Effect of ten amino acids on elimination of acrylamide in a model reaction system

Ten (10) amino acids (asparagine, aspartic acid, cysteine, glycine, glutamic acid, glutamine, methionine, leucine, tyrosine and lysine) were used to test their effect on elimination of acrylamide, when co-heating of 10 mol of acrylamide respectively with 0.1 mmol of amino acids at 160C for 15 min, acrylamide was eliminated from 7.4% (asparagine) to 94.4% (cysteine) at natural pH, and 11.4% (glutamic acid) to 94.8% (cysteine) at pH 7.0. It was found that cysteine, glysine and lysine showed much higher reactivity with acrylamide than the other seven amino acids. When the molar ratios of amino acid to acrylamide were increased to 60:1 for cysteine and glycine, and 80:1 for lysine, acrylamide in the reaction system was almost eliminated. The elimination efficiencies of the three amino acids for acrylamide were enhanced by addition of glucose. Liquid chromatography/time-of-flight mass spectroscopy showed that cysteine, glycine, and lysine adducted with two molecules of acrylamide, while the other amino acids except for glutamic acid (no adduct compounds were found) just adducted with one mole of acrylamide. This finding may partly explain why cysteine, glycine and lysine showed high capacity to reduce acrylamide content in high-temperature processing food.   Key words: Acrylamide, adduct, amino acids.