Dehydration Thermoprofiles of Amino Acids and Proteins

SUMMARY Dehydration thermoprofiles representing water evaporation from aqueous solutions of 22 naturally occurring amino acids were determined. 14 amino acids exhibited peaks of “bound” water beyond the evaporation peak of “free” water. The acidic and basic amino acids indicated no water retention. Exceptional water retention properties, 30%‐70% of the total water content as measured by peak areas, were exhibited by the nonpolar amino acids: isoleucine, leucine, methionine and valine. The methyl and methylene groups of these nonpolar structures seem to be responsible for the water retention properties probably due to hydrate formation. One explanation could be that as the temperature is raised to a critical point, the semicrystalline array around the nonpolar amino acid radicals collapses. Beef muscle tissue and egg albumin indicated strong water retention properties.