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ItemDevelopment and Preservation of a Starter Culture for Commercial Production of Bongo, a Traditional Fermented Milk Beverage from Uganda.(Makerere University, 2025-11-14)Bongo is a popular traditional fermented milk produced spontaneously, or by backslopping. This predisposes the product to microbial contamination, slow fermentation and variations in product sensory properties. Controlled fermentation using defined starter cultures is vital to address these challenges. Three lactic acid bacteria (LAB) previously isolated based on milk acidification and coagulation, Lacticaseibacillus rhamnosus BM55, Lactococcus lactis BM01 and Leuconostoc pseudomesenteroides BM70 were used in this study to evaluate their potential as starter cultures in fermented cows’ milk. The isolates were evaluated both individually and in combination. Microbial counts, pH, titratable acidity, viscosity, flavour development, syneresis and consumer acceptability were determined using standard methods. The sensory profile of Bongo prepared using the cultures, as well as the spontaneously fermented Bongo, was described using Quantitative Descriptive Analysis (QDA). The relationship between the sensory profile and hedonic scores was determined using preference mapping. The most promising combination of isolates (BM01, BM55 and BM70) was lyophilised in 10% (w/v) skimmed milk and 10% (w/v) soluble starch prior to being stored under refrigeration (4 °C) for 6 months. Survival rate and fermentation characteristics (pH, viscosity, titratable acidity and LAB counts) of Bongo made using the starter culture were determined. The combination of all the three isolates showed the highest potential application as a starter culture with the lowest pH, optimal viscosity, minimal syneresis and enhanced flavour development comparable to that of spontaneously produced Bongo. This was further confirmed by the QDA results. Significant correlations were observed between lumpiness, smoothness and astringency underscoring the importance of the choice of microorganism on the product attributes of Bongo. Texture was the major factor responsible for the differences between the Bongo samples produced by the different starter culture isolates. There was a decline in viability and fermentation ability post lyophilisation and storage because the cryoprotectants do not fully prevent cell damage due to freezing effects and dehydration. LAB lyophilised in skimmed milk showed the highest viability (92%) when compared to LAB lyophilised in soluble starch (78%). Bongo made using LAB lyophilised in skimmed milk had a higher viscosity, lower pH, higher titratable acidity compared to that made with LAB lyophilised in soluble starch implying that skimmed milk had a better protective power. The freeze dried culture maintained acidification ability in the first four months of storage at 4 °C. The mixed starter culture containing Lactococcus lactis BM01; Lacticaseibacillus rhamnosus BM55 and Leuconostoc pseudomesenteroides BM70 lyophilised in 10% (w/v) skimmed milk could be adopted for commercial scale processing of Bongo.
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ItemAcrylamide content of selected processed Ugandan Coffee varieties(Makerere University, 2025)Coffee beans are roasted at high temperatures above 120 oC, which results in a Maillard reaction leading to acrylamide formation. Acrylamide is carcinogenic and causes damage to the nervous and renal systems of the body. The formation of acrylamide in coffee is dependent on factors such as roasting time, temperature, and bean variety. Much as there is a plethora of information regarding acrylamide and its presence in coffee, there still exists a dearth of literature on the effect of processing coffee on acrylamide levels, specifically for coffee varieties grown in Uganda. Therefore, this study assessed the effect of processing on acrylamide levels of selected Ugandan coffee varieties. Coffee cherries of eleven varieties were collected from Luwero district and sun-dried to a moisture content below 12%. The dried coffee cherries were hulled and analyzed for moisture content, screen retention, out-turn, defect count, glucose, fructose, and crude protein contents using standard methods. The coffee beans were then roasted and brewed under different conditions then analyzed for acrylamide using Liquid Chromatography–Mass Spectrometry. The moisture content, defect count, and out turn 2 ranged from 8.7 to 11.0 %, 3.2 to 18.5 %, 81.5 to 96.8 %, and 42.1 to 57.1%, respectively. The overall retention of beans on screen 15 for Kituza Robusta (KR) 6, Kisansa (KS) and Nganda (NG) varieties was above 60%. Glucose levels ranged from 1.7 to 2.9 g/100g, while fructose ranged from 0.9 to 6.9 g/100g, and the crude protein was 11.0 to 16.8%. The acrylamide levels varied significantly (p<0.05) across coffee varieties, with the highest occurring in the Elite D (ED) variety, with 444.8 µg/kg at dark roast. Acrylamide levels also varied significantly (p<0.05) with roasting time. Higher levels of acrylamide occurred in the dark roasted coffee and were lowest in very dark roasted coffee. Acrylamide levels for coffee brewed using the espresso method were 1.7 to 21.9 µg/L. They were highest in Kisansa coffee brewed for 60 s and lowest in the same variety brewed for 10 s. Whereas for the coffee brewed using the French press method, the acrylamide levels were 9.2 to 66.3 µg/L, with the highest (p<0.05) occurring in KR7 brewed for 10 min and the lowest in Kisansa brewed for 3 min. Therefore, the study indicated that there are varietal differences in the physicochemical properties of coffee beans, which in turn influence their acrylamide levels upon roasting and brewing.
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ItemDevelopment and preservation of a starter culture for commercial production of bongo, a traditional fermented milk beverage from Uganda(Makerere University, 2025)Bongo is a popular traditional fermented milk produced spontaneously, or by backslopping. This predisposes the product to microbial contamination, slow fermentation and variations in product sensory properties. Controlled fermentation using defined starter cultures is vital to address these challenges. Three lactic acid bacteria (LAB) previously isolated based on milk acidification and coagulation, Lacticaseibacillus rhamnosus BM55, Lactococcus lactis BM01 and Leuconostoc pseudomesenteroides BM70 were used in this study to evaluate their potential as starter cultures in fermented cows’ milk. The isolates were evaluated both individually and in combination. Microbial counts, pH, titratable acidity, viscosity, flavour development, syneresis and consumer acceptability were determined using standard methods. The sensory profile of Bongo prepared using the cultures, as well as the spontaneously fermented Bongo, was described using Quantitative Descriptive Analysis (QDA). The relationship between the sensory profile and hedonic scores was determined using preference mapping. The most promising combination of isolates (BM01, BM55 and BM70) was lyophilised in 10% (w/v) skimmed milk and 10% (w/v) soluble starch prior to being stored under refrigeration (4 °C) for 6 months. Survival rate and fermentation characteristics (pH, viscosity, titratable acidity and LAB counts) of Bongo made using the starter culture were determined. The combination of all the three isolates showed the highest potential application as a starter culture with the lowest pH, optimal viscosity, minimal syneresis and enhanced flavour development comparable to that of spontaneously produced Bongo. This was further confirmed by the QDA results. Significant correlations were observed between lumpiness, smoothness and astringency underscoring the importance of the choice of microorganism on the product attributes of Bongo. Texture was the major factor responsible for the differences between the Bongo samples produced by the different starter culture isolates. There was a decline in viability and fermentation ability post lyophilisation and storage because the cryoprotectants do not fully prevent cell damage due to freezing effects and dehydration. LAB lyophilised in skimmed milk showed the highest viability (92%) when compared to LAB lyophilised in soluble starch (78%). Bongo made using LAB lyophilised in skimmed milk had a higher viscosity, lower pH, higher titratable acidity compared to that made with LAB lyophilised in soluble starch implying that skimmed milk had a better protective power. The freeze dried culture maintained acidification ability in the first four months of storage at 4 °C. The mixed starter culture containing Lactococcus lactis BM01; Lacticaseibacillus rhamnosus BM55 and Leuconostoc pseudomesenteroides BM70 lyophilised in 10% (w/v) skimmed milk could be adopted for commercial scale processing of Bongo.
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ItemPhysico-chemical quality, microbial contamination, health risks, and community knowledge and perceptions of underground well water in commercial establishments of Kampala(Makerere University, 2025)Underground wells are a major water source in Kampala but pose contamination and health risks due to limited community knowledge and poor sanitation. This study assessed the physico-chemical quality, microbial contamination, health risks, and community knowledge, perceptions, and practices regarding underground well water quality in commercial establishments in Kampala. A cross-sectional study was conducted among 302 respondents and 42 water samples from Kawempe, Central, and Makindye Divisions. Data collection followed standard analytical procedures, and results were compared with EAS and WHO water quality guidelines. Quantitative Microbial Risk Assessment (QMRA) based on E. coli data applied the Beta-Poisson model for risk estimation. Respondents (52% female, 48% male) were mainly aged 28-37 years; 48% had knowledge about underground water quality but 42.58% distrusted its safety. Education, gender, and age significantly influenced water-related knowledge and practices. Most physico-chemical parameters pH, hardness, EC, TDS, and iron fell within acceptable limits, except at Kisugu TC, Nsambya 1, and Nabukeera Plaza, where non-compliance occurred. Microbial results revealed high contamination with total coliforms and E. coli, especially in the Central Division, indicating fecal pollution and risk of waterborne diseases. Salmonellae and H. pylori were also detected in several sites. Regulatory compliance for E. coli and TC was low (≤24%), while Salmonellae showed the highest compliance (81%). QMRA findings showed the highest infection risks in the Central Division, with children more vulnerable than adults. The daily infection probabilities exceeded WHO benchmarks, indicating significant public health threats. While water from underground wells in Kampala is largely chemically safe, microbial contamination remains severe, posing serious health risks, particularly to children. The study underscores the urgent need for enhanced water quality monitoring, community education, sanitation improvements, and sustainable groundwater management policies.
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ItemSafety of ready-to-eat foods in highway tourist stopover food service establishments in Uganda(Makerere University, 2025)In Uganda, highway tourist stop-over food service establishments (HTSFEs) are frequented by tourists to and from upcountry destinations. Their setup and operations are, therefore, critical in ensuring food safety. The HTSFEs had previously not been profiled, and their operations were poorly documented. This study focused on profiling these establishments, evaluating food safety knowledge, attitudes, and practices of food handlers, and analyzing the microbiological quality and aflatoxin levels of RTE foods and the potential carcinogenic risk leading to hepatocellular carcinoma as a result of the consumption of such foods. The study adopted a cross-sectional design involving the collection of quantitative data from managers (n = 30) of HTSFEs. An interviewer-administered questionnaire and an observational checklist were used to collect data. The research also explored food handlers' (n = 108) food safety knowledge, attitudes, and practices, using a structural equation model. Data was collected using a self-administered structured questionnaire. The study further evaluated the microbiological quality of 100 samples of Ready-To-Eat (RTE) foods in highway tourist stop-over food service establishments in Uganda, following International Standards Organisation (ISO) protocols. The RTE foods included fresh fruit juice, vegetable salads, fried eggs, and vegetables wrapped in a chapati (‘Rolex’), beef samosas, roasted chicken, and roasted beef. The samples were examined for the presence of Enterobacteriaceae, fungi, presumptive Escherichia coli, Staphylococcus spp., Salmonella spp., and Total Plate Count (TPC). A total of 84 food samples of maize bread (posho) and groundnut sauce were collected from 15 purposively selected HTSFEs. Samples from both foodstuffs were assessed for total aflatoxins (TAFs) and aflatoxin B1 (AFB1) using the Enzyme-Linked Immunosorbent Assay (ELISA technique). The risk of developing primary liver cancer (hepatocellular carcinoma) was computed using models recommended by the joint FAO/WHO expert committee on food additives based on Estimated Dietary Intake (EDI) and average potency. The EDI was determined based on daily food intake, mean level of AFB1, and average body weight. Based on the food safety compliance scores, none of the HTSFE belonged to grade A, and the rest were as follows: B (36.6%), C (30%), and Non-graded (33.3%). Most of the HTSFE were located in Western (47.6%) and Eastern Uganda (36.7%). None of the HTSFE had a food safety management system. A substantial percentage (58.6%) was inspected by the Uganda Tourism Board (UTB) in addition to either the local council or the city council. Half of the food handlers had adequate knowledge of food safety and good practices. Food safety knowledge significantly influenced practices (β = 0.37, p < 0.05), while attitude had an insignificant and negative effect on practices (β = -0.04, p > 0.05). Overall, the microbiological standard set for RTE foods by the Uganda National Bureau of Standards (UNBS) and the East African Community (EAC) was violated in 40% of the food samples tested. All fresh fruit juices exceeded specifications for TPC and fungi. Some of the vegetable salads (44.4%), ‘Rolex’ (25%), beef samosas (75%), roasted chicken (80%), and roasted beef (38.5% conformed to the specifications for Staphylococcus spp. All the Rolex and beef samosas conformed to the specifications for E. coli. Some of the fresh fruit juices (13%), vegetable salad (38.9%), roasted chicken (50%), and roasted beef (38.5%) conformed to the standard specifications for E. coli. All the beef samosas conformed to the specifications for Enterobacteriaceae. Salmonella spp. were not detected in any of the food samples. There was a significant difference (p < 0.05) in the microbiological quality of RTE from the different grades of HTSFE. RTE food samples from grade B HTSFE presented with better microbiological quality. All groundnut sauce samples had quantifiable levels of total aflatoxins (TAFs) ranging from 20.64 - 193.7µg/kg and AFB1 ranging from 12.82 – 53.95µg/kg, well above the regulatory limits of 10µg/kg and 5µg/kg, respectively. Similarly, all posho samples had TAFs (13.79 – 95.98 µg/kg) above the regulatory limits of 10µg/kg. Only 15.6% of the posho samples were within the regulatory limit for AFB1 of 5µg/kg There was no significant difference (p < 0.05) in total aflatoxin concentration and AFB1 in food samples from the different grades of HTSFE. The estimated dietary intake (EDI) for AFB1 ranged between 26.15 and 45.43 ng/kg bw/day, resulting from the consumption of groundnut sauce and posho, respectively. The margin of exposure was 15.29 (groundnut sauce) and 8.8 (posho). The derived risk of developing primary liver cancer was 1.0208 and 0.5876 cases per 100,000 people per year from posho and groundnut sauce consumption, respectively. This is potentially dangerous to the consumers This study emphasizes the importance of letter-grading of HTSFE, implementation of food safety management systems, law enforcement, consideration of the microbiological quality of RTE foods in the grading criteria, sensitization of key stakeholders in the food value chain on proper food handling, and better training of food handlers to ensure the safety of RTE foods in Uganda’s HTSFE, contributing to consumer protection and sustainable tourism