Talipot palm (Corypha umbraculifera L.) a nonconventional source of starch: Effect of citric acid on structural, rheological, thermal properties and in vitro digestibility

Starch from talipot palm trunk (Corypha umbraculifera L.), a new starch source, was treated with different citric acid concentrations (5%, 10%, 20%, and 40% of the dry weight of starch) to produce citrate starch. The influence of citric acid treatment on physicochemical, pasting, structural, thermal, rheological, and digestibility properties of talipot palm starch were studied. A new peak at 1728 cm(-1) was observed in the Fourier-transform infrared spectroscopy (FTIR) spectra of citric acid-treated starches, which confirmed the formation of an ester bond between starch molecule and citric acid. The crystalline pattern of talipot palm starch was unaffected by citric acid treatment, whereas the relative crystallinity decreased from 16.35% to 3.06%. The Rapid Visco Analysis of starch treated with citric acid did not show any characteristic peaks, however, the untreated starch showed a peak viscosity of 3646 cP. The gelatinization parameters decreased with an increase in the degree of substitution, and the enthalpy of gelatinization (Delta Hgel) decreased from 11.19 J/g to 6.37 J/g. The in-vitro digestibility of talipot palm starch was decreased by citric acid treatment, and that of the slowly digestible starch (SDS) and resistant starches (RS) increased significantly (p <= 0.05) from 31.71% to 39.43% and 37.55% to 53.38%, respectively. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study found that citric acid treatment can improve the crystallinity and gelatinization properties of talipot palm starch, reduce its enthalpy, and increase the content of slowly digestible and resistant starches.