Comparing properties of starch and flour of yellow-flesh cassava cultivars and effects of modifications on properties of their starch

Abstract

The flour, native starch and modified starches produced from three pro-vitamin A cassava cultivars were studied for their properties. Loose (0.51–0.54 g/mL) and packed (0.58–0.71 g/mL) bulk densities of cassava flours were significantly lower than that for starches, which were 0.53–0.79 g/mL and 0.67–1.01 g/mL, respectively. Modifications by annealing, heat-moisture treatment (HMT), and citric acid crosslinking generally increased porosity. The starch granules were predominantly small-sized (1–10 µm), round shaped and had normal distribution of granule diameter. Citric acid crosslinking caused scathing of starch granules and significantly reduced lightness (L*) and whiteness (% W) of the starches. The flours had higher crude protein and ash, but lower nitrogen free extract and apparent amylose than starches. Water absorption capacity (WAC), alkaline water retention (AWR) and swelling power were significantly reduced by annealing, but significantly increased by HMT and citric acid cross-linking. The modifications variably influenced oil absorption capacity (OAC) depending on cultivar. The cassava flours and native starches formed gels at low concentration (2%), but annealing, HMT, and citric acid crosslinking of starch increased the concentration required to initiate gel formation to 2–6%, 6–8%, and 10–20%, respectively. Paste clarity (% T) was significantly lower for flours (5.4–27.6%) than starches (2.3–57.5%) and was reduced by the modifications. Pasting properties differed significantly with modifications and cultivars. All modifications significantly reduced breakdown and setback viscosity. Citric acid crosslinking specifically reduced pasting temperature, and reinforced starch endurance to shear.