Textural Properties of Gelling System of Low‐Methoxy Pectins Produced by Demethoxylating Reaction of Pectin Methyl Esterase

Abstract

After deesterification of commercial pectins with a pectin methyl esterase (PME), their gelling properties were characterized using instrumental texture analysis. The final degree of esterification (DE) of the high- and low-methoxy pectins reached approximately 6% after the PME treatment, while deesterification of low-methoxy amidated pectin stopped at 18% DE. Furthermore, DE of high-methoxy pectin was tailored to be 40%, which is equivalent to the DE of commercial low-methoxy pectin. As a result, significant changes in molecular weight (Mw) distribution were observed in the PME-treated pectins. The texture profile analysis showed that PME modification drastically increased hardness, gumminess, and chewiness, while decreasing cohesiveness and adhesiveness of the pectin gels (P < 0.05). The pectin gel with relatively high peak molecular weight (Mp, 3.5 x 10(5)) and low DE (6), which was produced from high-methoxy pectin, exhibited the greatest hardness, gumminess, chewiness, and resilience. The hardness of low-methoxy amidated pectin increased over 300% after PME deesterification, suggesting that the effects of amide substitution could be reinforced when DE is even lower. The partial least square regression analysis indicated that the Mw and DE of the pectin molecule are the most crucial factors for hardness, chewiness, gumminess, and resilience of gel matrix.

Environmentally friendly preparation of pectins from agricultural byproducts and their structural/rheological characterization

“…It would be why pectins obtained by physical/enzymatic treatments exhibited lower viscosity than chemically-extracted pectins at the same concentrations. These results were in good agreement with previous studies that reported a decrease in the hardness of pectins gels with increasing degree of esterification (Kim et al, 2008). In addition, since viscosity is a function of molecular weight, the viscosity variations between two pectin samples could be partly attributed to their molecular weights.…”

Molecular differences of low methoxy pectins induced by pectin methyl esterase I: Effects on texture, release and perception of aroma in gel systems

“…They showed greatly increased sensory firmness, springiness, coarseness of mass, and chewiness, but reduced sensory adhesiveness, cohesiveness, and mouthcoating. In our previous study, the textural properties of PME-treated pectin gels based on the results of instrumental texture profile analysis were reported (Kim et al, 2008). The sensory test results from this study verified previous texture profile analysis results.…”

“…The treated pectins were designed to have different molecular weights, degrees of esterification, and degrees of amidation (DA). Detailed descriptions of the PME-de-esterification and the molecular properties have been reported in our previous study (Kim, Yoo, Kim, Park, & Yoo, 2008). The molecular properties of the pectins are given in Table 1.…”

“…a All values were measured in an earlier study by the authorsKim et al (2008). b Degree of methylesterification.…”

Pectin extraction from cv. Pink Lady (Malus pumila) apples

“…According to the analyses conducted in this study, the pectin extracted from apples would be within the range of HM pectins because, in most of the treatments, a degree of esterification higher than 50% was obtained, indicating that the pectin is suitable for use in the manufacture of jams, jellies and preserves due to its gelling property (Kim et al, 2008). A greater amount of pectin was obtained at a lower pH, but this treatment also produced a lower quality pectin due to its low degree of esterification.…”