LOW‐METHOXYL PECTIN PREPARED BY PECTINESTERASE FROM Aspergillus japonicus

ABSTRACT Pectinesterase was purified from the culture medium of Aspergillus japonicus completely free from pectin depolymerizing enzymes. The purified enzyme was able to convert high‐methoxyl pectin into low‐methoxyl 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 low‐methoxyl pectin.