Abstract:
Starch availability has been implicated in unripe
matured banana (Musa species), which when processed
yields flour suitable for application in low gluten and
composite wheat formulations. Unripe Musa species:
Williams, Luvhele, Mabonde and Muomva-red obtained
from fruit bunch were pretreated with ascorbic, citric and
lactic acids, processed into 50 g of flour and characterised
for their functional and thermal properties. Scanning
electron microscope of unripe banana flour (UBF) showed
varying micrographs of flour, with polygonal for Luvhele,
oval for Mabonde, elongated for Muomva-red and between
polygonal and spherical for Williams. The bulk density of
UBF samples was within the range of 0.66–0.84 g/mL for
all organic acid pretreatment while citric acid pretreated
UBF had the least browning index. Significant difference
(p\0.05) was recorded in swelling power with no significant
difference in water solubility index except for
Mabonde UBF. Thermal properties showed single
endothermic transition for all UBF samples at various
pretreatment concentration. The onset temperature (To) of
UBF ranges from 49.82 to 65.59 C, peak temperature (Tp)
from 60.11 to 76.71 C, conclusion temperature (Tc) from
70.36 to 94.16 C and enthalpy of gelatinization (DH) from
2.61 to 32.24 J/g. Short amylopectin chains present in
starch of UBF was attributed to low To, Tp, Tc and
DH values recorded for Mabonde cultivar, while the contribution
of heat-moisture treatment rather than organic
acid pretreatment of UBF samples was attributed to different
gelatinization and transition temperatures recorded
for all cultivars examined.
