De-esterification Of Pectin Research Articles

Ca2+ in Cell Walls of Ripening Tomato and Peach

Abstract Ca2+ content in cell wall-middle lamella (CW–ML) areas of outer and inner pericarp, placenta, and gel parenchyma of ripening tomato (Lycopersicon esculentum Mill. cvs. Celebrity and Jumbo) and mesocarp of ripening peach [Prunus persica (L.) Batsch cv. Georgia Belle] was determined by energy dispersive (EDS) X-ray microanalysis. Ca2+ increased from 1.50 to 6.95 mg·g–1 dry weight in CW–ML of outer pericarp and 0.98 to 2.60 mg·g–1 dry weight in CW–ML of inner pericarp during ripening. Ca2+ content remained constant in tomato placenta and peach mesocarp, and was undetectable in tomato gel parenchyma throughout ripening. CW–ML of peach mesocarp had lower Ca2+ content than tomato pericarp and placenta at all ripening stages, but total peach uronic acid content was 2.5 times greater. Pectin methylesterase (PME) activity increased in tomato pericarp as fruit ripened, but remained low and unchanged in placenta and gel parenchyma. PME treatment of pericarp increased amounts of CW–ML Ca2+ in the breaker stage but not in the green mature stage. The results indicate that increased amounts of Ca2+ are bound to CW–ML of tomato pericarp as ripening occurs but not in placenta or peach mesocarp. Pectin deesterification and wall softening during ripening may in part be factors that control the presence and amount of CW–ML Ca2+.

Limit to the deesterification of citrus pectin by citrus pectinesterase.

Limit to the deesterification of citrus pectin by citrus pectinesterase.

The distribution of free and esterified carboxyl groups within the pectin molecule after the action of pectin esterase from Aspergillus niger and oranges

By reaction of pectin esterase (PE) from Aspergillus niger and oranges as well as lye, with 95% esterified citrus and apple pectin we prepared series of preparations with degrees of esterification between 35 and 77%. In these partial deesterified pectins the form of distribution of the free and esterified carboxyl groups has been determined from the activity coefficient gamma Ca2+ of the calcium counterions in the solutions of the corresponding calcium pectinates, from the electrostatic free enthalpy delta (Gel/N)KCa of the ion exchange Ca2+----2K+ in these systems as well as from the relative activity of the polygalacturonase reacting with sodium pectinate. The PE from A niger hydrolyzes the esterified carboxyl groups more or less randomly, in a manner similar to the effect of lye on pectin. On the other hand PE from oranges brings about block-like groupings of free carboxyl groups in the pectin molecule. The study revealed different reaction mechanisms of the pectin deesterification by pectin esterases from Aspergillus species and higher plants.

Mode of pectin deesterification byTrichoderma reesei pectinesterase

Trichoderma reesei pectinesterase (isoelectric point 8.3–9.5; pH-optimum 7.6) catalyzes deesterification of pectin by giving rise to blocks of free carboxyl groups in the macromolecule; a mode similar to that observed with higher plant pectinesterases which also have Ip and pH-optima in the alkaline region.

Deesterification mode of pectin by pectin esterases of Aspergillus foetidus, tomatoes and alfalfa

The effect of microbial pectin esterases (Aspergillus foetidus) and higher plants (tomatoes, alfalfa) on high-esterified pectin was investigated. Pectin derivatives of esterification degree E 42-66% were prepared by a partial deesterification catalyzed by the above-mentioned enzymes. The distribution pattern of free and esterified carboxyl groups in the linear pectin macromolecule was determined on the basis of activity coefficients of counterions γCa2+ as found in solutions of the proper calcium pectinates. The activity coefficients γCa2+ were compared with the corresponding γCa2+ values determined in pectins partially deesterified with alkali, with a random distribution pattern of free carboxyl groups. The plant pectin esterases under investigation lead to a block-wise arrangement of the free carboxyl groups in the pectin molecule, whereas A. foetidus pectin esterase cleaves randomly the ester groups in the same mode as do the alkali hydroxides. Significant differences were observed with final products of enzyme deesterification of pectin even in the selectivity of Ca2+ 2K+ cation exchange, as documented by the change of electrostatic free enthalpy of exchange of these cations. The different mechanism of action of plant and A. foetidus pectin esterases was thus unambiguously proved by a physico-chemical method.

The effect of processing on the texture of canned mung bean (Phaseolus aureus) shoots

AbstractThe effect of various processing regimes on the pectic substances and the final texture of canned mung bean shoots has been studied. A blanching temperature of 75°C for 30 s was optimal in activating the native pectinesterase of the shoots and a holding temperature of 55°C for an optimal 30 min led to maximal deesterification of pectin. This treatment resulted in a canned product that was superior to a sample blanched at 100°C.; the addition of calcium ions did not improve the product.

Chilling-injury in cucumbers. V. Polysaccharide changes in cell walls

A decline in the hot-water-soluble pectin and an increase in the hot-water-insoluble pectin were observed when cucumber fruits were subjected to chilling temperatures. Infrared absorption spectra revealed the presence of highly esterified carboxyl groups in the soluble pectin, and of free carboxyl groups in the insoluble pectin. An increase of the insoluble pectin during chilling was also found in other chilling-sensitive plants. From these results it is suggested that a de-esterification of pectin and the concomitant increase of polymeric pectin takes place during chilling, making cell walls firmer, and that these pectic changes may be a characteristic common to a number of chilling-sensitive plants.

Acceleration by Electrolytes of Alkaline De-esterification of Pectin

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAcceleration by Electrolytes of Alkaline De-esterification of PectinHans LineweaverCite this: J. Am. Chem. Soc. 1945, 67, 8, 1292–1293Publication Date (Print):August 1, 1945Publication History Published online1 May 2002Published inissue 1 August 1945https://doi.org/10.1021/ja01224a023RIGHTS & PERMISSIONSArticle Views84Altmetric-Citations12LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (254 KB) Get e-Alerts Get e-Alerts