Extraction and characterization of the pectic substances from Japanese pepper (Zanthoxylum piperitum DC.) fruit

Abstract

Pectic substances were extracted from Japanese pepper (Zanthoxylum piperitum DC) fruit with hot diluted HCl (90C, pH 2.2). The yield of the pectic substances was 8.4% (w/w) based on dry material. The contents of total carbohydrate, anhydrogalacturonic acid, ash, protein, and moisture of the pectic substances were 84.1, 66.9, 3.6, 2.7, and 9.6% (w/w), respectively. The degree of methylation was estimated to be 80.3% by using alcohol oxidase test. This indicated that the pectic substances are high methoxyl pectins and have an ability to form sugar gels. The jelly grade of the pectic substances was estimated to be 130 (USA-SAG) at standard condition. Viscosity-average molecular weight was relatively low (30.3 kDa). When the molecular weight distribution was checked by gel-permeation chromatography on Sepharose CL-4B, the elution profile of the pectic substances was highly polydispersed extending from 40 kDa (or less) to 2000 kDa.