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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/11410

Title: Characterization of cocoyam (Xanthosoma sagittifolium) for increased food use
Authors: Boakye, Abena Achiaa
Issue Date: 15-Oct-2018
Abstract: Cocoyam, Xanthosoma sagittifolium, provides sustenance for over 400 million people worldwide and is the most consumed aroid in West Africa. However, there is paucity of data on its processability; it has limited existing food use, and there is lack of updated dishes to meet changing consumer needs. The aim of this study was to characterise the processing characteristics of roots/cormels, flours and starches of Xanthosoma sagittifolium varieties (red and white) in Ghana; to investigate potential uses of the flours in the development of complementary gruels, and to develop convenient versions of cocoyam eto (εtͻ), a local delicacy. Mineral composition, physicochemical, functional and cooking properties were determined by standard methods. Textural characteristics of the cormels were analysed by uniaxial compression testing. Molecular characteristics and water-starch interactions of cormels, flours and starches were investigated by low field nuclear magnetic resonance (LF-NMR) relaxometry and complemented with multispectral imaging in the analysis of the cormels. A 3-component constrained lattice mixture design was used to generate formulations from pre-gelatinised cocoyam, millet and cowpea flours in the development of infant gruels. Milk powder (15%), sugar (10%), salt (0.5%) and carrot flour (10%) were added to each formulation. Two pretreatment methods - steaming and boiling, were used in the development of the εtͻ flours. An accompanying condiment for the εtͻ was developed from freeze-dried onions, oven-dried pepper and sun-dried anchovies. Quantitative descriptive analysis and consumer evaluations of the developed products were conducted by standard methods using trained and untrained panel, respectively. A commercial ready-to-prepare gruel from maize, soyabean and peanut, and traditionally prepared εtͻ, were controls for the sensory studies on the complementary gruels and developed εtͻ samples, respectively. Cormels of both varieties had similar dry matter content, as well as physical and mechanical properties. Four fast-interacting water populations were observed in the roots during cooking. The white root variety was slightly more sensitive towards gelatinization according to LF-NMR. A strong negative correlation existed between dry matter and all multispectral wavelengths >800 nm, suggesting the potential use of that spectral region for rapid analysis of dry matter content of the cormels. Subtle differences were observed between varieties in starch content, amylose/amylopectin ratios and gelatinization characteristics. Additionally, 1-2 water populations, dependent on the temperature and concentration, were observed in the starch/flour suspensions. The starch samples showed high purity levels; 96.00% and 89.12% for red and white variety, respectively. Relaxation time measures indicated suspension concentration had stronger impact on gelatinization strength and behaviour than variety. The pasting temperatures ranged from 77.68–80.43 oC in agreement to relaxation time measurements. Both varieties had high carbohydrate (85.50- 91.45%), low fat (0.11 - 0.19%) and appreciable mineral content. Gruel formulations (F1 – F10) had protein levels of 11.31(F2) to 13.87(F1) g/100g. Formulation F2 had the highest mean overall likeness of 5.92 relative to 5.61 for the control and appreciable calorific value of 0.931 kcal/g. Consumers’ willingness to feed baby with developed products was high with mean score of 5.79 for F2. The ready-to-prepare ԑtↄ-mix from steamed cocoyam flour had highest consumer acceptance of 6.85, similar to 6.89 for the control. The study established the effectiveness of the use of applied spectroscopic methods in assessing the processing characteristics of the roots, flours and starches of cocoyam cormels. Novel products in the form of ready-to-prepare εtͻ-mix and protein-energy dense cocoyam complementary gruels with high overall acceptance were developed. The findings provide basis for further research work on the application of cocoyam in new food product development.
Description: A Thesis submitted to the Department of Food Science and Technology, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award degree of Doctor of Philosophy in Food Science and Technology, 2017
URI: http://hdl.handle.net/123456789/11410
Appears in Collections:College of Science

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