Pectins, - with low methoxyl contents prod from citrus peel and used - in breakage-resistant weeping free gels

摘要

Pectins, able to produce gels in the presence of Ca ions which are resistant to breakage and separation, are prepared by (1) extracting a citrus peel such as lemon peel at 70 - 80 degrees C in an aq. acid soln. at pH 2.3 - 2.8 e.g. using sulphurous acid, to extract a pectin having a mol. wt. of 180,000 - 220,000, (2) ppting the pectin from soln. e.g. using aluminium chloride, (3) treating the ppted pectin at 15 - 30 degrees C with an alcohol/acid soln. e.g. isopropanol/HCl, conc. being 0.7 N-1.5 N, to reduce the methoxy content to 7.0 - 8.5% and (4) filtering and recovering the pectin product. - The methoxy content can be lowered still futher to 5 - 6% by a further treatment with an alcohol/ammonia mixture at a temp. less than 15 degrees C, the mol. wt. of the product reducing also to 120,000 - 160,000.