Physicochemical, rheological and functional properties of modified starches from the tubers of Plectranthus esculentus Pleactranthus esculentus starch

Abstract

power and solubility were determined by gravimetric techniques at 10% w /v of starch dispersion. Rheological properties were determined on a Bohlin Gemini HR Nano Rotonetic drive 2 rheometer while the structural properties were evaluated using Fourier transform infra-red (FTIR) spectroscopy and x-ray diffractometry (XRD). FTIR confirmed the presence of acetyl groups at 1700 cm -1 and carboxymethyl groups at 1579 cm -1 . The acetylated derivatives were resistant to syneresis. XRD displayed a crystallized region with three prominent peaks, centred on 2θ = 15.1, 17.2 and 23.2°, for the native starch, acetylated and oxidized starches while the carboxymethylated, xerogelized, and acetylated/xerogelized derivatives were typically amorphous. The derivatives (carboxymethylated and acetylated/xerogelyzed) were thermally stable and formed viscoelastic gel at room temperature. Conversely, dispersions of the native starch and the derivatives (acetylated, oxidized and acetylated/oxidized) exhibited thermal transitions due to gelatinization. The acetylated derivatives have potential in terms of shelf-life, stability, and diverse opportunities for multiple applications in pharmaceutical and food industries.