Masters Degree Dissertations

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Dough rheology and baking properties of bread from wheat/ hybrid banana composite flour
(Kyambogo University (Unpublished work), 2024-02) Kimera, Baker
In spite of high productivity and good agronomic adoptability of hybrid cooking bananas, they have undesirable sensory characteristics hence low consumer acceptability. This study aimed at evaluating the effect of partial substitution of wheat with hybrid cooking banana flour on the dough rheology and baking properties of composite bread. Five hybrid banana varieties; M30, M9, N15, N21 and N23 were used in this study. Bananas at green maturity were processed into flour and blended with wheat to make various composite flours (10/90, 20/80, 30/70 and 40/60%). Unblended wheat flour (100%) was used as a control. The different blends were then used to make the wheat composite bread using the straight-dough method. Rheological properties of the composite dough were analyzed using a consistograph (water absorption capacity and maximum pressure), alveograph (peak height, extensibility and baking strength) and farinograph (mixing tolerance index and development time). Textural properties (hardness, springiness, cohesiveness) were determined using the texture analyzer while sensory attributes were investigated using the 9-point hedonic scale. The dough rheology values reported in this study ranged from; water absorption capacity (47.25% to 54.45%), maximum pressure (1315.50 mbar to 2911.50 mbar), peak height (82.50 mm to 151.50 mm), extensibility (19.50 mm to 113.50 mm), baking strength (67.50 J to 244.50 J), development time (1.10 min to 5.40 min) and mixing tolerance index (86.00 BU to 175.50 BU). Hardness increased with increasing banana flour percentage inclusions, ranging from 2.09 N to 4.39 N. Springiness had no specific trend across the hybrids, but ranged from 0.35 to 0.80. Cohesiveness decreased with an increase in banana flour inclusion levels, ranging from 0.05 to 0.56. Sensory evaluation results showed a decrease in panel acceptability of the composite bread as the percentage inclusion of hybrid banana flour increased. The best scores for the sensory parameters evaluated were recorded at 10% inclusions of M30. Inclusion of hybrid banana flour up to 10% for all varieties studied as well as 20% inclusions for M30, N21 and N15 was comparable to 100% wheat flour. It is therefore recommended to use up to 20% inclusion levels of hybrid cooking banana flour from M30, N21 and N15 in preparation of hybrid banana / wheat composite bread.
Contribution of selected ingredients to the quality of wheat/unpeeled orange fleshed sweet potato puree composite bread
(Kyambogo University (Unpublished work), 2024-02) Skaka, Vitalis
The development of bread from composite formulations is increasing and has attracted much attention from researchers driven by the desire to find non-wheat-bread-making alternatives in order to reduce dependence on imported wheat. However, formulation and production of acceptable composite bread requires understanding the effects of ingredients on bread quality. this study aimed at assessing the contribution of selected ingredients to the quality of composite dough made from wheat flour and unpeeled orange-fleshed sweet potato (OFSP) puree as well as physical qualities, nutritional composition, and consumer acceptability of the resultant bread. A 2-level fractional factorial design (28-3) at resolution IV was used to design a screening experiment and Response Surface Methodology (RSM) was used to analyze data. Prmax and water Absorption of the composite dough were studied using the alveoconsistograph. Physical properties and nutritional composition of composite bread were analyzed using AACC, AOAC and ICC standard methods. Consumer acceptability was assessed by an untrained panel of evaluators using a 9-point Hedonic scale. Significant models were developed at p<0.05 and coefficient of determination, R2 was used to test fitness of the model terms. Prmax and Water absorption decreased as proportions of unpeeled OFSP puree increased from 20% to 50%. Proportion of unpeeled OFSP puree negatively affected crumb colour, specific volume, springiness, flavour, aroma and general acceptability but had a positive effect on weight, moisture content, Total carotenoid content, β-carotene content, vitamin A content, reducing sugar content, protein content, Amylose and amylopectin ratio and starch content. Yeast positively affected volume and crust colour with negative effect on baking loss, staling rate, firmness and chewiness. Treatment of unpeeled OFSP (pasteurized and unpasteurized/fresh) negatively affected texture. Variety had a significant effect on crude fiber with NASPOT13O having a negative effect and NKB135 exhibiting a positive effect. Fat negatively affected cohesiveness. Ascorbic acid (improver) had the least effect on the study responses. Principal component Analysis indicated a negative correlation between nutritional and sensory properties. a positive correlation between textural properties and sensory properties and a high correlation between physical and sensory properties of the bread were observed. The study concluded that the most significant among the selected ingredients that affected quality of wheat/unpeeled OFSP puree bread were proportion of puree, yeast and fat. The study also concluded that treatment and variety had significant effects on the quality of the composite bread.
Effect of 1-methylcyclopropene treatment on the physico-chemical attributes and postharvest green life of Ugandan indigenous and hybrid cooking bananas
(Kyambogo University (Unpublished work), 2024-02) Kisakye, Sarah
In this study, the efficacy of 1-methylcyclopropene (1-MCP), an ethylene inhibitor was evaluated in extending the green life of harvested mature green East African Highland (EAH) bananas including hybrid cooking bananas (Matooke). The main objective was to lengthen the green life of the EAH cooking bananas while maintaining physico-chemical and sensory properties. Five cooking banana varieties, two indigenous (Mpologoma and Nfuuka), and three hybrids (NARITA 2, NARITA 4 and NARITA 16) were evaluated in this study. The choice of varieties was dependent on final consumer acceptability, availability of mature bunches, and ability to change color from green to yellow during ripening. Mpologoma is a popular local cooking variety grown by Ugandan farmers and produced for home consumption. Harvested bunches were declustered, fingers plucked and labelled. Thereafter, 100 fingers from each variety were treated with 1-MCP in sealed boxes for 24 hours, while 100 fingers were kept as a control. The bananas were observed for changes in the physico-chemical and sensory attributes, as well as green life during storage. Data was analyzed using XLSTAT (Student 2020.5.1.1063). The rate of respiration and ethylene production were significantly lower (P<0.05) in 1- MCP treated bananas than in the controls over the green life period. The rate of increase of total soluble sugars (TSS) was significantly higher (P<0.05) in the control than in treated bananas. 1-MCP treatment did not have a significant effect (P<0.05) on the dry matter content, titratable acidity and sensory attributes of the cooking bananas under study. For texture, no statistical differences (P<0.05) were obtained in the different treatments because according to the settings, no numerical values were obtained from the texture analyser on soft bananas yet 1-MCP treatment delayed softening of the banana peel and pulp especially the hybrids during storage by three to four day. Cooking bananas treated with 1-MCP displayed delayed ripening. Indigenous bananas treated with 1-MCP stayed green for 16 to 18 days while their controls stayed green for about 13 days. On the other hand, 1-MCP treated hybrid banana varieties stayed green for 12 to 13 days while their controls stayed green for about six days. However, no significant differences (P<0.05) were observed in the sensory attributes of the steamed bananas (both treated and un-treated green banana samples) during the storage period. Despite that, the sensory characteristics of the indigenous and hybrid cultivars remained significantly different (P<0.05). From the results of the study, it was observed that 1-MCP (at 5 ppm used in this study) can be used to extend postharvest green life of Ugandan indigenous and hybrid cooking bananas by about 5 days while maintaining their physico-chemical and sensory attributes. KEY WORDS: 1-methylcyclopropene, Ethylene, Indigenous and hybrid cooking bananas, Physico-chemical attributes, Postharvest green life
Optimization of fermentation conditions of naturally processed Arabica coffee (Coffea Arabica) in Uganda
(Kyambogo University (Unpublished work), 2024-09) Khassim, Zulfat
Coffee is very popular due to the unique sensory characteristics of its brew. This research aimed to determine the best fermentation method and duration for Arabica coffee with respect to its volatile, physicochemical, and sensory components. Gas chromatography/mass spectrophotometry (GCMS) was used to examine volatile chemicals that had been extracted using solid-phase micro extraction (SPME). Descriptive sensory evaluation with 8 trained panelists was used to assess the cup quality. Response Surface Methodology and Principle Component Analysis were used for data analysis. Significant models were generated to describe the relationship between fermentation time, fermentation type, and the physicochemical, and sensory properties as well as volatile compounds of Arabica coffee. Both fermentation type and time had an impact on sensory qualities such as fragrance/aroma, flavor, sweetness, acidity, body, balance, aftertaste, uniformity, and cleanliness. The optimum fermentation time and fermentation type were 16.8 hours and spontaneous fermentation respectively. Principle component analysis was performed to relate sensory attributes with physicochemical properties and volatile compounds. Furaneol, coffee temperature, 3-ethyl-2-hydroxy-2-cyclopenten-1-one, and acetaldehyde were positively correlated to each other. 1-(1H-pyrrol-2-yl)-ethanone, furan were related, 3-hydroxy-2-butanone, acetic acid, brix, 2,3-pentanedione and ethyl isovalerate, 2,3-butanedione (diacetyl), 2-methylbutanal, 3-methylbutanal were positively correlated, and there was a positive correlation between 2-butanone, pH, pyrazines.
Development and characterization of products from selected varieties of sweet potatoes (Ipomoea batatas L.) in Uganda
(Kyambogo University (Unpublished work), 2024-10) Acio, Catherine
This research aimed to develop and characterize sweet potato products from selected varieties from Uganda as a potential raw resource for the food processing sector. The selected local varieties included Sukali, New Kawogo, Mubalila Bbali, Njule, Nakakande, and Kasanda and the hybrid varieties included Narospot 1, Naspot 12, Naspot 8, and Naspot 13. The sweet potato varieties (both local and hybrid) were sourced from a multiplication farmer at Bombo, Luweero district and brought to the laboratory for analysis. The varieties were characterized for their vitamin A content, total polyphenols, starch, protein, fiber, ash, carbohydrate and dry matter content. The starch extracted from the sweet potatoes was also characterized. Sweet potato products, including bread, cakes, cookies, instant porridge and meal powder were developed using Naspot 13 and Kasanda. The instant porridge and meal were made by incorporating sweet potato flour with silverfish, egg, and milk powders, followed by extrusion cooking and milling. These products were evaluated for texture, rheological properties, and other nutritional attributes. The selected local and hybrid sweet potato varieties exhibited significant variation in both skin and pulp color. The dry matter content ranged between 29.5% in Nakakande and 42.8% in New Kawogo. Beta-carotene content varied between 6.48 μg/g in Sukali and 65.56 μg/g in Njule. Polyphenol content ranged between 0.178% and 0.554%, in Naspot 8 and Kasanda respectively. pH values ranged between 6.42 and 7.60 in Kasanda and Nakakande respectively. Crude ash content varied between 0.25% and 1.67%, with Nakakande and Naspot 13 having the lowest and highest values. Crude fat content ranged between 1.67% and 5.50%, with Narospot 1 and Naspot 12 having the lowest and highest values. Crude fiber content ranged between 2.22% and 4.50%, with Mubalila Bbali and Naspot 8 having the lowest and highest values. Protein content ranged between 1.79% and 4.77%, with Mubalila Bbali and Naspot 8 having the lowest and highest values. Moisture content ranged between 57.2% and 70.5%, with New Kawogo and Nakakande having the lowest and highest values. Total carbohydrate content ranged between 21.8% and 32.2%, with Njule and New Kawogo having the lowest and highest values. Regarding the physicochemical characteristics of the extracted starch, its water holding capacity ranged between 0.81 g/g and 1.20 g/g; Peak viscosity ranged between 10834 cP and 14399 cP; trough viscosity between 1081 cP and 5353 cP; breakdown between 6671 cP and 10194 cP; final viscosity between 3101 cP and 5867 cP; setback viscosity between 152 cP and 2803 cP. Peak time varied between 3.4 seconds and 4.1 seconds, and pasting temperature ranged between 73.2°C and 78.9°C. The developed products i.e. bread at 30% sweet potato flour inclusion and cakes & cookies upto 80% sweet potato flour inclusion exhibited good sensory and consumer acceptability. While increase in amount of sweet potato flour led to firmer textures and reduced sensory acceptance, moderate inclusion (up to 10-12.5%) offered a good balance between optimizing substitution and maintaining consumer preferences. The proximate composition and texture of bread, cookies, and cakes made from sweet potato flour (Naspot 13 & Kasanda) varied according to the formulation. These products exhibited good sensory and consumer acceptability comparable to those made with 100% wheat flour. The vitamin A and beta-carotene content were notably higher in products derived from Naspot 13 (orange-fleshed variety). The formulated meal and porridge, which included silverfish, egg, and milk powders, had varying protein content averaging 15%. Sensory acceptability varied based on milk powder and silverfish content. In conclusion, the selected Ugandan sweet potato varieties (both local and hybrid) demonstrated favorable functional properties and can be effectively used to produce high-quality baked products at high levels of wheat substitution, especially in cakes and cookies.
Quality and stability of cricket (Acheta domesticus) enriched cassava (Manihot esculenta Crantz) flour
(Kyambogo University (Unpublished work), 2024-08) Jjoloba, Wilberforce
Cassava, being a starchy staple, contains minimal protein and other nutrients, which limits its utilisation as a complete food. Incorporating edible insects, such as house crickets, has shown promise in improving the nutritional profile of staple foods like maize and millet. However, the impact of house cricket powder incorporation on cassava flour properties remains relatively unexplored. This study aimed to enhance the nutritional composition of cassava flour using cricket powder without compromising its nutritional, functional, safety, shelf life and sensory properties. By so doing, the study contributes to the resilience and well-being of populations reliant on cassava as a staple food. Four improved cassava varieties i.e. Mkumba, NAROCASS 1, NASSE 3 and NASSE 14 and one local variety i.e. Magana were selected based on their agronomical properties and processed into cassava flour. House crickets underwent two treatments prior to processing into cricket powder. Composites were formulated using Design expert software after which they were screened to obtain the sensorialy acceptable formulation for chemical, functional, microbial and shelf life studies. Standard methods were used for all analyses. Findings were analysed using ANOVA. Sensory analysis revealed a significant negative impact of cricket powder on colour, aroma, aftertaste, and overall acceptability. Protein content significantly increased by 5.54% (p <0.05) and fat content 2.21% (p <0.05) in cassava-cricket composite flours. Solubility decreased while swelling capacity and oil absorption capacity increased with cricket powder incorporation. Chemical analysis showed absence of aflatoxin and pesticide residues, while microbiological assays showed absence of Salmonella sp. and Staphylococcus aureus. Over a 24-week storage period, cassava-cricket composite flours’ moisture content, peroxide value, and acid value, remained with the range recommended by Codex Alimentarius and East African standards. Total plate count and total coliform counts declined consistently during the shelf life study period, indicating microbial suppression. Sensory attributes and levels of yeast and moulds remained consistent throughout storage, suggesting the stability of cassava-cricket composite flours over 24 weeks. Findings suggest that cricket powder enhances the nutritional value of cassava flour without compromising safety, functionality, shelf life or sensory acceptability. Further studies could explore the use of cricket powder in different food matrices.
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.
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.
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.
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.
Proximate, mineral, fatty acid composition and quality of the oil obtained from landrace and improved sesame (sesamum indicum) seeds grown in northern Uganda
(Kyambogo University [unpublished work], 2023-10) Nayiga, Lydia
Uganda is the seventh sesame-producing country in Africa and ninth in the world. Sesame is a non-traditional cash crop with tremendous export potential. Data on composition of sesame in Uganda is scarce, making the planning of the sesame value chain a challenge. Landraces (Ajimo, Otara, Arut) and improved sesame seeds (Sesim I, Sesim II and Sesim III) were obtained from MAAIF Vegetable Oil Development Project (VODP-Phase 2) and NaSARRI, respectively. Proximate composition was determined using methods of the Association of Official Analytical Chemists (AOAC). Fatty acids (FA) were determined as FAME using GC-FID. Minerals were determined using Atomic Absorption Spectrophotometry (AAS). Quality parameters; refractive index (RI), acid value (AV), peroxide value (PV), and iodine value (IV) of oil extracted from sesame seeds were determined by AOAC and the American Oil Chemists Society (AOCS) methods. Findings from the study showed a significant difference in moisture, fat, protein, crude fibre, crude ash and carbohydrates between the landrace and improved seeds. FA composition was variable between landraces and improved sesame seeds. The major FA of sesame oil were oleic acid (18:1ꞷ9), linoleic acid (18:2ꞷ6), palmitic acid (16:0) and stearic acid (18:0). Unsaturated FA predominated over the SFA. Landraces had a higher content of 18:2ꞷ6 than the improved sesame seeds while improved sesame seeds had higher amounts of 18:1ꞷ9. Mineral concentrations varied from 521.45 to 665.15 mg/100 g for P, 315.70 to 458.22 mg/100 g for K, 199.60 to 363.16 mg/100 g for Mg, 69.29 to 83.15 mg/100 g for Na, 50.42 to 56.40 mg/100 g for Ca, 2.32 to 2.86 mg/100 g for Fe, 1.12 to 2.77 mg/100 g for Zn and 1.13 to 1.59 mg/100 g for Cu. Oil quality parameters were within the international standards for oils meant for human consumption. These findings provide insights on nutrient composition of sesame seeds in Uganda, highlighting their potential health benefits and quality for culinary use and oil extraction.
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.
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.
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.
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.
Relationship between physicochemical and sensory properties of selected local and hybrid cooking bananas in Uganda
(Kyambogo University(Un published work), 2021-01) Kisenyi, Willy Nelson
The East African Highland Cooking bananas are a staple food in Uganda. In this work, the relationship between sensory characteristics and the physicochemical properties of 23 local and hybrid cooking bananas was studied. The selected cultivars included officially released hybrids (n=2), hybrids still under evaluation (n= 12), female parents used in breeding (n=3), and popular local East African Highland (EA-AAA) cooking bananas (n=6). Peel thickness, finger length, TSS, TA, dry matter, starch content including amylase & amylopectin composition, crude fat, ash, protein, texture, phenolic compounds, tannins and total flavonoids were determined using standard methods. Results of proximate composition and starch composition indicated that local cultivars Mpologoma, Mbwazirume, and Muvubo had significantly (p < 0.05) higher values of moisture, crude fat, ash, protein and amylase than hybrids. Hybrids NARITA 6 and NARITA 2 had significantly (p < 0.000 1) the highest dry matter content of 27.94 % and 28.09 %, respectively. Hybrids NA RITA 2, NA RITA 11 , l 79 I 4S- 24 and ARITA 24 had relatively higher phenolic compounds than most of the local cultivars. To examine the eating quality characteristics, the traditional steam and mash method was used. Thirteen trained panellists were used to assess sensory characteristics of the cooked bananas. The main sensory characteristics of cooked bananas according to panellists were; a homogeneous yellow colour, moist smooth and soft texture, an aroma of bananas in leaves, a mild sweet taste and low astringency. Sourness, high astringency, pale yellow, blackish & mottled colours, extreme firmness and too soft texture were described as undesirable characteristics. Some hybrid cultivars (N2 1, N15, NI 1, N8, 17914S-24, N2 and N6) had significantly (p < 0.05) lower scores for sensory characteristics than the local bananas. However, the sensory scores of other hybrids such as M32, ARITA 17, M9, M33 and NARITA 24 were not significantly different from those of local cultivars. According to the PCA, flavonoids and ash content are correlated with astringency (r = 0.014, r = -0.006), stickiness (r =0.3 10, r = 0.402), mouldability (r = 0. 12 1, r = 0.226) & smoothness (r = 0.130, r = 0.295) of hybrids N8, N2 l, & 179 I 4S-24. Total tannins and amylopectin content determine the moistness (r = 0.454, r = 0. 193) of cooked bananas as observed in Nakitembe, M32, and Enzirabahima. Sourness is correlated with total phenols (r = 0.453) content in hybrids 11, NI5. The large finger circumference is explained by the high dry matter and high amylase content (r = -0.064, r = 0.090) in NI I & Nl5. Firmness and hardness are explained by high search (r =0.244, r = 0.282) content mainly in hybrids N2, N6, M9 & M33 and a local cultivar Yfuuka. High starch content was associated (r = 0.453) with a firm and hard texture while Matooke taste is correlated with high titratable acidity (r = 0.404) while sweetness & a yellow colour and homogeneous colour are associated with TSS (r = 0.405, r = 0.581, r = 0.578) in Kibuzi, Nakitembe, Nakawere, Muvubo, Enzirabahima, Kabucuragye, M32, N 14, N24 and N 17. Therefore, these quality properties could be used by breeders as parameters for screening clones for food quality to meet consumer expectations.
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 .
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 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.
Non-cancer health risks associated with pesticide residues and heavy metal exposures in locally manufactured cereal-based baby foods in Kampala city
(Kyambogo University (Unpublished work), 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.

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