STUDY ON THE MODIFICATION OF GREEN BANANA STARCH BY CARBOXYMETHYLATION METHOD

Abstract

The content of NaOH influences the substitution of carboxymethyl groups in the polysaccharide chain and the digestibility of banana starch. The carboxymethylation process exhibits a high degree of substitution (DS) ranging from 0.31 to 0.63 and the resistant starch (RS) content increases from 29.84% to 41.67% as the sodium hydroxide concentration rises from 5% to 10%. At a NaOH concentration of 12%, the granular structure is disrupted and the crystallinity significantly decreased (from 25.18% to 3.72%), lead to a reduction in both DS and RS content (0.52 and 35.28%, respectively). Therefore, banana starch treated with 10% NaOH relative to starch weight is considered optimal. At this concentration, the functional properties of the starch reached their highest values, such as swelling capacity (35.14 g/g at 90°C), water solubility (32.01% at 90°C), freeze-thaw stability (19.71% after four freeze-thaw cycles) and oil and water absorption capacities (OAC 1.78 mL/g and WAC 1.95 mL/g).