Physicochemical, morphological, thermal and rheological properties of starches separated from kernels of some Indian mango cultivars ( Mangifera indica L.)

Abstract

The starches separated from kernels of five different Indian mango cultivars (Chausa, Totapuri, Kuppi, Langra and Dashehari) were investigated for physicochemical, morphological, thermal and rheological properties. Mean granule length and width of the starches separated from mango cultivars ranged between 15.8–21.7 and 8.7–14.1 μm, respectively. The shape of starch granules varied from oval to elliptical. Amylose content of mango kernel starches from different cultivars ranged from 9.1 to 16.3%. Totapuri kernel starch, with the largest mean granular size, had the highest amylose content, while Chausa kernel starch, with the lowest mean granular size had the lowest amylose content. The transition temperatures ( T o, T p and T c) and enthalpy of gelatinization (Δ H gel) were determined using differential scanning calorimetry (DSC). T o, T p and T c varied from 73.4 to 76.3, 78.1 to 80.3 and 83.0 to 85.7 °C, respectively. Chausa kernel starch showed the highest T o, T p, T c, Δ H gel and peak height index among starches from different mango cultivars. The rheological properties of the starches from different mango cultivars measured using a dynamic rheometer, showed significant variations in the peak G′, G″ and peak tan δ values. Totapuri kernel starch showed the highest peak G′, G″, breakdown in G′ and lowest peak tan δ values. The large-size granules of Totapuri kernel starch appeared to be associated with higher values of peak G′ and G″. The turbidity of the gelatinized aqueous starch suspensions, from all mango cultivars, increased with increase in storage period. Dashehari starch paste showed lower turbidity values than other mango cultivars.