after planting. Cassava and maize starch were extracted in three independent replicates using the wet and alkaline extraction methods, respectively. Glucose syrup was produced using acid and enzyme hydrolysis. Glucose syrups were fermented using Young’s dried active yeast (Saccharomyces cerevisiae) to obtain ethanol. There was no significant difference in the starch yield of the local and improved varieties for either cassava or maize. H 2115 produced the highest yield of 50.83% among the maize varieties while Mwezi mukaaga had the highest yield (29.1%) among the cassava varieties. Selection of the varieties for starch characterization was based on starch yield. Swelling power and solubility for all the starch varieties increased with increasing temperatures with Mwezi mukaaga having the highest swelling power (18.23 g/g) at 90°C and TME 14 having the highest solubility (2.45%) at 90°C. The content of amylose of cassava starch was higher than that of maize with Mwezi mukaaga having highest amylose content of 24.25%. Maize had higher resistant starch content than cassava with H2115 having the highest resistant starch content of 0.82%. The gelatinization temperatures for all starch varieties were not significantly different (p>0.05). Cassava varieties were much lighter than the maize varieties. The cassava starch granules were round, truncated with larger particle sizes (17.40 and 17.95 μm) as compared to the maize starch granules which were round, irregular and polygonal with smaller particle sizes (11.05 and 9.10 μm). Acid hydrolysis significantly produced higher (p>0.05) sugar concentration for both crop types as compared to enzyme hydrolysis. Among maize varieties, H 2115 had highest sugar content of 46.1 g/100 g (acid hydrolysis) and H 5355, 40.3 g/100 g (enzyme hydrolysis), while among cassava varieties, TME 14 had the highest sugar content of 31.2 g/100 g (acid hydrolysis) and Mukumba, 12.41 g/100 g (enzyme hydrolysis). Enzyme hydrolyzed samples showed highest sugar consumption by the yeast hence a higher alcohol (ABV) content and ultimately a better fermentation efficiency. Enzyme hydrolyzed glucose syrups had a higher ethanol content than the acid hydrolyzed syrups, with no difference between maize and cassava varieties in each treatment. These results propose that maize and cassava are good sources of starch, glucose syrup and ethanol with the maize varieties used in this study giving higher sugar concentrations than the cassava varieties.
Chemical composition of seeds from major passion fruit species: Passiflora edulis Sim,Passiflora eduli F flavicarpa and Passiflora maliformis grown in Uganda
(Kyambogo University(Unpublished work), 2021-03) Atuhwera, Agnes J.
Passion fruit (Passiflora spp.) seeds are usually discarded after extraction of the juice. The seeds, however, represent an important source of edible oil with a high proportion of polyunsaturated fatty acids and other vital components required for good health. The study determined the proximate composition, mineral content and fatty acid profile of the seeds of major passion fruit species (Passiflora edulis Sims, Passiflora edulis F.jlavicarpa and Passiflora maliformis L) grown in Uganda. In addition, stability tests including total carotenoids of oil extracted from these seeds were determined. Passion fruit seeds presented substantial amounts of oil, crude fibre and carbohydrates in the respective ranges of24.70±0.29 to 37.24±0.09%, 31.56±0.43 to 36.28±0.50% and 16.19±1.71 to 22.53±0.03% with significant differences at p~0.05. Crude ash content ranged from 1.36±0.10 to 2.32±0.01% with significant difference at p~0.05. The seeds had substantial amounts of proteins which ranged between 10.68±0.96 and 11.72±0.06% with no significant difference at p~0.05. Mineral composition analysed included Potassium (K), Sodium (Na), Calcium (Ca), Zinc (Zn), Copper (Cu), Iron (Fe), Selenium (Se) and Manganese (Mn) using AAS. The dominant mineral element was Potassium, highest in Passiflora ma/iformis L at 9.52±0.00 mg/l OOg and lowest at 4. 77±0.00mg/1 OOg in Passiflora edulis Sims followed by Fe, Zn, Ca, Cu, Se, Mn, then Na in their respective ranges of 2.32±0.008 to 5.98±0.002 mg/lOOg, 1.19±0.007 to 6.71±0.008 mg/lOOg, 1.45±0.035 to 2.01±0.033 mg/ lOOg, 1.34±0.006 to 1.94±0.001 mg/lOOg, 0.20±0.011 to 2.09±0.013 mg/lOOg, 0.77±0.008 to 1.82±0.001 mg/lOOg and 0.15±0.00 to 0.19±0.00 mg/OOg with significant differences at p~0.05. Passion fruit seed oil contained 14 detectable and quantifiable fatty acids including 4 major essential ones (linoleic acid, oleic acid, palmitic acid and stearic acid). The amount of linoleic acid and oleic acid were in the ranges of 67.57±0.85 to 72.18±0.86% and 14.59±0.17 to 16.41±0.21% of fatty acids, respectively with significant differences at p~0.05. Palmitic acid ranged between 8.68±0.1 1 and1 1.18±0.14%. Levels of Stearic acid were the lowest in the oil in the range of 2. 78±0.03 and 3.16±0.04% with significant differences at p~0.05. The unsaturated fatty acid content in oil was found to be high ranging from 85.68±0.98 to 87.60±0.15% with significant differences at p~0.05. Iodine values ranged from 125.25±0.04 to 135.35±0.02 g/lOOg of oil while saponification values ranged from 174.98±1.45 to 191.74± 1.32 mgKOH/g of oil with significant differences at p~0.05. The peroxide value was 0.10±0.00 meqOilkg in all species with no significant difference at p~0.05 . These results were within the recommended ranges by WHO and Codex standards for edible oils. Total carotenoids expressed as mg P-carotenoid/1 OOg of oil were significantly higher (p<0.05) m Passiflora edulis F.jlavicarpa with value of21.41±0.4 mg P-carotenoid/lOOg. In general, passion fruit seed oil contains substantial amounts of unsaturated fatty acids and is stable to peroxidation and can therefore be utilized in the human diet for health benefits .
Dietary diversity and nutritional status of learners in secondary schools of Kampala city, Uganda
(Kyambogo University, 2021-04) Tukahirwa, Patience
Introduction: The diet one takes is very fundamental for boosting and sustaining one’s health and nutrition’s needs especially when it is a balanced diet. Dietary diversity is vital for exposing the learners to different nutrients. Proper dietary diversity boosts education of learners and sustains their health and nutrition. The main objective of the study was to assess diet adequacy, nutritional status and nutrition and health education of learners in Kampala City, Uganda. Specifically, to assess the nutritional status determinants, establish the existing school menu options and adequacy of diet accessed by learners and to identify nutrition and health education activities emphasised in schools in Kampala City. Methodology: The study units included non-boarding secondary schools in the two divisions of Kampala Central and Kawempe. The study employed a cross-sectional design and descriptive in nature with qualitative and quantitative methods. The sample size of 240 respondents was selected. In addition, 24 key informants that is to say a head teacher and teacher responsible for nutrition matters were considered for the interviews from the 12 schools, 6 in each division. The study also employed multi-stage simple random sampling with three stages of sampling, criterion-based sampling and purposive sampling. Statistical analysis involved ANOVA techniques for finding mean differences while correlations were used for continuous variables at 0.05 statistical significance. The BMI z scores were got using WHO Anthro plus of 2007. Results: The mean (SD) age of learners was 15.6 (1.6), BMI Z-score 0.5 (1.1) and DDS 6.1(2.3). Majority of learners 80.5% had normal nutritional status: 11.7% underweight, 5.9% overweight and 1.9% obese. There was a strong significant correlation between age and BMI of learners (p < 0.001; r = 0.721) which implies that BMI increases with age of learners. There was a relationship between mean BMI and parental level of education (p = 0.001) and grade of learners (p = 0.031). Majority of the respondents 66.8% consumed 6 or more food groups. The most provided school foods included; mingled maize meal (posho), beans, rice, greens and maize porridge with meat, fish, groundnuts, maize on the cob and Green cooked banana (matooke) accessed within a week. All schools offered nutrition and health education activities the commonly offered being emergency preparedness, physical activity and fitness and counselling. Conclusion: It was established that majority of the learners had a normal nutritional status and it was positively associated with parental income source, grade and age of learners. Majority of the learners consumed 6 or more food groups and were getting lunch at school. This study findings have implications on public health nutrition and quality education. Where possible, there is need for improving nutritional sensitivity of meals provided by providing animal source foods that are rich sources of essential nutrients as part of the menu. Being an urban setting and given that one of every 10 learners assessed were in the overweight and obesity risk category, school-focused policy measures and guidelines promoting healthy school meals and food environments might be needed to check this problem from increasing among learners.
Effect of farmyard manure integrated with triple superphosphate on yield and grain quality of Biofortified common beans in central Uganda
(Kyambogo University, 2021-08) Wabusa, Derrick
A study was carried out to assess the effect of farmyard manure integrated with triple superphosphate on soil conditions, yield and grain quality of bio-fortified common bean Genotypes in central Uganda. The study evaluated the effect of different amendments of farmyard manure integrated with triple superphosphate (TSP) on soil conditions, yield components and grain quality of bio-fortified common bean genotypes. The experiments were set in a Randomized Complete Block Design (RCBD) conducted at Mukono Zonal Agricultural Research Institute (MUZARDI) in two rainfall seasons, where treatments included; Cattle manure + TSP, Swine manure + TSP, Chicken manure + TSP, TSP alone and control replicated five times. Bio-fortified common bean genotypes used in the study included Naro bean 1 and Naro bean 3, NABE16 a local check. Data was collected on; organic matter, soil pH, nitrogen, potassium and phosphorus content, harvest index, number of pods, pod length, number of grains per pod, weight of 100grains, grain yield, crude carbohydrates, fats, proteins, Iron and zinc content. Data collected was analyzed by a t-test for objective one and analysis of variance for objective two and three using Genstat statistical package (15th edition). Results showed that amendment of the soil with Swine manure + TSP significantly increased Organic matter by; 1.51% and potassium 1.22% than Chicken manure + TSP, Cattle + TSP, TSP alone and a control respectively. Chicken manure + TSP highly increased soil pH and Nitrogen by 1.80 and 2.20%, TSP alone improved Phosphorus by 5.2 PPM than other treatments. Yield parameters were not significantly (P>0.05) affected by treatments except weight of 100 grains. However bean genotypes grown in Swine manure + TSP recorded maximum yield of 14 pods, 4 grains per pod, 32.93g weight of 100grains, grain yield was (1843kgha-1) and lowest (1253 to 650kg/ha) in TSP+ cattle manure and control. Grain quality attributes were significantly (P<0.05) affected by all treatments however, swine manure + TSP was superior over other treatments on xiv grain quality of bio-fortified beans by 91.82% seed purity, 56.77%crude carbohydrates, 177.20 ppm Iron and 33.58 ppm Zinc content but, crude fats and crude proteins were higher in treatment TSP alone and Chicken manure + TSP. Bio-fortified bean Genotype Naro bean 1 significantly performed better than Naro bean 3 and Nabe 16. It was therefore, concluded that swine manure + TSP significantly improved soil conditions, yield and seed qualities of bio-fortified common beans. Therefore, basing on these findings, farmers should adopt amendment of swine manure with TSP
Evaluating the potential of pureed fresh green mature bananas as a functional ingredient for production of bread
(Kyambogo University(Unpublished work), 2021-08) Nankya, Norah
The nutritional value of green mature cooking bananas is mainly attributed to their resistant starch and dietary fibre content. This study aimed at developing bread using a composite mixture of wheat (70%) and pureed fresh green mature cooking bananas (30%) purposely to enhance its health benefits attributable to improved resistant starch and dietary fibre content, and to reduce postharvest banana losses which currently stand at 40% in Uganda. Eight treatments of wheat-banana composite bread were formulated as: (1) pureed fresh whole Mpologoma fingers, (2) pureed fresh Mpologoma pulp, (3) whole Mpologoma flour, (4) Mpologoma pulp flour, (5) pureed fresh whole N23 fingers, (6) pureed fresh N23 pulp, (7) whole N23 flour and (8) N23 pulp flour. Bread made from 100% wheat was used as the control. Alveograph and consistograph properties for each of the composite doughs were determined. Resultant bread was baked using the straight dough method, and analysed for physical attributes, as well as moisture, resistant starch and dietary fibre content using standard methods. All bread samples were assessed for sensory acceptability on a 9-point hedonic scale using 30 untrained panellists. The effect of addition of different forms (pureed fresh vs flour) and varieties of bananas on dough rheology and bread quality characteristics was evaluated by principal component analysis using XLSTAT software. Addition of pureed fresh and/or powdered bananas increased the mixing time required to reach maximum dough consistency. Mpologoma variety mostly increased the water absorption capacity of the composite mixture in pureed fresh and flour forms compared with other treatments, as it increased the amount of water needed for optimum dough production. Addition of bananas to wheat flour also reduced resistance to deformation (prmax) resulting in poor dough handling behaviour and low dough tolerance in the fermentation stage. Whereas all composite doughs generally had poor alveograph profiles suggesting low potential for using bananas in bread production, Mpologoma pureed fresh whole fingers had better rheological properties than all other composite samples highlighting its potential for application in the bread making process up to a (30%) substitution level. Additionally, dough samples containing bananas exhibited lower baking strength and resistance to mechanical mixing compared to the control indicating that the former were weaker doughs. The general appearance of bread obtained from banana-wheat composite doughs was appealing and comparable to that of the wheat alone control. High-quality bread was obtained from each of the treatments including pureed fresh or flour, whole fingers or pulp and different varieties which was contrary to alveographic and consistographic prediction data. Loaf volume ranged from 1137.97 cm3 to 14 10.00 cm3 in samples formulated from 30% N23 pureed fresh pulp and 30% N23 pureed fresh whole fingers, respectively. There was general increase in baking loss for bread formulated with banana flour compared with that made using pureed fresh bananas. Bread samples containing 30% Mpologoma pureed fresh pulp had the highest cross-sectional area while that from 30% N23 hybrid whole finger flour had the lowest. Loaf weight was highest in the 30% Mpologoma pulp flour (613.50 g), and lowest in the sample containing 30% N23 whole finger flour (544.00g). Crust and crumb browning increased with the addition of 30% bananas in comparison to the control. Composite bread exhibited reduced hardness, cohesiveness and adhesiveness compared to the control. Bread formulated using Mpologoma had highest moisture content while that made using N23 hybrid had the lowest. Overall, Mpologoma variety had higher contribution to resistant starch of the bread than the N23 hybrid, irrespective of pureed fresh or flour forms. Bread formulated from whole bananas had higher dietary fibre content than that made from banana pulp. Mpologoma whole fingers had the highest contribution to dietary fibre content of bread compared to all other treatments. Addition of bananas caused significant decrease in the sensory quality attributes of the composite breads compared to the control. Interestingly, bread made from 50% pureed fresh Mpologoma whole fingers was more appreciated for its general appearance close to that of the control. The blend of 30% Mpologoma pulp flour was most appreciated for colour. Bread texture generally hardened whereas flavour and taste decreased with the addition of bananas. It was therefore concluded that Mpologoma and N23 bananas could be added at a rate of 30-50% in pureed fresh or flour forms to formulate bread with high resistant starch and dietary fibre content. Addition of 30% banana pulp flour produced the best composite bread in terms of taste and flavour, irrespective of variety, and could have better prospects for commercial application compared with other treatments.
Farmers perception of the small East Africa zebu x Tyrolean grey cattle crosses performance in Uganda
(Kyambogo University, 2021-05) Acila, Goretti
The study aimed to determine the performance of the Small East African Zebu (SEAZ) and the Tyrolean Grey cattle crosses (TGX) in the selected cattle corridor districts (Kole, Nakapiripirit, and Kayunga of Uganda. SEAZ is an indigenous breed in Uganda, while the TG breed is indigenous to the alpine region of Austria and was introduced in the country through use of semen in 2009. Heart girth data collected for over three years at Lusenke Stock Farm (National Animal Genetic Resources Centre and Databank – NAGRC&DB) was used in the study. This study used cross-sectional survey design embracing qualitative and quantitative approaches. Data was obtained by use of structured questionnaires, focus group discussion, and Individual In-depth interview for farmers, AI technicians, farm managers and extension workers. The study revealed that, traits such as; better draft power (χ2=6.943, p<0.01) and resistance to parasites and diseases (χ2=4.477, p<0.05) were significantly associated with the SEAZ. On the other hand, docility (χ2=4.847, p<0.05), better milker (χ2=13.976, p<0.001), good mothering ability (χ2=10.174, p<0.001), fast growth (χ2=11.242, p<0.001) and hard hooves to withstand muddy places better (χ2=4.498, p<0.05), were significantly associated with the TGX. The study established that, the TGX were majorly and significantly constrained by parasites and diseases (χ2=7.967, p<0.05), shortage of feeds and grazing land (χ2=5.946, p<0.05), shortage of water (χ2=5.883, p<0.05), high prices of veterinary drugs (χ2=4.943, p<0.05), theft (χ2=5.385, p<0.05), and lack of AI services (χ2=13.507, p<0.001).Free range system was reported by the majority (81.6%). Pond/dam was the main water source reported by majority in the study (44.2%). Natural mating was the common breeding system used (45%). Greater proportion of the respondents (90.3%) reported problem of ticks in their farms. (52.5%) of the respondents reported no adaptation problem with TGX. Majority of the respondents reported AI technician as the major source of information about the cross breeding programme (56.7%). TGX was preferred by the majority of the respondents (78.8%).The study revealed that, there was a difference in the heart girth of the SEAZ and TGX (t=2.857, p<0.01). Based on the results of the study, the TGX showed better performance as compared to the SEAZ. At farm level, it is desirable for farmers to start keeping breeding records so that they can plan and control breeding for the future. The study recommends continued importation of TGX into Uganda to boost milk and meat production.The study aimed to determine the performance of the Small East African Zebu (SEAZ) and the Tyrolean Grey cattle crosses (TGX) in the selected cattle corridor districts (Kole, Nakapiripirit, and Kayunga of Uganda. SEAZ is an indigenous breed in Uganda, while the TG breed is indigenous to the alpine region of Austria and was introduced in the country through use of semen in 2009. Heart girth data collected for over three years at Lusenke Stock Farm (National Animal Genetic Resources Centre and Databank – NAGRC&DB) was used in the study. This study used cross-sectional survey design embracing qualitative and quantitative approaches. Data was obtained by use of structured questionnaires, focus group discussion, and Individual In-depth interview for farmers, AI technicians, farm managers and extension workers. The study revealed that, traits such as; better draft power (χ2=6.943, p<0.01) and resistance to parasites and diseases (χ2=4.477, p<0.05) were significantly associated with the SEAZ. On the other hand, docility (χ2=4.847, p<0.05), better milker (χ2=13.976, p<0.001), good mothering ability (χ2=10.174, p<0.001), fast growth (χ2=11.242, p<0.001) and hard hooves to withstand muddy places better (χ2=4.498, p<0.05), were significantly associated with the TGX. The study established that, the TGX were majorly and significantly constrained by parasites and diseases (χ2=7.967, p<0.05), shortage of feeds and grazing land (χ2=5.946, p<0.05), shortage of water (χ2=5.883, p<0.05), high prices of veterinary drugs (χ2=4.943, p<0.05), theft (χ2=5.385, p<0.05), and lack of AI services (χ2=13.507, p<0.001).Free range system was reported by the majority (81.6%). Pond/dam was the main water source reported by majority in the study (44.2%). Natural mating was the common breeding system used (45%). Greater proportion of the respondents (90.3%) reported problem of ticks in their farms. (52.5%) of the respondents reported no adaptation problem with TGX. Majority of the respondents reported AI technician as the major source of information about the cross breeding programme (56.7%). TGX was preferred by the majority of the respondents (78.8%).The study revealed that, there was a difference in the heart girth of the SEAZ and TGX (t=2.857, p<0.01). Based on the results of the study, the TGX showed better performance as compared to the SEAZ. At farm level, it is desirable for farmers to start keeping breeding records so that they can plan and control breeding for the future. The study recommends continued importation of TGX into Uganda to boost milk and meat production.
Fatty acid composition of oils from green coffee beans from different agro-ecological zones of Uganda
(Kyambogo University(Unpublished work), 2018-11) Mugabe, Amos
Coffee is an important agricultural commodity and beverage widely consumed throughout the world. Two-thirds of Ugandans depend on coffee as an important source of income. The quality of coffee determines the relative price and its end use. The lipid composition has been used to characterize Arabica and Robusta coffee. Oil yield, fatty acid (FA) composition and oil nutritional quality of green coffee beans; arabica coffee (Coffea arabica) from Bugisu, Rwenzori, Kisoro and Maracha, and robusta coffee (Coffea canephora var. robusta) from Iganga, Ibanda, Rukungiri, Mbarara, Ntungamo, Masaka, Kayunga and Luwero coffee regions of Uganda were determined. Green coffee beans were obtained from Uganda Coffee Development Authority (UCDA) and coffee dealers in Iganga, Luwero, Kisoro and Maracha Districts. Oil was extracted in a Soxhlet apparatus using n-hexane. Fatty acids were determined as the FA methyl esters (FAME) using flame ionization detection gas chromatography. Differences in oil yield were analysed by ANOV A. The PUF A/SaF A, MUF A/SaF A, (PUF A +MUF A)/SaF A and PUF A/MUF A ratios were used to evaluate the nutritional quality of the oil. Oil yield ranged between 1. 75 and 15 .45%. Arabica coffee from Bugisu gave a significantly (p < 0.05) higher oil yield. Robusta coffee from Ntungamo gave the lowest mean oil yield. Unsaturated fatty acids (UFA) predominated over saturated fatty acids (SaFA). Linoleic and oleic acids were the main unsaturated fatty acids accounting for 53% of the total. Palmitic acid was the major SaFA. Oil yield and FA composition were dependent on agro-ecological coffee sample source and coffee variety. Based on the obtained nutritional quality indices, green coffee oil can be used in foods on blending with other oils. Nevertheless, there is need to investigate the existence of the transfatty acids in green coffee oil. KEY WORDS: Coffea arabica, Coffea canephora, fatty acid, green coffee beans, oil yield
Formulation of an iron biofortified bean-silverfish instant sauce for pregnant women
(Kyambogo University[unpublished work], 2022-07) Musabi, Diana
In Uganda, there is an increasing burden of anaemia especially among pregnant women and children aged 6-59 months. Some of the readily available and affordable food to pregnant mothers are beans which have relative amounts of iron but also high levels of phytates which reduce Fe bioavailability. Bio-fortification of beans enhances their iron content which is further complemented with the iron in the silver fish. This study aimed at developing a safe and acceptable iron biofortified bean - silver fish composite sauce to prevent anaemia among pregnant women through improved micronutrient intake. Design expert software was used to generate four composite formulations of iron biofortified bean-silver fish in the ratios of 90:10, 80:20, 70:30 and 100:0, respectively, each contributing more than 70% Recommended Daily Allowance of iron for pregnant women of reproductive age. Commonly used seasonings and spices (tomatoes, garlic, onions and Mchuzi mix) were added in equal proportions to each of the composite formulations. The instant composite flour was produced using extrusion technology and analysed for moisture, crude protein, crude oil, crude ash, carbohydrates, selected minerals, folate, total phytates and aflatoxin levels. Microbiological analysis considered total plate counts, total coliforms, Escherichia coli, yeast and moulds, Salmonella and Staphylococcus aureus. The composite flour was reconstituted into instant sauce with boiling water and evaluated for sensory properties using a panel of 50 semi-trained analysts. Extrusion of iron bio-fortified beans-silverfish instant sauce with the ratio of 80:20 had increased moisture content from 5.84 to 10.33% compared to the raw un-extruded beans. Fortification of extruded NABE beans composited with silverfish (NABE 1 (90:10); NABE 5C (70:30); NABE 5C (100:0); NABE 1 (70:30); NABE 1 (80:20), respectively) increased the iron, calcium, zinc, magnesium and folic acid content from 41 to 336 mg/kg, 447 to 15214 mg/kg, 36 to 276 mg/kg, 875 to 1113 mg/kg, and 7.75 to 47.47 mg/kg, respectively compared to the non-fortified raw beans. The treatments reduced total phytate content from 17.36 mg/g in raw beans to 12.92 mg/g in the extruded product. The iron bio-fortified beans – silverfish composite instant sauce had low levels of total aflatoxin, aflatoxin B1 and aflatoxin B2, and undetectable levels of Salmonella spp., E. coli, and Staphylococcus aureus indicating that the product is safe for human consumption. Addition of silver fish to the beans enhanced the sensory acceptability of the instant sauce with the sample containing NABE 5C (80:20) being the most preferred overall (p>0.05). From the findings, it was shown that addition of silver fish increases the nutrient content of an iron bio-fortified beans – silverfish instant composite sauce. The addition of silver fish also increases iron and folic acid content of the product and could therefore, reduce cases of anaemia among pregnant mothers. It was recommended that consumption of about 50g per serving of the instant sauce (80:20) twice a day can complement the iron-folic acid (IFA) from the diet as well as IFA supplements given out at antenatal centres to meet the recommended daily allowances for these micronutrients in pregnant women of reproductive age.
Health risks associated with heavy metal exposure in geophagic products (Emumbwa) consumed during pregnancy
(Kyambogo University, 2021-06) Nabuuma, Justine
Geophagic products (Emumbwa) consumed by some pregnant women in Uganda may be a source of heavy metal poisoning. However, there is paucity of information regarding the composition, safety and consumption patterns of these products. This study aimed to assess the levels of heavy metals; lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), copper (Cu), chromium (Cr), nickel (Ni), manganese (Mn) and zinc (Zn), and the health risks due to Pb, As, Cr and Ni in geophagic products consumed by pregnant women in Kampala city and the surrounding areas. A total of 60 geophagic clay samples obtained from five markets in Kampala city, were analyzed for the 10 elements using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Geophagic products consumption patterns of 280 pregnant women (18 to 60 years of age) were determined using a set of pre-tested questionnaires. Means were separated by two-way analysis of variance (ANOVA) using XLSTAT, version 2020. Health risk assessment was done using Chi square statistics of the Microsoft Excel in built @risk software (Version 8.1, USA). Iron had the highest concentration (1500 to 22900 mg/kg) followed by Mn (0.68 to 8.99 mg/kg), Zn (0.48 to 2.44 mg/kg), Cr (0.51 to 1.57 mg/kg), Cu (0.14 to 1.20 mg/kg), Pb (0.29 to 0.66 mg/kg), Ni (0.08 to 0.39 mg/kg) and Cd (0.02 to 0.06 mg/kg). Mercury and As were not detected in any of the samples of Emumbwa analyzed. Most respondents were 35 to 54 yrs and had body weight between 60 and 80 kg. The majority (83.81%) earned less than one million Uganda shillings per month. The mean clay ingestion rate was 17.08±7.32 g per day. According to this study findings, both consumers and the total population are at a risk of developing chronic kidney disease, combined adenomas and carcinomas and post implantation fetal loss due to lead, chromium and nickel exposure. While geophagia can contribute significantly towards the intakes of useful elements such as Fe, Cu and Zn, the practice poses potential health risks to the consumers due to Pb, Mn, Cd, Ni and Cr poisoning. Sensitization of the population by health workers about the potential health risks of heavy metals in geophagic products is recommended. Key words: Heavy metal, Emumbwa, geophagia, health risk, risk assessment, consumption pattern.
Levels of antibiotic residues in cow's milk sold in commercial centers of Kampala city
(Kyambogo University (unpublished work), 2018-05) Namutebi, Eva
Veterinary drug residues in milk represent a health risk for the consumer especially young children. Prolonged exposure to antimicrobial residues in food and milk may lead to antimicrobial resistance and other health problems. The objective of this study was to evaluate the types of antibiotic residues and their levels in milk, and the health risks posed to milk consumers in Kampala City. A total of one hundred twenty five samples (25 processed and l 00 raw) were randomly obtained from different commercial points in Kampala. The milk was analyzed for quinolone, tetracycline, aminoglycoside, sulfonamide, amphenicol and 13-lactarn groups of antibiotics using liquid chromatography tandem mass spectrometry (LC/MS/MS). Residue levels of antibiotics in processed milk were in the range of; not detected to 0.0472 μg/l, not detected to 0.0056 μg/1, 1.2231 to 32.3927 μg/l, 1.8836 to 25.4283 μg/l, 0.0001 to 0.0006 μg/1, 0.0143 to 0.113 μg/l for quinolone, tetracycline, aminoglycoside, sulfonamide, amphenicol and 13-lactam, respectively. The corresponding levels in raw milk ranged from not detected to 0.0309 μg/1, not detected to 0.0309 μg/1, 1.1795 to 31.351 μg/l, 1.6698 to 38.2626 μg/l, not detected to 0.0004 μg/1 and not detected to 0.5109 μg/l. Levels of aminoglycoside were generally high compared to other groups of antibiotics in milk. However, drug residue levels were in all cases below the maximum residue limit (MRL) according to Food and Agriculture Organization (FAO) and United States Food and Drug Administration (USFDA). Based on the observed levels of antibiotics, processed and raw milk in Kampala is safe for human consumption. Nevertheless, regular monitoring of antibiotic residues in milk is recommended.
Non-cancer health risks associated with pesticide residues and heavy metal exposures in locally manufactured cereal-based baby foods in Kampala city
(Kyambogo University, 2019-11) Nantongo, Sarah
Pesticides residues and heavy metals are major environmental pollutants and their toxicity is a problem of increasing significance for nutritional and environmental reasons. Data on the risk contribution of heavy metal contaminated cereal-based baby foods towards the disease burden in Uganda is inadequate. The study therefore assessed the awareness of exposure to pesticides, and heavy metals (HM) among manufacturers of baby foods, detected organochlorines and organophosphorus pesticides, determined the levels of selected HM (lead, cadmium, Arsenic, and mercury) and the non-cancer risks posed by these contaminants in cereal-based baby foods produced in Uganda. A set of pretested questionnaires was used to assess the level of pesticide and heavy metal responsiveness among manufacturers (n= 16) of baby foods. Samples of baby foods (n= 18) obtained from supermarkets, retail shops and groceries around Kampala City were analysed for organochlorines, organophosphate pesticides, and the heavy metals (As, Hg, Cd and Pb). Maximum levels of HM detected were 0.016 mg/kg, 0.016 mg/kg, 0.030 mg/kg, and 0.037 mg/kg for Pb, Cd, As, and Hg respectively. Pesticide residues were identified using Gas Chromatography coupled with Mass Spectrometry (GC/MS). Heavy metal concentration was determined using Atomic Absorption Spectrophotometry (AAS). Non-cancer risk posed to babies through heavy metal exposure in baby foods were determined for infants aged 6 to 24 months using the non-cancer hazard quotient (HQ) described by the United State Environmental Protection Agency (US EPA). The organochlorine 4, 4-Diphenyl DichloroTrichloro ethane (DDT) was the predominant pesticide detected in 88.8% of the baby foods tested. The concentration of As in baby foods ranged from 0.010 to 0.030 mg/kg, Hg content ranged from 0.003 to 0.037. The range concentration for Cd and Pb were 0.002 to 0.150 and 0.001 to 0.016 mg/kg, respectively The hazard quotient of heavy metals in cereal based baby foods for infants was below 1 for Pb, Cd and Hg but was greater than 1 for As, indicating potential risk to the infants for As. Hazard index values of the heavy metals were above 1 for all baby foods. The non-cancer risk due to heavy metal exposure in locally manufactured baby foods in Kampala was unacceptable. Therefore, regular monitoring of baby foods for chemical contaminants is recommended to ensure safety.
Non-cancer risks and mitigation strategies of fe, mn, cu and cr in milled maize flour
(Kyambogo University, 2021-08) Ainebyona, Denis
In Uganda, maize (Zea mays), is milled into flour that is used as an ingredient in many food products including baby foods. Milling is mainly done in hammer mills that are fabricated using mild steel. Mild steel is made up of iron (Fe), manganese (Mn), copper (Cu) and chromium (Cr) as the major heavy metals (HM). During milling, hammer mill parts wear out and release metal particles into the flour. Heavy metals are a risk factor for chronic illnesses such as cancer, diabetes and heart disease. The safety of maize flour with regard to HM contamination arising from milling operations in Uganda is not known. This study aimed assessed the non-cancer risk and mitigation strategies to minimize Fe, Cu, Cr and Mn exposure in maize flour. A total of fifty samples (25 maize grain and 25 maize flour) were obtained from 5 milling enterprises in Kampala city. Metal concentration was determined using Atomic Absorption Spectrophotometry (AAS). Non-cancer risks due to HM exposure were determined using the non-cancer hazard quotient (HQ) and hazard index (HI) described by the United States Environmental Protection Agency (US EPA). Multi-Criteria Decision Analysis (MCDA) using Promethee-Gaia software 1.4 Academic Edition was used to determine the best risk management option. Data was analyzed with A General Linear model using SPSS for Windows, Version 16.0 (2007), SPSS Inc, Chicago, IL, USA. Milled flour samples had significantly (p < 0.05) higher concentrations of HM than the grain. Heavy metal concentration ranged from 0.257 to 1.782, 0.016 to 0.198, 0.122 to 0.501 and not detected (ND) to 1.151 mg/kg for Fe, Cu, Cr and Mn, respectively. The HQ and HI values were less than the United States Environment Protection Agency (US EPA) management level of 1 for both children and adults. Consumers of maize flour produced in hammer mills in Kampala will not experience adverse health effects. Nevertheless, the bioaccumulation of HM in the body organs poses a danger. Therefore, the possible development of risk should be monitored on a regular basis with the view of putting in place measures to protect public health.
Nutritional quality of pumpkin (Cucurbita Pepo L.) Seeds based on the mineral and fatty acid composition
(Kyambogo University, 2019-10) Akwap, Pamela
Pumpkin seeds contribute to the nutrition of human populations and are also used in medicine in many parts of the world. In Uganda, pumpkin seeds are nowadays promoted and consumed as a snack. The potential of a food to be recommended for human consumption is determined primarily by the composition of its nutrients. The probable contribution of pumpkin seed towards the mineral, and essential fatty acid and total dietary lipid intakes in Uganda is not well known. The objective of this study was to determine the mineral content and oil yield of pumpkin seeds, analyze the fatty acid composition, and assess the nutritional quality of the lipid fraction. Mineral content was determined using atomic absorption spectrophotometry (AAS). Fatty acid composition was determined using gas chromatography with flame ionization detection (GC-FID). Nutritional quality was determined using total polyunsaturated fatty acid (PUFA)/total saturated fatty acid (SFA), ω6/ω3 and hypocholesterolemic /hypercholesterolemic (h/H) ratios, and the atherogenicity (AI) and thrombogenicity indices. Potassium (K) and magnesium (Mg) were the major macro-elements with mean concentrations of 416.45±27.66 and 407.56±58.93 mg/kg, respectively. Iron (Fe; 7.56±0.68 mg/kg) and zinc (Zn; 5.57±0.65 mg/kg) were major microelements. The oil yield ranged from 9.73% to 40.81%. The predominant fatty acids in decreasing order were linoleic (C18:2ω6), palmitic (C16:0), oleic (C18:1ω9) and stearic (C18:0) acids. Low linolenic acid levels (C18:3ω3; < 1%) were observed. The PUFA/SFA and h/H ratios, and the values of AI and TI as 0.23 and 0.90 repetitively for the pumpkin seeds were favorable. Pumpkin seeds are a health food for human consumption. KEY WORDS: Cucurbita pepo L., mineral, oil yield, fatty acid, AI, TI, h/H ratio. 1 CHAPTER 1:
Optimisation of the quality of bread from wheat, banana and cassava composite flour
(Kyambogo University(Unpublished work), 2018-10) Nakisozi, Henriettah
Bananas and cassava are important staple foods in terms of caloric intake in Uganda. These traditional crops are highly perishable with little value addition. This study examined the prospects of application of banana, cassava and wheat composite flour in the development of bread. Sixteen composite flour blends were prepared using D-optimal constrained mixture design within a range of 40 to 80% for wheat, 10 to 30% for cassava and 10 to 30% for banana. Nutrient quality and sensory acceptability of the breads were optimized using design expert software. Baseline assessment on bread consumption was conducted from Kampala city. Information on bread consumption and purchasing behaviour was collected using a questionnaire. Banana (EAHB) cultivar cassava (NASE 19) and wheat were used for bread development. Moisture was analyzed using hot air oven (BTI-29, India), dry ashing for ash using a muffle furnace (FSL 340-0 I 00, Gallenkamp, UK), Kjeldahl method for crude protein, Soxhlet method for crude fat and Gravimetric method for crude fiber. Total carbohydrate content of bread was determined by difference method. Loaf weight and loaf volume were evaluated using a digital laboratory scale (CE-4101, China) and rapeseed displacement method, respectively. Bread firmness was determined using a TA XTplus texture analyzer (Stable Micro Systems, Gudaiming, Surrey, UK). Sensory attributes (taste. odor, color, texture and overall acceptability) were evaluated on a five-point hedonic scale. Bread consumption was high (66.4%) amongst young people. A large (37. l %) proportion of the population consumed bread daily and sweet bread was mostly (88.2%) liked. Over 70% of respondents preferred white bread to whole meal bread. Large companies (56. l %) were the main purchasing points because bread was considered to be fresh. Freshness (36.4%) was the most important criteria for preference of bread. Blending had a significant effect on carbohydrate, protein, ash, loaf volume, taste and odor (p<0.05). Banana addition increased mineral amounts in bread whereas cassava increased total carbohydrate. The optimum blending ratio for both nutritional and sensory acceptability was in the range of 71.2% wheat, 10.6% cassava and 18.2% banana flours. Loaf volume ranged between 803.3 and 13 l0cm3. Loaf volume of bread processed from less than 70% wheat flour was inferior. Crumb firmness values ranged from 6.4 to 29.8 N. Bread developed from 50% wheat, 40% banana and 10% cassava had the highest (29.8 N) firmness whereas that made from 80% wheat, 10% banana and l 0% cassava had the lowest (6.4 ) firmness. It was concluded that controlled processing of banana and cassava flours, maintaining wheat flour around 70% and high proportion of banana flour (about 17%) in the blend, would lead to production of high quality bread with high content of minerals and bioactive compounds such as polyphenols, flavonoids etc. Bread from banana, cassava and wheat was of good quality to consumers.
Potential of spontaneous microbial fermentation isolates to improve fermentation and cup quality of wet processed Arabica coffee (coffea arabica)
(Kyambogo University, 2021-07) Mugerwa, Fredrick
Spontaneous wet processing of coffee currently practiced in Uganda is constrained by long processing times, losses, and inferior quality coffees. Starter cultures are nowadays used to control fermentation of foods. This study evaluated the predominant yeasts and bacteria in the spontaneous fermentation of Arabica coffee (Coffea arabica) from Bugisu and their potential use as starter cultures in the wet fermentation of coffee. A total of 21 samples of the fermenting mass of Arabica coffee (100 ml each) were used for isolation of predominant yeasts and bacteria during spontaneous fermentation. The isolates were grouped by cell morphology and biochemical features and then subjected to polymerase reaction (PCR) for confirmation of species. Genomic DNA of the organisms was extracted and the variable region 3 of 5.8S and 16S rRNA genes for yeast and bacteria respectively were amplified PCR using universal primers ITS1 and ITS4, and P16S and M26S, respectively. Representative isolates from each PCR profile were identified by sequencing using Sanger sequencing and the closest known relatives of the sequences obtained were retrieved from the National Centre for Biotechnology Information data base using a Basic Local Alignment Search Tool (BLAST). The predominant microorganisms were enriched and their effects on the fermentation process were determined. Controlled fermentation of pulped Arabica coffee (100 kg) was carried out. Physicochemical changes namely pectin, total soluble sugars, viscosity, hydrogen potential and titratable acidity were monitored in the fermenting mass using standard AOAC and ISO methods. Coffee beans from the controlled fermentation experiments were roasted at 210oC for 10 min, to medium dark roast profile and evaluated for the cup quality using the Specialty Coffee Association (SCA) cupping protocol. The yeasts Kazachstania exigua and Pichia kudriavzevii, and the bacteria Leuconostoc mesenteroides and Paenibacillus campinasensi were the predominant spp. in the in the spontaneous fermentation of C. arabica in Bugisu sub region. Mixed cultures performed better than single cultures in promoting fermentation.
Probiotic, starter culture and antimicrobal properties of lactic acid bacteria isolated from Ugandan traditional ghee
(Kyambogo University(Unpublished work), 2021-08) Abbo, Immaculate
Ghee is one of the major fermented foods consumed in Uganda despite the fact that it is largely produced traditionally raising issues of quality control and assurance. This study investigated the bacterial diversity of traditional ghee obtained from different regions of Uganda in an effort to determine the technological properties of its dominant lactic acid bacterial (LAB) flora. A total of nine samples were purchased in original packaging, from Buganda (2), Bunyoro (2), Teso (2) & Ankole (2) regions including a control sample and subjected to microbial analysis using conventional and molecular protocols to obtain an overview of the microbial diversity of these different ghee varieties in order to focus on the dominant LAB flora. Traditional ghee from Teso was contaminated with coliforms and E. coli, but the latter were not isolated which could be due to failure to collect these organisms from random colonies selected from the media plates during isolation. The species identified using 16S rDNA sequence analysis include Enterococcus faecium (22 isolates, 30%), Lactobacillus plantarum (20 isolates, 28%), Lactobacillus rhamnosus (11 isolates, 15%), Enterococcus hirae (11 isolates, 15%), Enterococcus faecalis (2 isolates, 3%) and Bacillus cereus (2 isolates, 3%), with Lactobacillus spp. being the dominant (31 isolates, 43%) genus detected in all samples. MEGA X analysis of the 16S rDNA PCR gel images gave separate clusters for each of L. plantarum and L. rhamnosus; each of the clusters was heterogeneous and contained isolates from different subregions of Uganda highlighting possible genetic relationship between these Lactobacillus isolates. Since L. rhamnosus is preferred to L. plantarum for inclusion in fermented dairy products due to its probiotic properties, three (03) L. rhamnosus isolates were evaluated for potential probiotic properties, antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Salmonella enterica, and growth and acid production profiles in milk, in order to establish their prospects for application as probiotics, bio-preservatives and/or starter cultures in milk and other fermented foods. Each of the tested isolates exhibited good acid tolerance at the exposure of 0.7% ox bile at 30ºC for 0, 3, 6 and 9 h and remained viable (3 log reduction) after 3 h of exposure at pH 3, did not produce biogenic amines and had high level of auto-aggregation at 24 h. However, all the isolates were sensitive to bile salts implying that they may not survive the xii entire gut transit. On agar overlay assays, each of the L. rhamnosus isolates had antimicrobial activity against at all the tested indicator bacteria at 30oC, 24 h and 37oC, 24 h for LAB isolates and indicator bacterial strains, respectively. In the disc diffusion assays, only neutralized cellfree supernatants for each of the Lactobacillus isolates lost antimicrobial activity, implying that activity was due to acid production. Subsequently, two L. rhamnosus isolates were studied further for growth kinetics and acid production prospects in UHT milk model to determine their starter culture potential. All the L. rhamnosus isolates had similar growth patterns in milk attaining 8-10 log cfu/ml at 48 h. However, the isolates had low acid production capacity leading to a pH decrease from 6.89-6.92 to 4.89-5.04 after 48 h of fermentation. Acid production was growth-dependent and maximum acidification occurred at exponential phase (8-24 h). It was concluded that L. rhamnosus isolated from Ugandan traditional ghee does not have prospects for application as a starter culture due to its low acidification capability. However, these organisms have some favorable probiotic and antimicrobial properties which could be exploited commercially. Further research should investigate the aroma compounds which could be produced by these organisms in milk and other fermented foods when grown alone and in coculture with L. plantarum, and/or yeasts and moulds which were also detected in the traditional Ugandan ghee. Further studies should focus on stabilization of the lactic acid bacterial isolates against bile
Proximate composition, metal, polyphenol and flavonoid contents of green and black tea in Kampala
(Kyambogo University [unpublished work], 2023-06) Odur, Denis
Uganda is the second leading producer of tea in Africa. However, there are quality and safety concerns of Uganda's tea in the international market. This study determined the proximate composition, the essential and toxic elements, and total polyphenols and flavonoids in green and black tea from selected supermarkets in Kampala. Proximate analysis (moisture, ash content, protein, fat, and carbohydrate) was done as per the procedures of the Association of Official Analytical Chemists (AOAC). Essential elements; sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), manganese (Mn) and iron (Fe), and nonessential elements; mercury (Hg), lead (Pb), cadmium (Cd), arsenic (As), were determined using atomic absorption spectrophotometry (AAS). Total polyphenol and flavonoid contents were determined following the Folin-Ciocalteu method and aluminum chloride using colorimetric assay, respectively. Moisture, fat, protein, ash, crude fiber and carbohydrate levels in the tea ranged from 2.64 to 8.43, 0.87 to 3.74, 12.41 to 29.28, 4.34 to 9.08, 12.12 to 31.46 and 28.65 to 61.13 %, respectively. Lead, As, Cd and Hg were not detected in all samples. Metal concentrations were in the range of 694.95 to 2681.83, 4.53 to 11.77, 17.51 to32.59, 47.60 to 141.17, 39.77 to 280.94, 1.18 to 2.28 and 8.30 to 37.69 mg/kg correspondingly for K, Na, Mg, Mn, Ca, Cu and Fe. The total polyphenol and flavonoid amounts ranged from 82.17 to 159.31 mg GAE/g DW and 122.12 to 183.24 mg RE/g DW, respectively. Moisture and ash contents of the green and black tea were within recommended limits. Tea in Kampala is generally safe for human consumption because of the low levels of toxic elements. The high levels of polyphenols and minerals observed in green tea imply that green tea can be an additional source of these components in the diet. Therefore, drinking green tea may be more beneficial than drinking black tea for consumer.

Browse

Browsing Masters Degree Dissertations by Title