Optical isomers of chloropropanediols: mechanisms of their formation and decomposition in protein hydrolysates
J. Velíšek, M. Doležal, C. Crews, T. Dvořákhttps://doi.org/10.17221/3527-CJFSCitation:Velíšek J., Doležal M., Crews C., Dvořák T. (2002): Optical isomers of chloropropanediols: mechanisms of their formation and decomposition in protein hydrolysates. Czech J. Food Sci., 20: 161-170.
Protein hydrolysates produced by hydrochloric acid hydrolysis were analysed for 3-chloropropane-1,2-diol and its enantiomers. It was found that (R)-3-chloropropane-1,2-diol and (S)-3-chloropropane-1,2-diol were present in the hydrolysates in equimolar concentrations. Model experiments with glycerol, triolein and soy lecithin heated with hydrochloric acid in solution showed that these materials were precursors of 3-chloropropane-1,2-diol and 2-chloropropane-1,3-diol and, as expected, yielded racemic 3-chloropropane-1,2-diol. Yields of 3-chloropropane-1,2-diols decreased in the order triolein > lecithin > glycerol. The mechanisms of 3-chloropropane-1,2-diol enantiomers formation during the production of protein hydrolysates are presented and discussed as well as the reaction pathways of their decomposition in alkaline media via the corresponding intermediates, (R)- and (S)-glycidol, respectively. Both epoxides are hydrolysed to glycerol and form a variety of products with hydrolysate constituents.Keywords:
chloropropanediols; chloropropanols; 3-chloropropane-1,2-diol; 2-chloropropane-1,3-diol; glycidol; MCPD; enantiomers; protein hydrolysates