LOW‐METHOXYL PECTIN PREPARED BY PECTINESTERASE FROM Aspergillus japonicus

Abstract

Pectinesterase was purified from the culture medium of Aspergilhs juponicus completely free from pectin depolymerizing enzymes. The purified enzyme was able to convert high-methoxyl pectin into lowmethoxyl pectin capable of forming strong gels with calcium ion. The maximum gel strength of enzyme-demethylated pectin was obtained at methoxyl content of 6.3%, calcium concentration of 41.8 mg/g of pectin and pH 3.5. The low-methoxyl pectin, however, formed weaker gels at low concentrations of calcium ion and low pH. DEAE-cellulose column chromatography indicated that the enzyme-demethylated pectin was homogeneous with respect to methoxyl groups of the molecules. It was suggested that this homogeneity may be probably responsible for high gel strength of the lowmethoxyl pectin.

Pectin from Passion Fruit Fiber and Its Modification by Pectinmethylesterase

“…The charge density was also very homogeneous. This is in agreement with the mechanism generally accepted for Aspergillus species PMEs (26,59). The modification of the pectin by PME was also confirmed by its higher susceptibility to chain cleavage by endo-PG (data no shown).…”

“…No syneresis was observed in the gels prepared by the enzymatic procedure. This might be related to the random mode of demethylation by fungal PME (25,26). For production of jams and similar types of products, pectin is usually added as a gelling agent.…”

“…With the random mechanism, low-ester pectins are produced that have relatively reduced calcium sensitivity. PMEs free from depolymerases are of special interest for preparing low methoxyl pectins (26), french cider (27), vegetable infusion (28) and development of "in situ" gelation in the jam industry (29).…”

Hairy plant polysaccharides: a close shave with microbial esterases

“…In many cases, the synergy is of a reciprocal nature, where the action of either enzyme enhances the action of the other. Some pectin methylesterases, such as those from Aspergillus spp., act by a multi-chain mechanism removing methoxy groups at random (Ishii et al, 1979), in contrast to plant pectin methylesterases (e.g. isolated from tomato or orange peels), which act preferentially either at the non-reducing end or next to a free carbonyl group and proceed along the molecule by a single-chain mechanism (Kohn et al, 1983).…”

Release of Methanol and Depolymerization of Highly Methyl Esterified Apple Pectin with an Endopolygalacturonase fromAspergillus nigerand Pectin Methylesterases fromA. nigeror from Orange

“…In the second process, PME frees methanol, an undesirable compound in the nonconcentrated juice, and could influence the action of polygalacturonases on the galacturonan chain and on the clarification of the final juice (2). In the current work we studied methanol release from highly methyl esterified apple pectin with two PME: (a) a PME from Aspergillus niger which acts by a multichain mechanism removing the methoxyl group at random (3,4), and (b) a PME from orange which acts either at the nonreducing end or next to a free carboxyl group and proceeds along the molecule by a single chain mechanism (5)(6)(7)(8).…”