An Assessment of Pectin Thiolation parameters: Degree of Esterification, Conjugate and Cross-linking Reagent Concentrations

Abstract

This study focuses on the optimisation of pectin thiolation using L-cysteine and assesses the impact of the degree of esterification (DE), polymer to L-cysteine ratio, and concentrations of conjugating reagents on the total and free thiol content of both highly esterified (HE) (>50% esterified) and lowly esterified (LE) (<50%esterified) pectin thiomers. The thiolation process was analysed under variations of four factors - the type of pectin used (HE and LE), the polymer to cysteine ratio, and concentrations of the conjugating reagents 1-(3-dimethylaminopropyl)-3-ethylcarbodiimidehydrochloride (EDAC) and N-hydroxysuccinamide (NHS) (0 mM, 25 mM, 50 mM &100 mM). Thiol content was determined using Ellman’s reagent, with spectrophotometric methods. Statistical analysis via multivariant analysis of variation(MANOVA) indicates a significant relationship with respect to total thiol content considering DE, polymer to cysteine ratio, and EDAC concentration(P<0.05). Concordantly, MANOVA indicated a significant relationship with respect to free thiol content considering DE, polymer to cysteine ratio, and both EDAC and NHS concentrations (P<0.05). Increasing EDAC concentration corresponded with increased total and free thiol content in both types of pectin. In contrast, elevating NHS concentration led to reduced total thiol content across most ratios. Thus, the study delineates critical parameters in the thiolation of pectin using L-cysteine.

Keywords

• pectin
• degree of esterification
• thiomer
• l-cysteine