Writing in the Journal of Agricultural and Food Chemistry, German scientists report that six gamma-glutamyl peptides that appear to be mainly responsible for the so-called ‘kokumi sensation’ behind Gouda.
“As these gamma-glutamyl peptides might have important implications also to the taste profile of other dairy products, studies on the biogeneration of these kokumi peptides during cheese ripening are currently in progress,” wrote the researchers, led by Thomas Hofmann from the Technical University of Munich.
Gouda was first perfected by farmers in the village of Gouda in Holland about 800 years ago. According to background information in the journal, although many studies over the last three decades have attempted to elucidate the compounds responsible for the complex, long-lasting characteristic taste of the popular cheese, known as the “kokumi sensation”, the answers have eluded researchers until now.
TU Munich’s Hofmann and Andreas Dunkel, in collaboration with Simone Toelstede from the University of Münster, used molecular sensory science to show that a 44-week-matured Gouda cheese had a more pronounced ‘mouthfulness’ and long-lasting taste complexity than a four week old Gouda.
Further analysis using a combination of high performance liquid chromatography, mass spectroscopy, and gel permeation chromatography (GPC) enabled the identification of two classes of protein, 8 alpha-l-glutamyl and 10 gamma-l-glutamyl dipeptides as potential kokumi-enhancing molecules.
However, only the gamma-l-glutamyl dipeptides were found to “impart an enhanced kokumi sensation to the matured cheese, whereas none of the alpha-glutamyl peptides were found to be active”, said the researchers.
Among these peptides, the key kokumi molecules were proposed to be gamma-Glu-Glu, gamma-Glu-Gly, gamma-Glu-Gln, gamma-Glu-Met, gamma-Glu-Leu, and gamma-Glu-His.
This knowledge could be used to enhance the flavour of dairy products by technological means, said the researchers.
Source: Journal of Agricultural and Food Chemistry 2009, Volume 57, Issue 4, Pages 1440-1448, doi: 10.1021/jf803376d“A Series of Kokumi Peptides Impart the Long-Lasting Mouthfulness of Matured Gouda Cheese” Authors: S. Toelstede, A. Dunkel, T. Hofmann