Browsing by Author "Ofosu, D.O."

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Determination of the elemental composition of the pulp, seed and fruit coat of black velvet tamarind (Dialium guineense) using instrumental neutron activation analysis
(Research Journal of Applied Sciences, Engineering and Technology, 2013-10) Ofosu, D.O.; Opata, N.S.; Gyampo, O.; Odamtten, G.T.
This study sought to provide data on the mineral composition of the fruit pulp, outer coat and seed of Dialiu guineense in an attempt to widen the sources of minerals for the rural population of sub-Saharan Africa. The elemental composition of the pulp, seed and fruit coat of black velvet tamarind (Dialium guineense) was determined using Neutron Activation Analysis. The fruit pulp contained manganese (23.40±1.57μg/g), chlorine (205.40±37.59 μg/g), calcium (5671.00±2132.30 μg/g), sodium (332.95±8.76 μg/g) and potassium (6190.00±711.85 μg/g). The seed and fruit coat contained all these minerals except potassium and sodium respectively. The fruit pulp can serve as a good source of macrominerals for humans while the fruit coat and seed could be ground and incorporated in various meal formulations of livestock as mineral supplements.
Effects of irradiation on physical and sensory characteristics of cowpea seed cultivars (Vigna unguiculata L. Walp)
(Radiation Physics and Chemistry, 2012-01) Ocloo, F.C.K.; Darfour, B.; Ofosu, D.O.; Wilson, D.D.
Cowpeas (Vigna unguiculata L. Walp) are leguminous seeds widely produced and consumed in most developing countries of sub-Saharan Africa where they are a good source of affordable proteins, minerals and vitamins to the mainly carbohydrate-based diet of sub-Saharan Africa. At storage cowpea may be attacked by insects that cause severe damage to the seeds. The objective of this study was to investigate the effects of gamma irradiation on some physical and sensory characteristics of cowpea seed cultivars. Four cowpea cultivars were irradiated with gamma radiation at dose levels of 0.25, 0.50, 0.75, 1.0 and 1.5 kGy. Moisture content, thousand grain weight and bulk densities were determined as well as the amount of water absorbed during soaking and some sensory characteristics were equally determined. All the physical parameters studied were not significantly (p>0.05) affected by the radiation. There was no significant (p>0.05) effect of the radiation on the sensory attributes like flavour, taste, texture, softness and colour of the cowpea seeds. Similarly, the radiation did not affect significantly (p>0.05) the acceptability of the treated cowpea cultivars. © 2011 Elsevier Ltd.
Physical, proximate, functional and pasting properties of flour produced from gamma irradiated cowpea (Vigna unguiculata, L. Walp)
(Radiation Physics and Chemistry, 2012-04) Darfour, B.; Wilson, D.D.; Ofosu, D.O.; Ocloo, F.C.K.
Cowpeas are leguminous seeds widely produced and consumed in most developing countries of sub Saharan Africa. The aim of this study was to determine the physical, proximate, functional and pasting properties of flour obtained from gamma irradiated cowpea. Four cowpea cultivars were irradiated with gamma radiation at dose levels of 0.25, 0.5, 0.75, 1.0 and 1.5. kGy with the unirradiated cultivars serving as controls. The samples were hammer milled, sieved and stored at 4. °C for analysis. Physical, proximate, functional, pasting properties were determined using appropriate methods. In general, the irradiation dose applied to cowpea for insect control did not significantly affect the physical and proximate properties of the flour. However, significant increase (p<0.05) was achieved in paste bulk density, water and oil absorption capacities, foam capacities and least gelation concentrations of flour in general, which may be attributed to the irradiation. The radiation reduced the swelling power and water solubility index significantly. The peak temperature, peak viscosity and setback viscosity of the pastes were significantly (p<0.05) reduced while breakdown viscosity was significantly (p<0.05) increased by the radiation. It was established that the doses used on cowpea affected both the functional and pasting properties of the flour. © 2011 Elsevier Ltd.
Radiation Preservation of Black Velvet Tamarind (Dialium guineense Wild.)
(University of Ghana, 2010-12) Ofosu, D.O.
The economic distribution and marketing of the lesser known fruit Dialium guineense Wild in Ghana has been studied using a structured questionnaire and the rapid appraisal system. The seasonality of the fruit (from January to May) makes it abundant in the peak season and rare or not all for the best part of the year. Some fruits also go to waste in the field owing to underexploitation. This thesis provides information on the resident fungi, mycological quality, sorption isotherm, and the e ffect 0 f gamma irrad iation and packaging on the phys ico-chem ical properties of the fruit and the sensory evaluation of the pulp by a taste panel with the view to showing the economical and nutritional potential of the fruit. The resident fungi and mycological quality were assessed by the conventional decimal serial dilution technique and plating on three media (PDA, DG 18 and OGYE). Sorption isotherms at 29±J -c were determined under simulated Environmental Relative Humidity (20, 55, 65, 75, 85, 95%) provided by glycerol: water mixtures; physico-chemical properties were assessed by the method of the Association of Official Analytical Chemists. Descriptive and preference sensory eval uation were adrn inistered using prescribed international methods on a hedonic scale. The tamarind markets are in the southern sector of the country, namely Greater Accra, Eastern, Central, Ashanti and Volta Regions with the hub at Ho, Abor and Akatsi in the Volta Region. The local names of the fruit varied from one region to another. The fruit was purchased mostly by adult females (48.25%) followed by school children (37.06%) and adult males (14.68%). The produce is marketed predominantly in polypropylene sacks (81.81 %) with jute sack taking only 3.63% of the packaging. The sizes of the fruit as expected were variable. The pulp did not lose moisture at 75% ERH but lost moisture to the surrounding at ERI-I's 20, 55, and 65% and the same was true for the whole (intact) fruit. The resident fungi in the pulp belonged to 15 fungal species and 7 genera (Aspergillus, Candida, Cladosporium, Fusarium, Penicillium, Neurospora and Rhodotorulai. The fungal flora was predominated by Aspergillus (A. alutaceus, A. candidus, /I. flavus, A. fum igat us, A. niger, A. sulphureus, A. us/us) followed by Penicillium (P. digitatum, P. expansum) all of which are being recorded for the first time in the fruit of D. guineense. The fruits were also infested with an insect, Ephestia cautella, of economic importance. There was a commensurate drastic reduction in the mould count in the fruit as the irradiation dose increased from 0 to IOkGy. The resident fungi were not however completely eliminated with the variable residual species appearing after 3 months storage in the packaging materials (polypropylene, polyethylene and jute). The presence and isolation of mycotoxinproducing species A. flavus (Aflatoxins), A. alutaceus (Ochratoxins), P. expansum, P. digitatum (Patulin), F verticil/oides (fumonisin) leave much to be desired. Packaging did not significantly influence pH and ash content; but influenced total titratable acidity with increasing dose and storage time. The crude fat content decreased with prolonged storage and increasing dose of gamma irradiation while there was no interaction between dose applied, packaging material and storage time. The panelists did not find significant (P>0.05) difference in the parameters tested for acceptance (colour, sweetness, acidity and tenderness) and they found no differences in the packaging material although they slightly preferred produce kept in jute sacks. The practical implications of these findings are discussed in the light of future promotion and preservation of the pulp for industrial use after gamma irradiation.