340 INOSITOLS 



often used dilute hydrochloric or sulfuric acids to treat the whole seed or 

 individual fractions of the seed, but other reagents have also been used. 

 From these extracts, various phytate salts have been precipitated and free 

 inositol obtained by hydrolysis of the phytate salt. 



B. CORN STEEPWATER AS A SOURCE OF INOSITOL 



Because of the relatively high concentration of contained phytate and 

 the large volume of raw material available, corn steepwater has proved to 

 be a highly satisfactory source of inositol. At least two commercial pro- 

 ducers of inositol are known to have developed processes utilizing corn 

 steepwater as a basis for the isolation of the natural vitamin. 



Steepwater is obtained during the process for the industrial wet-milling 

 of corn. Shelled corn entering the wet-milling plant is first soaked in a 

 warm, dilute, aqueous sulfur dioxide solution. This operation softens the 

 kernel and facilitates the subsequent separation of hull and fiber, germ, 

 gluten, and starch. The presence of sulfur dioxide in the steepwater inhibits 

 the action of microorganisms on the grain, and the liquid medium com- 

 pletes the cleansing of the kernels before milling. Most important, the 

 effect of the steeping process is to remove the water-soluble and acid- 

 soluble substances present in corn, phytates being included in this category. 

 Soluble protein, sugars, gums, and similar organic compounds, as well as 

 inorganic substances, are present in the steepwater along with phytate. 



In the form of phytic acid and its salts, inositol ordinarily constitutes 

 approximately 2% of the steepwater total solids. Precipitation of the 

 phytate in steepwater, hydrolysis of the phytate, and isolation of inositol 

 from the hydrolyzate are the steps involved in current industrial processes 

 for the preparation of inositol. 



C. PRECIPITATION OF PHYTATE FROM CORN STEEPWATER 



The phytate in steepwater is effectively separated by the addition of a 

 slurry of slaked lime which reacts with the soluble phytate present in the 

 steepwater to precipitate an insoluble phytate salt. Steepwater itself con- 

 tains calcium, magnesium, iron, sodium, and potassium; consequently 

 free phytic acid as such undoubtedly is not present in steepwater. Rather, 

 it appears probable that the phytate is present as soluble partial salts of 

 calcium, magnesium, iron, sodium, and potassium. Thus, the phytate 

 product precipitated from corn steepwater by the addition of lime is not 

 a pure calcium salt of phytic acid but is a mixed salt which contains other 

 metal ions present in steepwater, as well as some protein. 



In the precipitation step,^ lime is usually added until the steepwater is 

 brought to a pH of 5 to 7. The resultant heavy slurry is then filtered, and 



6 F. A. Hoglan and E. Bartow, Ind. Eng. Chem. 31, 749 (1939). 



