Chemical preservatives in foodstuffs. III Hexamethylenetetramine as mold inhibitor and the antagonistic action of amino acids

Abstract

Growth and respiration tests carried out on Aspergillus, Cladosporium and Penicillium molds have shown that certain amino acids such as 1-tryptophan and 1-cysteine and certain sulphydryl compounds such as glutathione and thioglycollic acid counteract the inhibitory action of hexamethylenetetramine. In the absence of hexamethylenetetramine, these compounds inhibit the growth of the molds. The dependence of the antagonistic action on the amino acid concentration differed for 1-cysteine and 1-tryptophan. The respiration of the mold was a maximum when equimolar concentrations of 1-cysteine and of the formaldehyde formed by the decomposition of hexamethylenetetramine were present in the culture media. The antagonistic effect of 1-tryptophan increased continuously with increasing concentration until the rate of oxygen consumption was the same as in the control test with no hexamethylenetetramine or antagonist present. The antagonistic effect of these four compounds on hexamethylenetetramine or on formaldehyde is evidently due to chemical interaction. The inhibitory effect of hexamethylenetetramine on the microbial cell may at least partly be due to its ability to inactivate enzymes such as the dehydrogenases.