LAUSR

BACKGROUND Acetylated based starches are broadly used in the food industry as emulsifiers, thickening and film forming agents. Better understanding of the structural and rheological parameters would facilitate the selection of optimal acetylated starches for a particular application. Analytical techniques such as nuclear magnetic resonance (1 H-NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) patterns, and rheological properties viz; elastic (G'), loss (G") moduli, complex viscosity (η*) and study shear stress (δ) were determined for acetylated fox nut starch (FNS) samples. RESULTS The degree of substitution (DS) significantly varied with increasing acetyl concentration from 2-6%. 1 H-NMR of acetylated FNS showed an additional chemical shift at 2.08 ppm, than native FNS confirming the linking of H or -OCH3 group. The acetylated FNS starches showed a better short range ordering of molecules as confirmed by FTIR. A significant increase in the functional and gelatinization properties with increasing acetyl concentration was observed. The power law parameters (n, K) and dynamic moduli (G' and G") increased with increase in acetyl concentration and presented shear thinning behavior. The gelatinization peak temperature and enthalpy decreased with increasing acetyl concentration. CONCLUSION The observed DS below 2.5 and the significant alteration of functional and structural properties with varying acetyl content would mean safe food consumption and extended use of FNS in food and allied industries. This article is protected by copyright. All rights reserved.