Cereal Chem 55:481 - 488.  |  VIEW ARTICLE
High-Pressure Liquid Chromatographic Method for Evaluating Free Lysine Stability in Lysine- Fortified Wheat-Flour Products.

J. J. Warthesen and P. L. Kramer. Copyright 1978 by the American Association of Cereal Chemists, Inc. 

A rapid high-pressure liquid chromatographic method was developed to quantify free lysine in lysine- fortified foods. Free lysine was extracted from fortified wheat flour or fortified wheat-flour products and reacted with dansyl chloride. Didansyl lysine was separated by reverse-phase high-pressure liquid chromatography and detected by monitoring absorbance at 254 nm. Added lysine was stable in wheat flour heated at 100 C for 2 hr. With 10% added glucose and 10% added water, only 19.1% of the added lysine was recovered after 2 hr at 100 C. Doughs made with fortified flour and various carbohydrates were baked at 190 C for 15 min. Recoveries of lysine were 85.5% with cellulose, 70.6% with sucrose, and 20.9% with high-fructose corn syrup. Yeast bread made with flour fortified with 0.5% lysine hydrochloride gave lysine recoveries of 23% from the crust portion of the bread and 97% from the interior portion, with an overall recovery of 85% from the loaf. Breads made with sucrose or high-fructose corn syrup showed no difference in free lysine stability.