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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 effect of gamma irradiation and packaging on the physico-chemical 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 evaluation were administered 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 Rhodotorula). The fungal flora was predominated by Aspergillus (A. alutaceus, A. candidus, A. flavus, A. fum igat us, A. niger, A. sulphureus, A. ustus) 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 10kGy. 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 verticilloides (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. |
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