A comparative study of functional and structural properties of starch extracted from Dioscorea rotundata and Colocasiaesculenta

Abstract

This study was designed to compare some functional and structural properties of yam (Dioscorea rotundata) and cocoyam (Colocasia esculenta) starches. The yield, swelling power, amylose content, paste clarity, and viscosity of yam and cocoyam starches were determined. Likewise, the structural conformation of the starches was evaluated using optical and scanning electron microscopy as well as FTIR spectroscopy. The result showed that, the yield, swelling power, amylose content, and paste clarity of yam and cocoyam starches were 33.38% (217 ± 0.88 g) and 25% (108.75 ± 0.88 g); 38.4 ± 0.2 g/g and 33.4 ± 0.1 g/g; 25.96 ± 0.16 and 22.99 ± 0.04 and 44 ± 2% 34 ± 1% and 350 ± 15.28 and 210 ± 10 mPa.s, respectively. The yield, swelling power, amylose content, paste clarity, and viscosity of yam starch were significantly higher (p < 0.05) than from cocoyam starch. The result of FTIR spectroscopy of yam and cocoyam starches at OH stretch was 3176.45 and 3251.60 cm−1, respectively. At OH stretch cocoyam starch gives higher absorption intensity and broader shape than yam starch, which could be attributed to higher crystallinity of cocoyam starch granules compared to yam starch. The optical and scanning electron microscopy indicated that the granular shape of yam starch was oval whereas cocoyam starch was polygonal with fissures and cavities. In conclusion, from the various functional and structural properties of yam and cocoyam starches evaluated, both could be a cheap and good sources starch, which could be worked for industrial application.