Preparation of sodium strontium galacturonate from citrus products

Abstract

The present paper describes the convenient separation of galacturonic acid in the form of sodium strontium galacturonate from the hydrolyzates of citrus products, namely p ectic acid, p ectin, and the peel of oranges and of grapefruit. The method s are suitable for the preparation of large or small quantities of the salt, and it is believed that the preparation from pectic acid is commercially practicable.Sodium strontium galacturonate is obtained from pectic acid in about 90-percent yield without the use of alcohol or other organic solvent. By treatment of the salt with an equivalent quantity of aqueous sulfuric acid, a solution is obtained from which about 65 percent of the galacturonic acid may be crystallized in one crop, subst ant ially pure. Addi tional crops obt ained by the use of an organic solvent make the yield nearly quantitative.Pectin is not quite so satisfactory in the process as pectic acid, but because of its educational value, the preparation of sodium strontium galacturonate from pect in might be included in a course of laboratory instruction to demonstrate the presence of galact uronic acid in pectic substances. Both orange p eel and grapefruit peel may be used for the preparation of sodium strontium galacturonate, but the industrial use of these materials does not seem feasible at present on account of the large quant ities of relatively expensive enzyme required for hydrolysis. CONTENTS Page

Oxidation of galacturonic acid and of 5-keto-gluconic acid in alkaline solution

“…The development of relatively simple methods for the preparation of salts of galacturonic acid [1] 1 and of 5-keto-gluconic acid [2] makes these substances readily available for the investigation of possible uses. The preparation of L-tartaric acid (dextrorotatory)2 from 5-keto-gluconic acid and the preparation of n-arabo-trihydroxyglutaric acid from galacturonic acid are reported in the patent literature l3, 4].…”