The Fortification of Bread with Lysine I. The Loss of Lysine During Baking

Abstract

The loss of lysine in bread due to baking was found to be about 15% by microbiological assay. The loss varied from 9.5 to 23.8%. Bread was baked from flour to which was added 0.5% DL-lysine · HCl or 0.25% L-lysine · HCl, amounts equivalent to 0.2% L-lysine. The destruction of added lysine was determined by comparison of the lysine content of this bread with that of loaves prepared from unfortified flour. In the bread to which DL-lysine · HCl was added the loss of L-lysine was found to average 11%, ranging from 2.4 to 21.8%. This loss was of the same order of magnitude as that found in the unfortified bread. Using the L-lysine · HCl-fortified formula, loss was considerably higher, averaging 32% and ranging between 25 and 36.8%. Toasting a slice of bread reduced the lysine content by 5 to 10%. A similar loss occurred when bread became stale and dry.