Accumulation dynamics and physicochemical variability of starch in cultivars of Canna edulis Ker

Abstract

Canna edulis, also known as achira or sagu, is widely grown in South America because its rhizomes are a major source of starch for food and agroindustry. This study aimed to assess the accumulation rate and physicochemical changes of starch from four canna cultivars (Verde, Nativa, Maituna and Morada), grown under a traditional system, in the southwest region of Colombia. The rhizomes were harvested after planting (between five and nine months) to extract and characterize the starch. It was found that the starch yield (% wb) was related to the plant development age, reaching a maximum at eight months for all cultivars (12.78 ± 0.19 % - Verde; 12.46 ± 0.18 % - Maituna; 12.17 ± 0.19 % - Nativa; 11.10 ± 0.18 % - Morada). The average chemical composition (% wb) of the native starch throughout the rhizome development, for all cultivars, was: 86.68 % of starch, 1.12 % of protein, 0.43 % of dietary fiber, 0.14 % of ash and 11.57 % of moisture. At the optimum harvest age, the minimum and maximum amylose contents were 45.63 % (Maituna) and 54.47 % (Verde). The starch granule size among the cultivars showed a normal distribution, with a range of 40 ?m to 80 ?m and mean of 59.9 ?m. The pasting curves per cultivar showed that the starch generated very high viscosity gels, unstable to the heating-cooling cycles, and high retrogradation.

KEYWORDS: Rhizome, agroindustry, flour.