Department of Food Processing Technology

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Risk assessment for the occurrence of escherichia coli 0157:H7 in indigenous fermented milk (lee naga a agbora) produced in Uganda
(AJOL: Animal Production Research Advances., 2009) Wawa, SA; Sserunjogi, ML; Ogwok, P; Mugampoza, D
Different types of indigenous fermented milks are widely consumed in pastoralist communities of Africa, including Uganda. Local processing of milk generally takes place under uncontrolled hygienic conditions. Lee naga a agbora, a locally fermented milk product in northern Uganda, was evaluated for microbial contamination. The changes in pH, Total Plate Counts (TPC), Total Coliforms (TC), yeasts and moulds, and Escherichia coli 0157:H7, particularly its survival during different stages of fermentation were studied. The pH was found to decrease with fermentation time (6.54 to 4.54). E. coli was detected in most samples of Lee naga a agbora and its occurrence was observed throughout the fermentation period. The mean value of TPC (6.60± 0.10 log cfu ml-1) at the start of fermentation was significantly different (p<0.05) from that at 144 hours (7.91± 0.10 log cfu ml-1). The TPC was not significantly different (p>0.05) between 48 and 72 hours. The rate of decrease in TC counts in the initial fermentation period (0 to 48 hours) was lower than the later stages of fermentation (48 to 144 hours). Yeast and mould counts increased with fermentation time (6.20 to 7.42 log cfu ml-1). On the whole, there is risk associated with consumption of Lee naga a agbora given the occurrence of E. Coli.
Occurrence of listeria monocytogenes in bulked raw milk and traditionally fermented dairy products in Uganda
(African Journal of Food, Agriculture, Nutrition and Development., 2011) Mugampoza, D; Muyanja, CMBK; Ogwok, P; Serunjogi, ML; Nasinyama, GW
Bulked raw milk, locally processed yoghurt (LPY) and Bongo, a traditionally fermented dairy product sold at most informal milk cooling points in Uganda, were assessed for occurrence of Listeria spp. and Listeria monocytogenes. Total plate counts (TPC), holding temperature, pH and titratable acidity were also determined in all the milk products at the point of collection using standard methods. A total of 40 samples of bulked raw milk and 30 for each of LPY and Bongo were examined. Listeria spp. was higher in bulked raw milk than in fermented milk. Listeria spp. were detected in 60% of bulked raw milk, 30% of LPY and 15% of Bongo samples. Bulked raw milk had significantly higher (p<0.05) mean Listeria counts (3.10±0.06 log10 cfu mL-1) than LPY and Bongo, 0.82±0.18 and 0.32±0.18 log10 cfu mL-1, respectively. L. monocytogenes was isolated from 13 % of bulked raw milk, 3.0% of LPY but was not detectable in Bongo. Total plate count was significantly different (p<0.05) among the different milk types studied. Bongo had higher TPC (9.00±0.13 log10 cfu mL-1) than bulked raw milk (8.40±0.11 log10 cfu mL-1) and LPY (7.40±0.13 log10 cfu mL-1). The mean total plate counts (4.90 to 9.00±0.13 log10 cfu mL-1) of the fermented dairy products were within the acceptable limits for human consumption. The TPC for bulked raw milk (8.40±0.11 log10 cfu mL-1) was higher than the recommended values of national and international standards. Temperature, pH and titratable acidity were significantly different (p<0.05) among the different milk types. Holding temperature ranged from 5.40 to 8.60oC, pH was 4.20±0.04 to 6.10±0.04 whereas titratable acidity ranged from 0.22±0.01 to 089±0.01%. Listeria counts were not statistically predictable (p>0.05) from variation in the combined effect of pH, percent titratable acidity and temperature. Results of this study demonstrate a high risk associated with consumption of bulked raw milk and fermented dairy products in due to occurrence of Listeria spp.
Nucleotide degradation products, total volatile basic nitrogen, sensory and microbiological quality of Nile perch(Lates niloticus) fillets under chilled storage
(Journal of Microbiology, Biotechnology and Food sciences, 2012-11) Amegovu, Andrew Kiri; Sserunjogi, Mohammed Luyima; Ogwok, Patrick; Makokha, Vincent
Degradation products of adenosine nucleotide and total volatile basic nitrogen (TVBN) concentration provide means of ascertaining freshness of commercial fish products. A complementary sensory analysis has also been adopted by export markets for assessing the quality of fresh fish. Nucleotide breakdown products and TVBN was determined in fresh fillets from beach seined and gill netted Nile perch, a highly commercialized freshwater fish from Lake Victoria (Uganda), under chilled storage. Microbiological and sensory qualities were also evaluated. Total plate and Pseudomonas spp. counts positively correlated with TVBN. Basing on sensory, microbiological and biochemical attributes of the fillets, shelf-life of gill netted Nile perch was lower (13 days) than that of the beach seined (17 days). Fillets of beach seined Nile perch have a better keeping quality than that of the gill netted.
Organochlorine pesticide residues in skin, flesh and whole carrots (Daucus carota) from markets around Lake Victoria basin, Uganda
(Taylor & Francis online: International Journal of Environmental Studies., 2013) Nannyonga, Stella; Kiremire, Bernard T.; Ogwok, Patrick; Nyanzi, Steven A.; Sserunjogi, Mohammed L.; Wasswa, John
Residual concentrations of organochlorine pesticides in vegetables cause concern because of their adverse health effects. Pesticides have been applied in agricultural production and vector control in Uganda. Vegetables may absorb high residual levels of cyclodienes necessitating regular monitoring. Carrots are commonly consumed in Uganda as raw salads or components of different dishes. A gas chromatograph with electron capture detector was used to quantify organochlorine pesticides. Pesticide residues were confirmed by gas chromatography with a mass spectrometer. Trace amounts of 4,4′-dichlorodiphenyltrichloroethane (DDT), 2,4′-DDT, 2,4′-dichlorodiphenylchloroethane (DDE), α- endosulphan, β-endosulphan, α-lindane, γ-lindane and dieldrin were detected in carrots. Levels of organochlorine residues in carrots were below the maximum residue limits considered safe for human consumption by Codex Alimentarius and the European Union Commission.
Determining food insecurity: An application of the Rasch Model with household survey data in Uganda.
(International Journal of Food Science, 2014-11) Owino, Abraham; Wesonga, Ronald; Nabugoomu, Fabian
The inexplicable nature of food insecurity in parts of Uganda and worldwide necessitated an investigation into the nature, extent, and differentials of household food security. The main objective of this study was to examine the food security dynamics and model household food insecurity. The Rasch modelling approach was employed on a dataset from a sample of 1175 (Tororo = 577; Busia = 598) randomly selected households in the year 2010. All households provided responses to the food security questions and none was omitted from the analysis. At 5 percent level of significance the analysis indicated that Tororo district average food security assessment (0.137 ± 0.181) was lower than that for Busia district (0.768 ± 0.177). All the mean square fit statistics were in the range of 0.5 to 1.5, and none of them showed any signs of distortion, degradation, or less productivity for measurement. This confirmed that items used in this study were very productive for measurement of food security in the study area. The study recommends further analysis where item responses are ordered polytomous rather than the dichotomous item response functions used. Furthermore, consideration should be given to fit models that allow for different latent distributions for households with children and those without children and possibly other subgroups of respondents.
Mathematical modelling of color, texture kinetics and sensory attributes characterisation of ripening bananas for waste critical point determination
(Elsevier: Journal of Food Engineering., 2016-12) Nannyonga, Stella; Bakalis, Serafim; Andrews, James; Mugampoza, Ediriisa; Gkatzionis, Kostas
It is vital to correlate the instrumental and non-instrumental analyses of food products so as to determine the product waste critical point. Texture and color (instrumental) were determined by a universal testing machine (UTM) and colorimetry respectively to ascertain the kinetics of bananas during ripening. While deterministic, descriptive and ranking sensory tests were employed for sensory attributes characterisation. Seven banana color ripening stages were used for color variation and three temperatures (16, 23 and 30 °C) were used to study the kinetics, L, a, b and ΔE were calculated and axial puncture force, PF determined. Logistic model and first order reaction models were used. The sensory attributes results indicated banana waste critical point from stage 6 while instrumental analyses still indicated a model trend up to stage 7.
Human health risk assessment of heavy metals in Kampala (Uganda) drinking water
(Journal of Food Research, 2017) Bamuwamye, M.; Ogwok, P.; Tumuhairwe, V.; Eragu, R.; Nakisozi, H; Ogwang, P.E.
Levels of aluminium, arsenic, cadmium, chromium, copper, iron, mercury, manganese, nickel, lead and zinc in tap water, groundwater-fed protected spring and bottled water were determined. The cancer and non-cancer risks associated with ingestion of heavy metals (HM) were also assessed for both children and adults. Forty seven water samples obtained from five divisions of Kampala city were analyzed using atomic absorption spectrophotometry. Cancer and non-cancer risks were determined using incremental lifetime cancer risk (ILCR) and non-carcinogenic hazard quotient(HQ), respectively. Lead content was higher than permissible limits(PL) according to East African Standard, World Health Organization, European Union and United States Environmental Protection Agency (USEPA). Arsenic showed minor exceedances above guideline values in tap water and groundwater-fed protected spring, whereas mercury, manganese and nickel were higher than PL. Levels of aluminium, cadmium, chromium, copper, iron, and zincwere below the PL. The lifetime risk of developing cancer through the oral route was greater than the USEPA acceptable level for both children and adults, revealing that exposure to HM in drinking water posed an unacceptable potential cancer risk. Arsenic contributed ca. 90% of the ILCR in tap water and groundwater-fed protected spring. The combined non-cancer risk of the HM expressed as hazard index (HI) was greater than one, with values for children being higher than those for adults. Lead contribution towards HI was in all cases above 90%. These results demonstrate the presence of alarming non-cancer risks for children.
Fatty acid profile of wild edible and cultivated mushrooms (Pleurotus ostreatus, Amanita spp and Termitomyces microcarpus)
(Emerald Insight- Nutrition & Food Science, 2017) Patrick, Ogwok; Robert, Muyinda; Henriettah, Nakisozi; Michael, Bamuwamye
Purpose The aim of this paper is to investigate fat content and fatty acid profile of cultivated (Pleurotus ostreatus) and wild edible mushrooms (Amanita spp and Termitomyces microcarpus). Design/methodology/approach Pleurotus ostreatus was grown in soil and on cotton seed husks in mushroom growing rooms at Busitema University, Uganda. T. microcarpus and Amanita spp were collected from the wild. Freshly harvested mushrooms were dried at 60°C for 48 h in a hot air oven. Oil was extracted using a Clevenger apparatus. Fatty acid analysis was done using gas chromatography with flame ionization detection. Findings Fat content ranged between 0.24 and 5.23 per cent. Variation was noted between P. ostreatus grown in soil and on cotton seed husks (p = 0.0090). Similarly, Amanita spp and T. microcarpus had differing fat contents (p = 0.0098). Polyunsaturated fatty acids (PUFA) predominated over saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). Linoleic acid (LA) was the most abundant fatty acid (FA) (30.91 to 54.35 per cent). It varied between Amanita spp and T. microcarpus (p = 0.0001) but not between substrates (p = 0.1891). Ratios of PUFA/SFA, MUFA/SFA and PUFA/MUFA were within the desirable ranges. Omega-6 FA/ω-3 FA ratio was higher than that recommended for a healthy diet. However, the low amount of fat in mushrooms suppresses the negative effects of a high ω-6 FA/ω-3 FA ratio. Originality/value Information on FA profile of cultivated and wild edible mushrooms will provide a basis for commercial exploitation of the cultivated mushrooms. This work showed that P. ostreatus, Amanita spp and T. microcarpus are healthy foods with regard to the low fat content and high amounts of LA.
Influence of physicochemical parameters on storage stability: microbiological quality of fresh unpasteurized fruit juices
(Wiley Online Library: Food Science & Nutrition, 2017-08-19) Kaddumukasa, Phoebe P.; Imathiu, Samuel M.; Mathara, Julius M.; Nakavuma, Jesca L.
Fresh juices rich in health and nutritional benefits are valued for their fresh flavor, taste, and aroma. These juices' quality however is affected by factors like temperature, light, and microbiological contamination significantly changing physicochemical parameters and storage stability. Physicochemical and microbiological analyses of passion fruit, pineapple, and mango juices in dark and light bottles at 24°C and 4°C were conducted in Kampala, Uganda for 12 days. Physicochemical parameters significantly reduced (p < .05) storage stability of fresh juices, while no significant changes (p > .05) were observed for the microbiological analyses. pH values ranged from 3.0 to 4.2 (dark) bottles and 2.9 to 4.0 (light) bottles for juices at 24°C and 4°C. °Brix values were from 1.0 to 5.5 for dark and clear bottles at 24°C and 4°C. TTA (%) values ranged from 1.1 to 7.2 (dark) bottles and 1.1 to 7.4 for (light) bottles at 24°C and 4°C. Ascorbic acid content ranged from 3.5 to 61.0 mg/ 100 ml and 5.5 to 56.7 mg/100 ml for juices in dark and clear bottles, respectively. total plate counts ranged from 1.3 × 10___ to 3.3 × 107 CFU/ml (dark bottles at 24°C) to 3.5 × 10³ to 3.3 × 108 CFU/ml (dark bottles at 4°C). For juices in light bottles, total plate counts ranged from 1.8 × 10___ to 8.0 × 107 CFU/ml (24°C) and 2.7 × 10___ to 1.5 × 108 CFU/ml (4°C). High microbial loads suggest the use of poor processing techniques and lack of good hygiene which lower quality and reduce storage stability of juices. Storage temperature greatly reduces physicochemical parameters both at ambient and refrigeration temperatures. This implies that temperature control for unpasteurized juices is critical in order to inhibit microorganism metabolic activities which accelerate biodeterioration leading to spoilage and short shelf life. Fresh unpasteurized juices stored at 24°C and 4°C may safely be consumed within 1 and 2 days, respectively.
Chemical and microbiological characteristics of cocoa beans from Pidie district,Aceh province,Indonesia
(Proceeding of AIC: Health and Life Sciences, 2018) Wahyuni, Martina Fitri; Yunita, Dewi; Yusriana; Aisyah, Yuliani; Lahmer, Rabya A; Mugampoza, Diirisa
This research aimed to examine the chemical and microbiological characteristics of cocoa beans which are used as a raw material in a small-scale chocolate factory in Pidie Jaya District, Aceh Province, Indonesia. The information would be used to improve the overall quality of the cacao beans produced in the country. 8 triplicate samples were collected from a local farmer in Padang Tiji Sub-District, Pidie District, Aceh Province, Indonesia starting from Day 0 to Day 5 fermentation, after drying, and after roasting. The samples were then analysed for water content, pH, lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast, using standard methods. The results showed that the water content slightly decrease during fermentation from 66.60 % to 56.40 % and continued to decline drastically to only 1 % after roasting. Also, the pH declined from 4.91 at Day 0 to 3.93 at Day 3 of fermentation suggesting the growth of LAB and AAB. Then, the pH increased again at Days 4 (4.15) and Days 5 (4.41) this increase occurs because the existing citric acid is used up during fermentation. Before fermentation, the total cell count of yeast was dominant. The highest LAB and AAB growth occurred on the second day of fermentation. These results indicate that the microflora of raw cacao beans and at the end of fermentation is dominated by yeast. It is suspected that the increase in yeast growth at the end of this fermentation is becausecertain types of yeast dominate.
Bioeconomy and the production of novel food products from agro-industrial wastes and residues under the context of food neophobia
(AgBioForum, 2018) Tsimitri, Paraskevi; Michailidis, Anastasios; Loizou, Efstatioa; Mantzouridou, Fani Th; Gkatzionis, Konstantinos; Mugampoza, Ediriisa
Advances in bioeconomy lead to exploitation of wastes for the production of high added-value products. Sometimes, these products face consumer resistance due to a phenomenon known as "neophobia." The aim of this study was the investigation of consumer acceptance/rejection of a novel food product and the segmentation of consumers according to their "food neophobia tendency." A "functional" novel yogurt derived from halloumi whey was chosen as a hypothetical scenario. Data was collected through a survey in typical urban areas in Greece and Cyprus. Statistical analysis revealed three types of "food neophobia tendency" in each study area. Regarding the acceptability of the novel yogurt, consumers are driven by their curiosity about the taste of the novel yogurt, while the main factor of rejection was found in the absence of a health issue.
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.
Textural hardness of selected Ugandan banana cultivars under different processing treatment
(Journal of Food Research, 2018-08) Samuel, Gafuma; G. W., Byarugaba-Bazirake; Ediriisa, Mugampoza
Textural hardness affects cooking time, processing, fuel used and the quality of cooked bananas. In this study, textural hardness of selected Ugandan cooking and juice banana cultivars at green maturity was determined using a Texture Analyzer in raw form and at 30, 50, 70, 90, 100 and 130 min in boiled, steamed, mashed and cooled forms. Raw juice bananas (JB) were significantly harder (36.17N to 42.43N) than raw cooking bananas (CB) (22.37N to 26.72N) (p<0.05). On cooking, JB were harder than CB irrespective of cooking method and time. Boiling and steaming rapidly decreased hardness of the bananas in the first 30 min and decreased slowly thereafter. Boiling produced softer bananas than steaming while mashing resulted in intermediate hardness. Amongst JB, Kayinja was significantly harder than Ndiizi and Kisubi in boiled and steamed forms (p<0.05). Hardness of CB was not significantly different (p>0.05) for all cooking treatments, but Kibuzi was consistently softer while Kazirakwe and Nakabululu were harder than other CB cultivars. Cooling significantly increased (p<0.05) hardness of bananas under all treatments with JB being harder in all cases. Mashed and steamed bananas were harder than boiled bananas when cooled. Bananas cooked longer had lower hardness regardless of cooking method. Overall, textural hardness decreases with cooking time regardless of cooking method. Boiled bananas are softer than mashed or steamed. Cooling increases hardness which follows first order kinetics. Therefore, bananas should either be boiled or steamed and mashed for softer texture and be eaten within 30 min of serving. Juice bananas should not be cooked because of the hard texture established in this s
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.
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
Acid production, growth kinetics and aroma profiles of lactobacillus flora from stilton cheese
(Elsevier: Food Chemistry., 2019-02-23) Mugampoza, Diriisa; Gkatzionis, Konstantinos; Linforth, Robert S.T.; Dodd, Christine E.R.
The effect of Lactobacillus plantarum isolates from Stilton cheese on aroma profiles of milk fermentation was examined. Representative Lb. plantarum isolates were cultured alone and in combination with acid-producing and non-acid producing Lactococcus lactis NCIMB 9918 in UHT milk at 30 & 18 °C for 48 h & 12 weeks, respectively in presence and absence of salt, simulating cheese production and ripening. During long-term ripening, Lb. plantarum grew faster when co-cultured with non-acid producing Lc. lactis in the presence of salt. One isolate of Lb. plantarum produced the highest concentration of alcohols, organic acids and acetoin. Co-culture of Lb. plantarum with acid-producing Lc. lactis enhanced acid and alcohol production, whereas co-inoculation with non-acid producing Lc. lactis increased acetoin synthesis. Lb. plantarum is an incidental organism in cheese and its presence is unpredictable. Occurrence of different genotypes of Lb. plantarum could contribute to batch to batch variation in the cheese aroma characteristics.
Influence of key chemical components on hardness of indigenous cooking and juice banana cultivars from Uganda
(Kyambogo University, 2019-10) Gafuma, Samuel
Bananas undergo significant postharvest losses at the farm, during handling, cooking and serving. Loss of palatability and food mass occurs during serving and consumption due to hardening of cooked banana texture. Texture affects sensory properties of bananas and is very important in determining a good cooked banana. Different banana cultivars differ in hardness and the causes for these differences are not well studied particularly among indigenous cooking and juice banana cultivars grown in Uganda. This study examined influence of key chemical components on hardness of bananas. A total of eleven (11) cooking and three (3) juice banana cultivars grown in and endemic to Uganda, were selected as a case study. Bananas were harvested and used at green mature unripe stage. The samples were analyzed for starch, pectic substances and proximate composition using standard methods, and subsequently assessed the physico-chemical properties of starch and the pectic substances which were the major components. Hardness profile of the 14 banana cultivars was assessed using a texture analyzer. Principle Component Analysis (PCA) revealed that starch and pectic substances were highly and positively correlated with hardness of raw bananas. Then, the role of starch and pectin in influencing hardness of cooked bananas was determined. Sliced bananas were separately treated with pectin, starch and starch-pectin composite before being cooked by steaming combined with mashing and their hardness determined. Pectin was also structurally hydrolyzed from sliced bananas using pectinase (polygalacturonase) and the resulting bananas were cooked in the same way and evaluated for changes in hardness. According to results, water, starch, and pectic substances were the main components of fresh green mature bananas. Juice bananas yielded significantly more dry matter (30 to 33%) than cooking bananas (P<0.05) which yielded 19 - 25.6% dry matter. Juice bananas yielded significantly more starch (19 to 25%) than cooking banana cultivars (P<0.05) which yielded (4 to 15.2% except one cultivar at 21%). Juice banana cultivars also yielded significantly more crude pectic substances (29.7 to 30.5%) than cooking banana cultivars ((7.5 to 21%) (P<0.05). Other chemical components examined included crude ash (1.97 to 4.24%), crude fibre (0.251 to 0.478%), crude protein (1.23 to 5.64%) and crude fat (0.15 to 0.58%) which did not differ significantly between cooking and juice banana cultivars (P>0.05). The physico-chemical properties (i.e. swelling power, solubility, amylose & resistant starch content and pasting
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:
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.
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

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