Comparative analysis of starch granule morphology and amylose-amylopectin ratios in cassava flours from genotypes with varying postharvest deterioration tolerance
Year: 2025
Type: article
Abstract: Advances in cassava breeding have produced genotypes with substantially delayed postharvest physiological deterioration (PPD), yet the structural basis of starch in these improved materials — particularly granule morphology, amylose-to-amylopectin ratio, and crystallinity — remains poorly characterised in comparative analyses involving contrasting PPD tolerance. This research compared the starch granule morphology, amylose content, amylopectin distribution, and X-ray diffraction patterns of five low-PPD and five high-PPD cassava genotypes cultivated in Ethiopia. Granule morphology was characterised by scanning electron microscopy (SEM) and image analysis for size distribution. Amylose content was quantified by the iodine colorimetric method, and amylopectin branch chain length was profiled by fluorophore-assisted carbohydrate electrophoresis following debranching with isoamylase. Starch crystallinity type and degree were determined by X-ray powder diffraction. The relationship between these structural parameters and cookie textural properties — hardness, fracturability, and spread ratio — was established by Pearson correlation analysis. Results demonstrated that low-PPD genotypes produced significantly larger starch granules (mean diameter 13.6-16.4 μm versus 10.4-12.1 μm) with lower amylose content (17.8-20.1% versus 21.8-24.2%) and reduced starch crystallinity (37.4-41.3% versus 41.2-44.7%). All ten genotypes exhibited type-A X-ray diffraction patterns characteristic of cereal and root starches. Granule diameter was significantly and negatively correlated with cookie hardness (r = −0.81, p < 0.01) and fracturability (r = −0.74, p < 0.01), while positively correlated with spread ratio (r = 0.76, p < 0.01). These findings reveal that the structural differences between low-PPD and high-PPD cassava starches have functional consequences for cookie texture, and that starch granule morphology may serve as a selection criterion in breeding programmes targeting confectionery-grade cassava flour.
Language: English
Subfield: Nutrition and Dietetics
Field: Nursing
Domain: Health Sciences
SDG: Zero hunger
Open Access status: bronze
OpenAlex ID: W7170934654