Daniel Ikhu-Omoregbe

A Study of the Extraction of Pectin from Dried Lemon Peels

Pectin was extracted from dried lemon peels using acid hydrolysis. Five process variables/factors were chosen for investigation; the extraction temperature, extraction time, pH, size of the peels and the peel to water mass ratio. Three response variables were monitored; the Yield (% Yield), Degree of Esterification (% DE) and Galacturonic Acid content (% GA). A duplicated 25 factorial design was conducted on dried peels. The extraction temperature, time, pH and size of the peel were found to be the most significant variables affecting the pectin yield. The most significant variable affecting the % GA was found to be the extraction time and the % DE was most significantly affected by the pH as well as the extraction temperature. A duplicated 24 design (peel size excluded as a process variable) on fresh wet peels was conducted in order to compare the results attained to those of dried peel extraction. Drying the peel therefore increased the greatest pectin yield attained, it had no drastic effect on the % GA, but it reduced the % DE of the pectin extract. A 24 design was also performed on wet peels that had been stored at atmospheric conditions for two days. The results were compared to those found from fresh wet peel extraction, in order to depict the need for drying the peel.

Parametric analysis of a high temperature pem fuel cell based microcogeneration system

This study focuses on performance analysis of a 1 microcogeneration system based on a high temperature proton exchange membrane (HT-PEM) fuel cell by means of parametric investigation. A mathematical model for a system consisting of a fuel processor (steam reforming reactor and water-gas shift reactor), a HT-PEM fuel cell stack, and the balance-of-plant components was developed. Firstly, the fuel processor performance at different fuel ratios and equivalence ratio was examined. It is shown that high fuel ratios of 0.9–0.95 and equivalence ratios of less than 0.56 are suitable for acceptable carbon monoxide content in the synthetic gas produced. Secondly, a parametric study of the system performance at different fuel and equivalence ratios using key system operating parameters was conducted. Steam-to-carbon ratio, stack operating temperature, and anode stoichiometry were varied to observe the changes in the microcogeneration system. The analysis shows that the system can reach electrical and cogeneration efficiencies of 30% and 84%, respectively.

Rheological Properties of Sunflower Oil-in-Water Emulsion Containing Vinegar, Stabilized with Gelatinized Bambara Groundnut Flour

The influence of vinegar concentrations on the rheological properties of 40% (w/w) sunflower oil-in-water emulsions stabilized with 7% (w/w) gelatinized bambara groundnut flour (BGNF) was investigated. The rheological properties of interest were steady shear, time dependent and viscoelastic characteristics. Rheological characterizations of the emulsions were carried out using a shear rate controlled rheometer. Both emulsions with and without vinegar were pseudoplastic, thixotropic and viscoelastic fluids. Vinegar however, significantly (p < 0.05) affected rheological properties of BGNF-stabilized emulsion. Presence of vinegar in the emulsion decreased extent of thixotropy, pseudoplasticity and viscoelasticity of BGNF-stabilized emulsions. The results indicated that the rheological properties of BGNF-stabilized emulsion can be controlled and manipulated using vinegar however, the presence of vinegar in BGNF-stabilized emulsion may be deleterious to the emulsion. The result provided the information to understand the influence of vinegar on the rheological properties of BGNF-stabilized emulsions for product and process development.