Influence of 2-octenyl-1-succinic anhydride (OSA) concentration on the functional, rheological, structural and flow properties of starch from Indian Teff (Eragrostis tef).

Abstract

Teff (Eragrostis tef) starch was esterified using 2-octenyl-1-succinic anhydride (OSA) (1 to 3 %), resulting in degrees of substitution (DS) 0.007-0.020. The functional, flowability, pasting, rheological, thermal, and structural properties of the modified starches were investigated. The amorphous regions of the starch granules were more reactive to the modification than the crystalline regions, potentially affecting the strength of the amorphous regions while leaving the crystalline structure intact. The primary factor influencing the pasting and thermal properties of the OSA-modified starches was the amylose content, which decreased significantly upon esterification. OSA modification increased the water solubility and swelling power of the starch. Rheological tests indicated that with increasing DS, the pasting temperature reduced from 77.59 °C to 76.81 °C, while the pasting viscosity increased. Thermograms showed lower onset, peak, end temperatures, and enthalpy of gelatinization in OSA-modified starches compared to their native counterparts. No significant changes were observed in the X-ray diffractograms, verifying the absence of reaction in the crystalline region. The results of FTIR and NMR confirmed the successful reaction between OSA and starch by formation of new peaks. These findings demonstrate that OSA-modified starches possess distinct properties that can meet various requirements in the development of new products.