Thermal Crosslinking of Maltodextrin and Citric Acid. Methodology to Control the Polycondensation Reaction under Processing Conditions
This paper presents an affordable methodology for the analysis of the crosslinking, by polycondensation reaction, between maltodextrin and citric acid under thermal processing. This methodology is based on three complementary analytical techniques: Fourier Transform Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and rheometry. FTIR has been found to be a powerful technique for the characterization of both the esterification reaction and other non-covalent interactions between maltodextrin and citric acid. TGA has been mainly applied to quantify the progress of the polycondensation reaction. Rheometry has been extensively used to understand the crosslink formation resulting from the polycondensation process between maltodextrin and citric acid, allowing the determination of the gel time. Furthermore, these techniques have revealed added value when used as complementary techniques. For instance, the FTIR results supported the conclusions from the study of polycondensation reaction progress by TGA. Similarly, the TGA results about the polycondensation reaction temperature are consistent with the rheology study. Overall, the insightfulness and accuracy of the methodology presented in this paper make it very useful as a tool to optimize industrial processing of materials which apply binding systems based on maltodextrin and citric acid.