Über die Chemie der Pektinstoffe: Tetra‐galakturonsäuren und d ‐Galakturonsäure aus dem Pektin der Zuckerrübe

Salts of galacturonic acid and their application to the preparation of galacturonic acid from pectic substances

“…It would therefore appear that the sample of {3-D-galacturonic acid was not entirely free from the alpha modification, but unfortunately we have not been able to obtain a sample of galacturonic acid that has a lower initial rotation than that reported Salts of Galacturonic Acid 83 here. 5 The initial specific rotation of the acid set free from sodium galacturonate is +21.9°, whereas for crystalline /3-D-galacturonic acid Ehrlich and Schubert reported +27° [8], and we found +31.1° [61.…”

“…Previously, Ehrlich and Schubert [8] reported [a] ~= +36. 02° without mutarotation, and Ono [9] reported [am = +38°, likewise without mutarotation.…”

“…Hence the new salt may be designated strontium a-D-galacturonate. 8. SODIUM CALCIUM GALACTURONATE, NaCa(CaHg0 7)3.6HzO This new crystalline salt (see footnote 3, page 78) was prepared by treating a solution containing 3 equivalents of galacturonic acid with 1 equivalent of sodium hydroxide and an excess of calcium carbonate.…”

“…Additional material was obtained by evaporation of the mother liquor. The yield of relatively pure crystalline sodium calcium galacturonate was approximately 750 g, or 85 percent of the galacturonic acid content of the 8 The product was supplied by the Calilornia Fruit Growers' Exchange, Ontario, Calif. o Usually about 1 part o( sodium bicarbonate is required for 4 to 5 parts of pectic acid, but the amount varies (or different lots. The proportion for each batch of pectic acid may be ascertained by mixing 5-g samples with various amounts of sodium bicarbonate and determining the pH of the mixture in 35 ml o( water.…”

“…Prior to the present investigation a crystalline sodium salt [8,9], an amorphous barium [10,11,12] and an amorphous calcium [8,9] salt were reported in the literature, but these compounds are not satisfactory for the separation of galacturonic acid from crude mixtures. Since a slightly soluble salt would provide a means for separating galacturonic acid directly from the hydrolyzates of plant materials, the preparation of a series of salts was undertaken with the object of obtaining a compound that could be used for separating galacturonic acid from the liquor obtained by the partial hydrolysis of such materials as apple pulp, citrus fruit pulp, and beet pulp.…”