Correlation between Kinetics of Pectin Degradation and Texture Loss of Okra (<i>Abelmoschus esculentus</i> L.) Puree during Thermal Treatments

Abstract

Okra is a common vegetable in the African cuisine, known for its distinctive slimy texture. Plant cell walls include hydrocolloids, especially pectin, which contribute to their sliminess. This textural property is known to become lost during thermal treatment. In this research, okra hydrocolloid is extracted and used to produce a model medium at a pH of 6.0, representing okra’s natural state. This medium is subjected to various controlled thermal treatments (70–130 °C) to evaluate their impact on pectin degradation. At the same time, the texture of okra puree is also assessed using an instrumental method under the same conditions. The two main products of pectin degradation—reducing end sugars from depolymerization and methanol from a demethylation—are measured and found to show an increase as a function of time and temperature. Kinetic modeling indicates that a first-order reaction fits well with the experimental concentrations of both products. The rate constants, as a function of temperature, aligns with the Arrhenius model, confirming the chemical basis of the degradation. Instrumental results correlate well with the production of methanol and reducing end sugars, indicating that pectin degradation is the primary cause of texture changes during the thermal treatment of okra and that this change can be controlled by adjusting the temperature.

Keywords

• okra
• hydrocolloid
• mucilage
• pectin degradation
• hydrolysis
• demethylation