Masters Degree Dissertations

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12504/107

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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(Kyambogo University [unpublished work], 2023-10) Bwamiki, Lydia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.
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.
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.

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Browsing Masters Degree Dissertations by Subject "Cassava"