A green/sustainable organocatalytic pathway for the preparation of esterified supercriticalCO2‐dried potato starch products

Abstract

AbstractProduction of renewable and modified starch‐based products was achieved using a sustainable catalyst and an environmentally friendly drying process via supercritical CO2. Potato starch was modified via a sustainable and green esterification process with acetic anhydride reagent implementing a novel organocatalytic pathway at different periods of time (0.5, 3 and 7 h) by applying an esterification reaction at 120°C targeting intermediate degrees of substitution (i.e., 0.2 < DS <1.5) finding potential applications as polymer packaging materials. The final modified samples were divided into two fractions, where the first fraction was dried under vacuum at 80° C for 24 h and the second fraction was dried under supercritical CO2at 40° C and 100 bars for 2 h. The final products were analyzed using an array of characterization techniques such as Fourier transform infrared (FTIR), Proton nuclear magnetic resonance (1H‐NMR), scanning electron microscopy (SEM), X‐ray diffraction (XRD), N2physisorption, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Karl Fischer. The chemical structure of both fractions was similar as confirmed by the different characterization techniques. Drying under supercritical CO2preserved some pores in the modified starch materials as opposed to thermal oven drying, as was confirmed by N2physisorption measurements. The degree of substitution (DS) was determined using three different techniques; titration, high performance liquid chromatography (HPLC) and solution state proton nuclear magnetic resonance (1H NMR) spectroscopy and the values were greater than 0.2 and less than 1.5 indicating intermediate degrees of substitution.