http://localhost/xmlui/handle/123456789/1292 2026-06-06T03:28:59Z http://localhost/xmlui/handle/123456789/7040 Development of Sorghum-Wheat Buns Enriched with Giant African Land Snail Meat Powder for Improved Protein among Children Aged 3-10 Years Agengo, Fredrick Benard Protein nutrition is important for human health because its deficiency results in public health problems such as Protein Energy Malnutrition (PEM). The situation is worse among children aged 3 to 10 years, a critical stage of physical development, where undernutrition results in irreversible effects, including delayed physical and cognitive development, as well as increased risk of infections and even mortality. Formulating cereal-based diets enriched with animal protein has been proposed as the most practical strategy to improve the nutritional quality of the diet. Buns are appropriate food vehicles because of their popularity among all age groups in rural and urban settlements due to their attractive features, including good eating quality, low cost, varied taste, and relatively long shelf-life. The main objective of this study was to formulate and develop sorghum-wheat buns enriched with snail meat powder for improved protein intake. Buns were prepared by replacing part of the sorghum-wheat flour with 5, 10, 15, 20, and 25% of SMP. Physical properties of volume, density, baking loss, yield, weight, hardness, and colour, proximate analyses including moisture, crude protein, crude fat, crude fibre, and ash, and mineral composition of iron, zinc, calcium, copper, and magnesium were determined for the buns. In vitro protein digestibility was tested using a single-enzyme assay with pepsin, whereas plate count agar and potato dextrose agar were used to enumerate the fungal and bacterial flora contaminating the buns during storage. Shelf-life determination for the buns was based on the number of days before the production of off-flavours and the presence of a fungal infestation. The protein nutritional quality of buns was evaluated on a Complete Randomized Design (CRD) with diets as treatments. Rats were randomly assigned to groups based on weight, forming the blocks, and each treatment was replicated three times within each block. Male weanling albino rats (Sprague Dawley) were used to determine the indices of PER, FER, NPRR, APD, and TPD. Bun amino acid efficiency was calculated using PDCAAS and DIAAS. Descriptive sensory and consumer acceptability with children followed RCBD that evaluated six variations of buns as treatments, which were randomized and replicated thrice with panelists as units and sessions as blocks. The adult consumer studies were based on the CRD approach. Randomized three-digit codes were assigned to the bun for blinding purposes, with sample arrangement on trays randomized for each panelist. The evaluation process was also randomized, with evaluators coming to the evaluation room at random to evaluate samples for acceptability. A descriptive panel was used to characterize the buns, and a consumer panel for acceptability using a 7-point facial scale with school children of 8-9 years old. Compositing with SMP progressively improved the buns' density, baking loss, yield, weight, and texture. Protein, fat, ash, energy, iron, zinc, calcium, magnesium, and copper were also increased. Enriching buns with between 5% and 25% SMP improved in-vitro protein digestibility. The maximum bacterial count in buns was below the International Microbiological Standard recommended units for dry and ready-to-eat foods of 103 cfu/g. Enriching with SMP also significantly (P<0.05) enhanced protein efficiency ratio from 0.21% to 2.70%, food efficiency ratio from 0.02% to 0.27%, apparent protein digestibility from 81.17% to 88.28%, and true protein digestibility from 87.48% to 95.38%. Protein digestibility corrected amino acid score, and the digestible indispensable amino acid score increased from 45% to 78% and 44% to 69%, respectively, in unenriched buns to buns enriched with 25% SMP. Principal Component Analysis (PCA) revealed 99% total variation of 23 attributes for buns scored by a descriptive sensory panel, of which 98% was due to the proportion of SMP that replaced sorghum-wheat composite flour in buns, and the remainder 1% was due to the buns’ physical appearance. Compositing sorghum-wheat buns with SMP imparts positive consumer attributes of fine crumb, sponginess, and crumby texture. Positive sensory score by school children of 8 to 9 years old for enriched buns was sustained throughout the three consumption sessions. The data obtained in this study indicate that incorporation with SMP imparted positive sensory characteristics associated with buns to the sorghum-wheat buns, and acceptance of such buns may be sustained over an extended period. Compositing sorghum-wheat flour with SMP is beneficial in formulating buns with superior protein and mineral quality in proportion to the amount of SMP added. Enriching with SMP also imparts positive physical characteristics of higher density, yield, and weight, reduces bun hardness and baking loss, and promotes better-keeping quality. In addition, enriching only at 5% with SMP significantly improved in vitro protein digestibility by 29% compared to the control. Enriching with SMP significantly promotes growth in rats, improves net protein retention, protein retention ratio, true protein digestibility, and protein digestibility corrected amino acid score of the sorghum-wheat buns to levels considered potential for use as supplementary or rehabilitation diets. Buns enriched at 25% with SMP have protein quality that promotes catch-up growth in emaciated rats, as assessed by the PER. Therefore, has the potential to alleviate PEM among children in developing countries. Doctor of Philosophy in Food Science and Nutrition 2026-05-28T00:00:00Z http://localhost/xmlui/handle/123456789/7022 Physicochemical, Functional Properties of Edible Insects’ Chitin and Antimicrobial Properties of Derivatives Produced Through In Vitro Chitin Digestion and Fermentation Ndiritu, Alex Karuiru Globally and in Kenya, there is a concerted effort to promote the consumption of edible insects. However, chitin poses a challenge to the utilization of edible insects as human food, since it is not digestible by the human gut's natural enzymes. Thus, the diverse biodiversity of edible insects offers a considerable chitin resource, prompting scientific investigations into its comprehensive benefits and potential applications. Therefore, this study aimed to characterize chitin extracted from House cricket (Acheta domesticus), field cricket (Gryllus bimaculatus) and black soldier fly larvae cocoons (Hermetica illucens) and to evaluate its potential health-promoting properties through in vitro digestion and fermentation studies. Chitin was chemically extracted and the functional groups were determined by Fourier Transform Infrared Spectroscopy (FTIR). The surface morphology of the chitin was examined using a Scanning Electron Microscope. Solubility, emulsion capacity, water holding capacity (WHC), oil binding capacity (FBC), degree of deacetylation (DDA) and purity of the extracted chitin were also determined. The extracted chitin was then in vitro digested by enzymes, followed by fermentation using ABY 10 and ABT 5 probiotic cultures. Derivatives of the in vitro digestion and fermentation process were then tested for antioxidant and antimicrobial properties. Further derivatives of in vitro digestion and fermentation were then determined as follows: fatty acid composition was determined using Gas Chromatography Mass Spectrometry (GCMS) while chitosan, chito-oligosaccharides, antimicrobial peptides and vitamins were determined using High Performance Liquid Chromatography (HPLC), Liquid Chromatography Mass Spectrometry (LCMS) and UltraViolet- Visible Spectroscopy (UV-VIS). Data analysis was done using STATA version 12. Data were subjected to one-way ANOVA to determine the differences in functional properties among the chitin samples. Further data were subjected to three-way ANOVA to determine the effects of the chitin sample, fermentation time and sample concentration on antioxidant activity, antimicrobial activity, fatty acid composition, chitosan, chito-oligosaccharides, antimicrobial peptides and vitamin content. The extracted chitin showed the characteristic functional groups i.e., O-H stretch, C=O stretch, N-H bend, CH2 ending and CH3 deformation, C-N stretch and C-O-C stretch. Chitin extracted from Gryllus bimaculatus recorded the highest values in oil absorption capacity (780.14%), emulsion capacity (65.67%) and emulsion stability (65.67%) (p<0.001). Chitin extracted from Acheta domesticus was more soluble in water than the commercial chitin. The highest level of deacetylation was reported in Hermetia illucens chitin (66.2%), while Acheta domesticus chitin had the least value (47.1%) (p<0.001). The microstructure images showed the presence of pores and fibers in all the chitin samples. The highest antioxidant activity in chitin samples fermented using ABY 10 was observed in derivatives of Gryllus bimaculatus, Acheta domesticus and Hermetia illucens chitin digested in vitro and fermented for 48 hours at a concentration of 5mg/ml (61.11%, 63.88% and 61.63%), while the least antioxidant activity was observed in the negative control (p<0.05). Derivatives obtained after in vitro digestion and fermentation of the chitin samples exhibited significantly different antimicrobial activity against Escherichia coli, Vibrio cholerae, Bacteroides fragilis, Enterobacter agglomerans, Shigella dysenteriae, Staphylococcus aureus and Bacillus cereus. The antimicrobial activity of the derivatives increased with an increase in fermentation time and sample concentration, with the highest activity being observed after 48 hours of fermentation and at a concentration of 10 mg/ml. The predominant SCFA in all the samples was acetic acid (40.86% - 64.75%), followed by propionic acid (8.76% - 17.34%), then butyric acid (7.51% - 15.33%) as well as trace levels of 4-methylvaleric acid (1.01% - 3.88%), iso- valeric acid and valeric acid. The highest values of chitosan were obtained after fermentation of Acheta domesticus chitin using ABY 10 and ABT 5 for 48 hours (2.91 g/100g and 2.90 g/100g) and fermentation of Hermetia illucens indigestible chitin using ABY 10 for 48 hours (2.90 g/100g) (p<0.05). Gryllus bimaculatus indigestible chitin fermented using ABY 10 for 48 hours and Acheta domesticus indigestible chitin fermented using ABY 10 and ABT 5 for 48 hours had the highest chito-oligosaccharides yield (9.82 mg/g, 9.07 mg/g and 9.37 mg/g). Gryllus bimaculatus indigestible chitin fermented using ABY10 for 48 hours, Acheta domesticus and Hermetia illucens indigestible chitin fermented using ABY 10 for 48 hours yielded the highest defensin like AMP (19.40 mg/100g and 18.32 mg/100g). Gryllus bimaculatus indigestible chitin fermented using ABY 10 for 48 hours yielded the highest vitamin B12 content (5.74 mg/100g). In conclusion, the edible insect’s chitin was similar to commercial chitin in regards to the FTIR spectra as well as surface morphology. ABY 10 proved to be more efficient in fermentation while Hermetia illucens indigestible chitin was more fermentable as compared to all the other samples. Regarding fermentation time 48 hours was found to be optimal in producing metabolites that had highest antimicrobial activity. The study findings collectively suggest that the development of chitin based food products could promote gut health. PhD in Food Science and Nutrition 2026-05-28T00:00:00Z http://localhost/xmlui/handle/123456789/7013 Physicochemical, Nutritional and Functional Properties of Popped Finger Millet (Eleusine coracana) and its Application in Product Development Koros, Clarice Jepchirchir Finger millet (Eleusine coracana) is a highly nutritious grain with significant health benefits; however, its traditional processing methods have not been fully optimized for modern applications to enhance commercialization. This study evaluated the physicochemical, nutritional, and functional properties of popped finger millet and its application in cereal bar development. Finger millet grains were sourced from Jamhuri Market in Thika Town. The grains were sorted, cleaned, and dried, with an initial moisture content of 10.01%. The moisture content was subsequently adjusted to 15%, 18%, and 21% (in triplicates) and popped at chamber pressures of 120, 140, and 160 psi. The popped grains were analyzed for selected physicochemical, nutritional, functional, and microstructural properties. Grains popped at 21% moisture content and 160 psi were used to formulate five cereal bar variants with varying concentrations of guar gum and honey, which were then subjected to sensory, physicochemical, and microbiological analyses. Results indicated that increasing moisture content and pressure significantly (p≤0.05) enhanced popping yield and expansion ratio while reducing bulk density. The interaction between pressure and moisture content also had a significant (p≤0.05) effect on these parameters. Increasing moisture content from 15% to 21% significantly (p≤0.05) increased lightness and total color difference, while redness and browning index decreased significantly with increasing moisture content and pressure. Crude fat and moisture content of the popped grains decreased significantly (p≤0.05) with increasing pressure and moisture, whereas crude protein content increased significantly with pressure. Mineral analysis showed significant (p≤0.05) increases in zinc and iron content with increasing pressure and moisture levels. Total phenolic content also increased significantly, while phytates and tannins decreased significantly (p≤0.05), indicating improved nutritional quality. Functional properties were significantly influenced by processing conditions, with water absorption capacity, swelling power, and viscosities increasing, while bulk density decreased when popping pressure and moisture content were raised. Particle size distribution was also significantly affected by pressure, moisture, and their interaction. For the developed cereal bars, color attributes (lightness, redness, yellowness, and hue angle) varied significantly (p≤0.05), with increased lightness and yellowness observed at higher honey levels (10%–50%). Water activity ranged from 0.391 to 0.776 and decreased with increasing honey concentration, remaining within safe microbial limits. Bulk density and texture decreased significantly (p≤0.05) with increasing honey levels, improving handling and packaging characteristics. Proximate composition showed moisture content ranging from 3.47% to 11.35%, crude fiber from 2.31% to 2.70%, crude protein from 7.17% to 8.39%, and carbohydrates from 70.02% to 78.24%, all significantly influenced by formulation. Microbial analysis of the developed cereal bars revealed total viable counts ranging from 2.2007 to 2.7253 log CFU/g, within acceptable limits for ready-to-eat foods. No coliforms were detected, indicating satisfactory hygienic practices. Staphylococcus aureus was detected in two cereal bars, although no immediate health risk was indicated, while yeast and mold counts remained within acceptable limits. Sensory evaluation showed significant differences (p≤0.05) in appearance, flavor, taste, texture, and overall acceptability. Samples B1 and B5 were the most preferred, with overall acceptability scores above 7.0. Honey and guar gum significantly influenced sensory attributes, with higher honey levels enhancing flavor and consumer acceptance. In conclusion, popping pressure and moisture content significantly affect the nutritional, functional, and physicochemical properties of finger millet and demonstrates strong potential for value addition. The developed cereal bars exhibited acceptable sensory and microbial quality, supporting their potential as nutritious snack products. These findings highlight the role of popped finger millet in enhancing food and nutrition security and promoting the utilization of this underutilized indigenous crop. MSc in Food Science and Technology 2026-05-26T00:00:00Z http://localhost/xmlui/handle/123456789/7004 Assessment of the Sources and Hydrological Impacts of Best Management Practices on Pollutants Flow Using SWAT in Nyangores River of Upper Mara Basin, Kenya Kigira, Francis Karanja The Nyangores River watershed, located in Kenya's upper Mara Basin has challenges of rivers degradation, where increased non-point source pollution has caused water quality issues. The objectives were identify the key sources of pollutants, calibrate and validate the SWAT model for streamflow, sediment, and nutrient transport and to assess the impact of various Best Management Practices (BMPs) on nutrient and sediment loads. Data collection followed: gathering hydro-climatic data for model calibration, field observations, collecting samples and laboratory analysis. Impacts of various BMP scenarios on water quality were modelled, focusing on riparian buffer zones, reforestation, and contour farming. Calibration and validation with indicators such as the Nash-Sutcliffe Efficiency (NSE) and R² was done for reliability. Parameters tested, Ph., Ec, Nitrates, Phosphates and Total suspended solids (TSS).Nitrogen levels in the river exceeded safe limits by 50%, with average concentrations of 3.2 mg/L, while phosphorus levels were recorded at 1.1 mg/L, surpassing the eutrophication rate which is TP 0.05mg/L and TN 1.0mg/L. Sedimentation contributed to a 35% increase in total suspended solids (TSS), with average TSS levels measured at 210 mg/L, particularly in areas with steep slopes and poor soil conservation practices. The SWAT model was calibrated using streamflow data from 2003-2008, and the calibration process achieved satisfactory results, with a Nash-Sutcliffe Efficiency (NSE) of 0.72 and an R² value of 0.75. During validation, the model performance well with an NSE of 0.70 and an R² of 0.73 for the validation period (2009-2013) demonstrating the effectiveness of the model. Nitrogen and phosphorus was reduced by 38% and 42% in simulation. In conclusion, this research demonstrates the SWAT model's efficacy in Nyangores watershed, advocating for sustainable land management practices to mitigate water pollution and emphasizing the importance of preserving natural ecosystems for water quality protection. The study recommends preserving natural forests as they effectively control pH, electrical conductivity, nitrates, and phosphates compared to grasslands. Management practices, such as filter strips and contouring, resulted in reduced sediment yields. Public awareness on the importance of management practices and riparian vegetation is paramount. PhD in Soil and Water Engineering 2026-05-21T00:00:00Z