DETERMINATION OF TRYPTOPHAN IN FEEDSTUFFS - COMPARISON OF SODIUM-HYDROXIDE AND BARIUM HYDROXIDE AS HYDROLYSIS AGENTS

The tryptophan content of nine samples of food and feedstuffs was determined using two procedures differing mainly by the hydrolysing agent. For a given sample hydrolyses were conducted at the same time and in the same autoclave at 125 degrees C for 16 h after a purging of the apparatus at 100 degrees C for 5 min. Ba(OH)(2) hydrolysis yielded the highest values for tryptophan. As for NaOH hydrolysates, the tryptophan recovery evaluated from data obtained with Ba(OH)(2) hydrolysates and taken as reference varied from 74.5 to 98.2% with a mean of 88.8%. These values are identical to those reported in literature for recovery of tryptophan added to samples prior td their autoclaving in Ba(OH)(2) on NaOH but without purging at 100 degrees C. The tryptophan recovery corrected from losses of added 5-methyltryptophan varied from 95.3 to 106.8% with a mean of 102.3%. The efficiency of autoclave purging at 100 degrees C for the quantitative recovery of tryptophan from Ba(OH)(2) hydrolyses: would be due to a thorough deoxygenation of medium through boiling.