Research Papers

Towards Enhancement of JKUAT-PAUSTI Research and Innovation Capacity

Fri, 07 Feb 2025 00:00:00 GMT

Towards Enhancement of JKUAT-PAUSTI Research and Innovation Capacity Prof. Sila, Daniel Ndaka; Prof. Koaze, Hiroshi The presence of antinutrients in common beans negatively affects mineral bioavailability. Therefore, this study aimed to predict the antinutrient to mineral molar ratios (proxy-indicators of in vitro mineral bioavailability) of a wide range of raw bean types, using near-infrared (NIR) spectroscopy. Iron, zinc, phytate and tannin concentrations and, antinutrient to mineral molar ratios were determined. Next, model calibration using NIR spectra from milled beans was performed. This entailed wavelength selection, pre-processing and partial least squares regression. Bean type had a significant effect on tannin content. The average values of phytate to iron (Phy:Fe), phytate to zinc (Phy:Zn), tannins to iron (Tan:Fe) and phytate and tannins to iron (Phy + Tan:Fe) MRs were 27.6,61.7, 16.0 and 43.6, respectively. With determination coefficients for test set prediction above 75%, the PLS-R models for Phy:Zn, Tan:Fe and Phy + Tan:Fe molar ratios are useful for screening purposes. Key Words: Common beans, Near-infrared spectroscopy, Antinutrients, Minerals, Molar ratios Abstracts of Scientific Publications: April 2020 to Februry 2022, April 2022

Towards Enhancement of JKUAT-PAUSTI Research and Innovation Capacity

Fri, 07 Feb 2025 00:00:00 GMT

Towards Enhancement of JKUAT-PAUSTI Research and Innovation Capacity Prof. Sila, Daniel Ndaka; Prof. Koaze, Hiroshi The effect of temperature reconditioning on cold-stored potato tubers was investigated for three popularly consumed potato varieties (Shangi, Unica, and Dutch robjin) grown in Kenya. The potatoes were stored at 4 °C for 30 days, followed by removal and storage at 22 ± 3 °C for 9 days during which changes in sugar concentration were evaluated every two days. In parallel, potato chips and French fries were processed, and their colors were determined. The results showed that sugar content decreased significantly with increasing reconditioning time. The relative decrease in fructose content was the highest (p < 0.05) in Dutch robjin (57.49%), followed by Shangi (49.22%) and Unica (38.18%). Glucose content decreased by 54.1% in Dutch robjin, 49.5% in Shangi, and 50.8% in Unica. The lightness (L*) of French fries and chips increased significantly (p < 0.05) with reconditioning time while the redness (a*) values decreased significantly (p < 0.05) across all varieties. The correlation between lightness and the total reducing sugar content of the potatoes was r < −0.93, indicating a strong negative correlation for both products. The coefficient of determination showed that the glucose content of the tubers accounted for 80.5–97.6% of the lightness of French fries and 88.4–94.2% for potato chips. The critical glucose content range for acceptable products in French fries and chips based on the color (L* and a*) values was 12–22 mg/100g and 8–14 mg/100g, respectively, for the varieties in this study. Key Words: potato; storage; sugars; reconditioning; cold storage Abstracts of Scientific Publications: 2023-2024, April 2024

Towards Enhancement of JKUAT-PAUSTI Research and Innovation Capacity

Fri, 07 Feb 2025 00:00:00 GMT

Towards Enhancement of JKUAT-PAUSTI Research and Innovation Capacity Prof. Sila, Daniel Ndaka; Prof. Koaze, Hiroshi Doum palm (Hyphaene compressa) is an enduring member of the Arecaceae family of plants, an essential multipurpose plant with exceptional features that serve as a socioeconomic resource for people in the East Africa region. The unavailability of genetic and genomic data leads to 3 difficulties enhancing such a crop, thereby preventing the actualization of its agronomic and breeding potential, hence the need for characterization. This study included 64 genotypes of doum palm collected from four locations in Kenya and ten polymorphic chloroplast microsatellite markers. Locus Among the ten polymorphic cpSSRs studied, the OPCG13 locus exhibited the highest observed and expected heterozygosity. Across all loci, we detected the mean value of 10.145 for the gene flow parameter. The mean number of significant allele frequencies for the 79 alleles detected was 0.75, with a range of 0.531 to 0.89. The median was 0.0036, 0.341, and 0.275 for observed heterozygosity, predicted heterozygosity, and PIC, respectively. All 64 genotypes were sorted into three main categories using neighbor-joining clustering and STRUCTURE analysis. At the population level, PCoA analysis explained 51.66 percent of the variation. As a result of these findings, cpSSR markers were used for the first time to characterize selected doum palm germplasm, which signifies that such a marker helps study doum palms at the molecular level. Our findings indicate that doum palm species in Kenya have a reasonable genetic variation coupled with considerable heterozygosity; consequently, these doum palm genetic variations are essential for the genetic improvement, breeding, and conservation initiatives of doum palm genotypes in Kenya. Key Words: Doum palm (Hyphaene compressa), Rural pastoralists, Arid and semi-arid Kenyans, Chloroplast SSR (cpSSR), Genetic diversity, Molecular characterization. Abstracts of Scientific Publications: 2022-2023, April 2023

Towards Enhancement of JKUAT-PAUSTI Research and Innovation Capacity

Fri, 07 Feb 2025 00:00:00 GMT

Towards Enhancement of JKUAT-PAUSTI Research and Innovation Capacity Prof. Sila, Daniel Ndaka; Prof. Koaze, Hiroshi The effect of iron-doped cerium oxide (FeCeO2) nanoparticles as a fuel additive was experimentally investigated with waste cooking oil methyl ester (WCOME) in a four-stroke, single cylinder, direct injection diesel engine. The study aimed at the reduction of harmful emissions of diesel engines including oxides of nitrogen (NOx) and soot. Two types of nanoparticles were used: cerium oxide doped with 10% iron and cerium oxide doped with 20% iron, to further investigate the influence of the doping level on the nanoparticle activity. The nanoparticles were dispersed in the tested fuels at a dosage of 90 ppm with the aid of an ultrasonic homogenizer. Tests were conducted at a constant engine speed of 2000 rpm and varying loads (from 0 to 12 N.m) with neat diesel (D100) and biodiesel–diesel blends of 30% WCOME and 70% diesel by volume (B30). The engine combustion, performance, and emission characteristics for the fuel blends with nanoparticles were compared with neat diesel as the base fuel. The test results showed improvement in the peak cylinder pressure by approximately 3.5% with addition of nanoparticles to the fuel. A reduction in NOx emissions by up to 15.7% were recorded, while there was no noticeable change in unburned hydrocarbon (HC) emissions. Carbon monoxide (CO) emission was reduced by up to 24.6% for B30 and 15.4% for B30 with nano-additives. Better engine performance was recorded for B30 with 20% FeCeO2 as compared to 10% FeCeO2, in regard to cylinder pressure and emissions. The brake specific fuel consumption was lower for the fuel blend of B30 with 10% FeCeO2 nanoparticles, in low-to-medium loads and comparable to D100 at high loads. Hence, a higher brake thermal efficiency was recorded for the blend in low-to-medium loads compared to D100. Keywords: Waste cooking oil methyl ester; iron-doped cerium oxide nano-particles; diesel engine; combustion characteristics; emission characteristics Abstracts of scientific publications: 2019-2020