Resistant starch formation in unripe plantain flour under two different drying conditions

Unripe plantain is a potential commodity for producing flour with low digestibility due to its dietary fiber and resistant starch content, thus more beneficial for health such as for blood glucose control and blood lipid profile improvement. The present study aimed to characterize the physicochemical and resistant starch content of unripe plantain flour produced under two different drying conditions namely: one-step drying and two-step drying technique. The unripe plantain flour control (unmodified) was produced by drying under one temperature for a fixed duration (60°C for 6 hours), whereas the modified one was produced using a two-step drying process: first, at 40°C for 5 hours, followed by 80°C for 4 hours. The flour was characterized for its resistant starch content, proximate composition, colour and pasting properties. The results showed that modified unripe plantain flour contained higher resistant starch (6.98 ± 0.21%) as compared to the control one (5.21 ± 0.49%, p<0.05). Whereas starch content was 60.14 ± 0.19% and 55.76 ± 0.18% for the modified and the control flour respectively. The two-step drying condition also increased the pasting temperature of the modified unripe plantain flour by nearly 2°C (84.37°C) compared to the control flour (82.65°C). Thus, two-step drying condition increased the resistant starch content and altered the pasting properties of unripe plantain flour.