Quality changes in cocoyam flours during storage
Abstract Cocoyam tubers were subjected to two processing methods (fermentation and parboiling) and milled into flour. The samples were stored at 25°C, 35°C, and 45°C and analyzed at 2 weeks interval for 8 weeks for their nutritional, functional, and pasting properties. Data obtained were subjected to multiple analysis of variance. Storage period and its interactive effect with the processing methods had significant (P < 0.05) effects on all the nutritional composition of the flour except for the fat content. Water absorption index, wettability, and bulk density ranged from 1.94–2.72%, 25.30–135.50 sec, and 0.48–0.71 g/cm3, respectively. The entire pasting properties were significantly affected by the storage period while the interaction between storage temperature, processing methods, and storage period affected all the pasting properties except the peak time, peak, and breakdown viscosity. This study showed that processing methods storage periods and storage temperatures produced cocoyam flour with different quality characteristics.
QUALITY EVALUATION OF COCOYAM-COWPEA FLOUR BLENDS AND SENSORY ATTRIBUTES OF THEIR COOKED PASTE ( AMALA )
Cocoyam, as an indigenous starchy food crop, is a desirable vehicle in alleviating the endemic protein malnutrition in Nigeria. This study evaluated some quality attributes of cocoyam-cowpea flour blends and the sensory attributes of their cooked paste (amala). Fermented cocoyam flour (FCF) was substituted with cowpea flour (CWF) at 0 (control), 10, 20, 30, 40 and 50% levels. The proximate and mineral composition, functional and pasting properties of FCF-CWF mixtures, and sensory properties of cooked paste obtained from the mixtures were determined using standard methods. Range of values for moisture, protein, fat, ash, crude fibre and carbohydrate contents of the FCF-CWF blends were 8.88 9.40%, 6.05 14.2%, 0.72 1.76%, 3.20 3.44%, 1.86 2.46% and 69.3 78.8%, respectively. The calcium, sodium and magnesium contents of the flour blends increased with increase in CWF. The bulk density of the control sample was not significantly (p>0.05) affected by substituting with CWF. The water absorption and swelling power of the control were not significantly (p>0.05) affected by CWF up to 40% and 30% substitution levels, respectively. Apart from the peak, trough and breakdown viscosities, there was no significant (p>0.05) difference in the pasting characteristics of both control and flour blends. Substituting FCF with CWF up to 20% level did not significantly (p>0.05) affect the texture, taste and overall acceptability of the paste. An acceptable cooked paste (amala) could be produced from fermented cocoyam flour enriched with 20% cowpea flour.
Proximate and mineral composition of cocoyam (Colocasia esculenta L. and Xanthosoma sagittifolium L.) grown along the Lake Victoria basin in Tanzania and Uganda
The proximate and mineral compositions of cocoyam (Colossian esculenta L. andXanthosoma sagittifolium L) grown along Lake Victoria basin in Tanzania and Uganda were analyzed. C. esculenta and X. sagittifolium samples were significantly (p < 0.05) different in terms of their proximate composition and mineral contents regardless of their country of origin. Proximate analyses included ash, crude protein, and crude fibre. Proximate composition of cocoyam results demonstrated that X. sagittifolium variety is nutritionally superior to that of C. esculenta. Minor nutrients measured were calcium, magnesium, copper, iron, sodium, zinc, manganese, and potassium. The results from these analyses demonstrate that the proximate composition of cocoyam produced in Uganda is substantially different from that produced in Kenya, regardless of the variety. Information  obtained from this study can be used to develop cocoyam based food products with enhanced nutrition and potential to promote commercial scale production and utilization of cocoyam in East African countries. 
 
   
 
 Key words: Colocasia esculenta, Xanthosoma sagittifolium, proximate composition, mineral content, Lake Victoria basin.