LV.—Phytin and phytic acid
Journal of the Chemical Society Transactions
THE name phytin has been applied to a white, amorphous substance which has been observed by Palladin (Zeitsch. Biol., 1895, 31, 199) to occur in the seeds of many plants, and yields inositol and phosphoric acid on hydrolysis under pressure with solutions of mineral acids or alkalis. An examination of the methods used in preparing the material investigated by previous workers left no doubt that different substances have been described as phytin, and that these substances were not always
... not always homogeneous. This conclusion was confirmed by the divergent published results representing the composition of phytin (compare Jegorov, Biochem. Zeitsch., 1912, 42, 433, and Plimmer and Page, Biochem. J., 1913, 7, 158). The acid obtained from phytin by the removal of the bases, calcium and magnesium, has been described as phytic acid, but no salt or derivative of it of undoubted purity has been isolated and analysed. Many of the substances described as phytic acid have been mixtures of phosphoric acid and an organic phosphoric acid. Schulze and Winterstein (Zeitsch. physiol. Chem., 1896, 22, 90 ; 1903, 40, 121) prepared phytin by extracting the faf-free seeds of Sinap-s nigra with 10 per cent. sodium chloride solution, coagulating the proteins by boiling, and, after cooling and filtering, precipitating phytin from the cold protein-free sodium chloride solution by heating. The substance thus obtained was identical in properties with that prepared by the methods recorded below. These authors mentioned the fact that phytin was less soluble in hot than in cold acetic acid, but did not develop this method of preparation. Winterstein (Ber., 1897, 30, 2299) prepared phytin by extracting seeds with dilute acetic acid and precipitating it from the solution by ammonia. The free acid was obtained by the removal of the bases by means of oxalic acid, and yielded inositol and phosphoric acid on hydrolysis under pressure with concentrated hydrochloric acid. The substances prepared by the latter methods were undoubtedly mixed with calcium and magnaiufn phosphates and phosphoric acid. Posternak (Compt. rend., 1903, 137, 202, 338, 439) extracted phytin from various fat-free seeds by means of very dilute hydrochloric acid, separating the substance by precipitation of the copper salt, decomposing the latter by hydrogen sulphide, and treating with alcohol the Syrupy acid substance obtained by the evaporation of the acid solution. The final product was soluble in water, and thus differed from that obtained by Schulze and Winterstein (Zoc.