Effect of growth period on the multi-scale structure and physicochemical properties of cassava starch.

Starches were isolated from South China 5 (SC5) cassava harvested for 7, 8, 9, 10 and 11 months. During growth, the granule size, lamellar structure, crystalline structure and digestibility changed slightly, while the amylose content varied between 20.93% and 22.61%. However, the molecular weight showed an obvious increase as the harvesting time increased to 9 months, and then decreased during 9-11 months. The pasting behaviors were greatly affected by harvesting time. A shorter growth time led to higher pasting temperature, and lower peak, breakdown and setback viscosities. This trend became contrary when the growth time prolonged from 9 to 11 months. Hence, the starch harvested at 9 months showed the lowest pasting temperature (64.6°C), but highest paste viscosity (2105cP) and retrogradation tendency. All these results confirm that the growth time of 9 months was the turning point for the physicochemical features of SC5 during growth. This study provides fundamental data for rationally tailoring cassava starch properties by simply controlling the harvest time.