DSpace Collection:http://41.89.96.81:8080/xmlui/handle/123456789/6492024-03-27T23:26:20Z2024-03-27T23:26:20ZEffects of post tanning operations and aloe barbadensis miller-Carrageenan mixture on physical, structural and chemical properties and on hexanvalent chromium formation in leatherNalyanya, Kallen Mulilohttp://41.89.96.81:8080/xmlui/handle/123456789/33332024-03-14T13:36:52Z2019-05-01T00:00:00ZTitle: Effects of post tanning operations and aloe barbadensis miller-Carrageenan mixture on physical, structural and chemical properties and on hexanvalent chromium formation in leather
Authors: Nalyanya, Kallen Mulilo
Abstract: Leather industry is a key player in most developing countries’ economy. However, its tanning process has been associated with environmental and human health hazards due to formation of Cr (V I). To address these concerns, this study investigated effects of Aloe barbadensis Miller (ABM) mixed with carrageenan and of crusting operations on physical and structural properties, and elemental concentrations and on formation of Cr (VI) in leather crusts. Raw cow hide was conventionally processed to tanning, retanning, dyeing and fatliquoring and after each step, samples were cut for testing and others treated with ABM mixed with carrageenan. Results from the Instron tester showed that all the crusting operations significantly affect both physical and organoleptic properties of leather. Confocal Raman spectroscopic data showed that crusting operations and the incorporation of ABM and carrageenan causes structural alterations as indicated by shifls in peak positions and variations in intensities especially of amide bands. Predicted strength properties using empirical models and equations showed closer agreement with experimental data. The ideal quantity of ABM was calculated to be 3.78% and the incorporation stage done at fatliquoring process. Interaction of ABM/carrageenan is only majorly physical with minor interactions involving hydroxyl bonds and sulphur. Results from EDXRFs showed that the incorporation increases the levels of S, K, Ca, V, Fe and Zn. All the crusting processes affect the levels of Cr (VI) formed in both aged and non-aged leather crusts. The levels of Cr (VI) in leathers is detectably higher in retanned and fatliquored and minimum in dyed crusts. The levels of Cr (VI) in leather crusts processed with ABM Miller and carrageenzm, aged and unaged, were below detection level. ABM and carrageenan have shown total inhibition of Cr (VI) formation. For purposes of crosslinking and improving the physical properties, flie study recommends the incorporation process to be done during pretanning operations. However, for antioxidant purposes, the incorporation should be done afier tanning process especially fatliquoring stage and at most 3.784 wt % of the ABM and carrageenan used. The study recormnends more research to determine the ideal particle sizes of the ABM and carrageenan molecules to enhance the penetration and distribution within the matrix. The study suggests activation of the ABM and carrageenan by sulphiting for improved wetting and adhesion. More appropriate coupling agents need to be determined for adhesion and wetting back2019-05-01T00:00:00ZEffects of post tanning operations and aloe barbadensis miller-carrageenan mixture on physical, structural and chemical properties and on hexavalent chromium formation in leatherNalyanya, Kallen Mulilohttp://41.89.96.81:8080/xmlui/handle/123456789/33252024-03-06T11:38:57Z2019-05-01T00:00:00ZTitle: Effects of post tanning operations and aloe barbadensis miller-carrageenan mixture on physical, structural and chemical properties and on hexavalent chromium formation in leather
Authors: Nalyanya, Kallen Mulilo
Abstract: Leather industry is a key player in most developing countries’ economy. However, its tanning process has been associated with environmental and human health hazards due to formation of Cr (VI). To address these concerns, this study investigated effects of Aloe barbadens isMi1ler (ABM) mixed with carrageenan and of crusting operations on physical and structural properties, and elemental concentrations and on formation of Cr (VI) in leather consists. Raw cow hide was conventionally processed to tanning, re-tanning, dyeing and fatliquoring and after each step, samples were cut for testing and others treated with ABM mixed with carrageenan. Results from the Instron tester showed that all the crusting operations significantly affect both physical and organoleptic properties of leather. Confocal Raman spectroscopic data showed that crusting operations and the incorporation of ABM and carrageenan causes structural alterations as indicated by shifts in peak positions and variations in intensities especially of amide bands. Predicted strength properties using empirical models and equations showed closer agreement with experimental data. The ideal quantity of ABM was calculated to be 3.78% and the incorporation stage done at fatliquoring process. Interaction of ABM/carrageenan is only majorly physical with minor interactions involving hydroxyl bonds and sulphur. Results from EDXRFs showed that the incorporation increases the levels of S, K, Ca, V, Fe and Zn. All the crusting processes affect the levels of Cr (VI) formed in both aged and non-aged leather crusts. The levels of Cr (VI) in leathers is detectably higher in retanned and fatliquored and minimum in dyed crusts. The levels of Cr (VI) in leather crusts processed with ABM Miller and carrageenan, aged and unaged, were below detection level. ABM and carrageenan have shown total inhibition of Cr (VI) formation. For purposes of cross linking and improving the physical properties, the study recommends the incorporation process to be done during pretanning operations. However, for antioxidant purposes, the incorporation should be done after tanning process especially fatliquoring stage and at most 3.784 wt % of the ABM and carrageenan used. The study recommends more research to determine the ideal particle sizes of the ABM and carrageenan molecules to enhance the penetration and distribution within the matrix. The study suggests activation of the ABM and carrageenan by sulphiting for improved wetting and adhesion. More appropriate coupling agents need to be determined for adhesion and wetting back.2019-05-01T00:00:00ZDevelopment of protein enriched maize - cassava leaf composite extruded instant porridge flourTerefe, Zemenu Keriehttp://41.89.96.81:8080/xmlui/handle/123456789/31742024-01-12T08:18:47Z2022-10-01T00:00:00ZTitle: Development of protein enriched maize - cassava leaf composite extruded instant porridge flour
Authors: Terefe, Zemenu Kerie
Abstract: Food insecurity and malnutrition especially protein deficiency is a major public health problems in developing countries. The aim of this study was, therefore to develop protein- enriched extruded instant porridge flour using composite flour of maize and cassava leaf through microbial fermentation and extrusion cooking technology. Microbial fermentation using starter cultures of Lactobacillus plantarum, Saccharomyces cerevisiae and their co- cultures were used particularly to assure the safety of ingredients. Hence, these starter cultures showed a significant improvement in the nutritional qualities of maize flour and cassava leaves by reducing the anti-nutritional factors, particularly the hydrogen cyanide level in cassava leaves below the threshold limit (HCN < 10 mg/kg). Response Surface Methodology (RSM) in Box-Behnken design was used for formulation and optimization of the process variables for the production of protein-enriched instant flour. There was a significant (p < 0.001) increase in the protein and essential amino acid contents of the extruded flour due to the supplementation of maize with cassava leaf flour. The optimum extrusion variables that could give an optimum proximate composition and essential amino acid profiles were at extrusion temperature (ll8°C), feed composition (8%) and feed moisture (14%) with composite desirability of 99.8 per cent. The water solubility index showed a significant (p < 0.05) positive correlation between in vitro protein digestibility and mineral contents. In vitro protein digestibility was significantly (p < 0.05) increased by extrusion temperature and feed composition. The descriptive panel developed a lexicon of l2 attributes to profile the product‘s appearance, aroma, flavour, taste and texture. In comparison to the control, the inclusion of cassava leaf flour increased the intensity of bittemess by up to 59% and the number of specks by up to 46%. The control sample had the highest consumer acceptability score for all the attributes followed by instant porridge developed at a feed composition of 5%, feed moisture of 14% and extrusion temperature of 100°C. Paper packaging material had higher scores for desirable attributes such as overall aroma and sweetness while low-density polyethylene had a higher score for undesirable attributes such as bitterness and rancid off-flavours. Production of protein-enriched foods from locally available ingredients can be an ideal solution for the ever-increasing food and nutrition insecurity particularly protein-energy malnutrition in developing countries. In this study, the use of cassava leaf and maize composite flour for the production of protein-enriched flour through the application of extrusion technology has been found ideal for protein and other micro-nutrient improvements2022-10-01T00:00:00ZSpatiotemporal variation in plasmodium falciparum transmission in Selected sites in western KenyaOduma, Colins Okinyihttp://41.89.96.81:8080/xmlui/handle/123456789/31652024-01-12T06:56:41Z2023-09-01T00:00:00ZTitle: Spatiotemporal variation in plasmodium falciparum transmission in Selected sites in western Kenya
Authors: Oduma, Colins Okinyi
Abstract: Asymptomatic malaria infections are a threat to elimination of this vector-borne infectious disease. In many endemic regions, malaria transmission is seasonal. However, the impact of seasonality on Plasmodium falciparum (P. falciparum) gametocyte levels in peripheral blood and their transmission to local mosquito vectors are not well understood. Data describing these parasitological indices across regions of varying transmission intensity is scanty. In addition, malaria transmission can vary significantly over small geographic scales, but the drivers of this heterogeneity are not well understood. This study evaluated the impact of seasonality on P. falciparum transmission potential, trends in parasitological indices across areas of differential malaria transmission, and factors that might correlate small scale variation in transmission. Blood samples were collected from individuals living in Homa Bay County (low transmission) and Kisumu County (moderate transmission) in the dry season (n=l116) and rainy season (n=l743). In addition, blood samples were collected from approximately 150 individuals in each of 20 clusters in Busia County (high transmission) in rainy season. Blood samples were screened for P. falciparum parasites using quantitative polymerase reaction (qPCR) and microscopy. In Homa Bay and Kisumu the presence and density of blood gametocytes was measured by reverse transcription PCR (RT-qPCR). Differences in parasite and gametocyte densities across seasons were determined by unpaired t-test. Differences in the prevalence, proportion of submicroscopic and gametocyte positive infections across study sites were determined by X2 test. A generalized linear mixed effect model was used to determine predictors of infections. Potential mosquito larval habitats and their number within 250 m of a household were determined by ArcMap. In Homa Bay and Kisumu, mean parasite densities did not differ in dry versus rainy season (lEO.562). Gametocyte densities were 3-fold higher in the rainy than dry season (rainy: 3.46 transcripts/uL blood, dry: 1.05 transcripts/uL, P<0.00l). Parasite prevalence and densities, and gametocyte prevalence and densities were highest in the high transmission region. In contrast, the proportion of asymptomatic submicroscopic infections was highest in the low transmission region. Proportion of gametocyte positive infections did not differ across transmission intensities. In Busia County, across the 20 clusters, 3-folds and 4-folds variation in parasites prevalence by qPCR and microscopy respectively was observed. Three to 34 larval habitats per cluster, and 0-15 habitats within a 250m radius around households were observed. Low altitude, kitchen located indoors, open eaves, a lower level of education of the household head, younger age, and being male were significant predictors of higher prevalence. The number of habitats and their proximity to households Was not a predictor for prevalence. In conclusion, parasites increase their investment in transmission in the rainy season, reflected by higher gametocyte densities. Seasonal changes of gametocytemia among infections need to be considered when designing malaria control measures. Pronounced variation in prevalence at small scales and the determinants need to be considered for malaria surveillance and control.2023-09-01T00:00:00Z