Influence of the Carboxylic Function on the Degradation of d-Galacturonic Acid and Its Polymers

Abstract

Past investigations have shown high browning potential during the caramelization of sugar acids in comparison to reducing sugars. However, no approaches to elucidate the chemical mechanisms have been made. Therefore, this study aims to clarify the reasons for the high browning potential by measuring the mutarotation velocity and the elimination of CO2 during the heat treatment of uronic acids. Performed polarimetric experiments show that the mutarotation velocity of d-galacturonic acid exceeds that of d-galactose by a factor of nearly 4.5. However, the ring opening velocity is not the only parameter that differs between the two carbohydrate structures. Measurements of the release of CO2 of heated d-galacturonic acid at 60 °C show a steady increase, and after 48 h, 6% of degraded d-galacturonic acid has eliminated CO2. CO2 release was also found during the heating of pectin, indicating a decarboxylation reaction during thermal degradation. One of the degradation reactions postulated for the release of CO2 leads to α-ketoglutaraldehyde, which is responsible for the formation of several chromophoric substances.

pH‐responsive gum tragacanth hydrogels for high methylene blue adsorption

“…[39][40][41] Recently, pectin degradation studies revealed a complex process that includes demethoxylation, depolymerization by backbone hydrolysis, and cleavage of neutral sugar side chains. 42,43 Such processes require water molecules and, therefore, are affected by moisture content. Other depolymerization processes observed in pectins were ⊎-elimination and decarboxylation, neither of which require water.…”

“…Recently, pectin degradation studies revealed a complex process that includes demethoxylation, depolymerization by backbone hydrolysis, and cleavage of neutral sugar side chains 42,43 . Such processes require water molecules and, therefore, are affected by moisture content.…”

Efficient Production of 2,5-Diketo-D-gluconic Acid by Reducing Browning Levels During Gluconobacter oxydans ATCC 9937 Fermentation

“…Many substances will be browning during storage (Tan et al, 2020;Fatouros et al, 2021). Browning mainly includes enzymatic and non-enzymatic two pathways (Paravisini and Peterson, 2019;Pham et al, 2020).…”