Dutch Gouda cheese has a unique taste (pronounced HOW-dah in the Netherlands but Goo-dah everywhere else). Most of the chemicals that make up this unique taste have been identified. The bitter taste is due to CaCl2 and MgCl2 plus various peptides derived from incomplete digestion of milk protein. The sour taste is due to lactic acid and phosphates. The salty taste comes from sodium chloride, sodium phosphate and the amino acid L-arginine. Monosodium l-glutamate and sodium lactate contribute the umami taste. (The five tastes are sweet, salty, sour, bitter and umami.)
Combinations of all these compounds at the appropriate concentrations mimicked the taste of Gouda cheese but something was missing. The "mouthfulness," and the complexity of the mature cheese was not present in the artificial concoctions. The missing taste is called the kokumi sensation.
A Sense of Smell
Toelstede et al. (2009) have found the missing chemicals. They mostly consist of various γ-L-glutamyl dipetides such as γ-Glu-Glu, γ-Glu-Gly, γ-Glu-Gln, γ-Glu-Met, γ-Glu-Leu, and γ-Glu-His. The structure of γ-Glu-Glu is shown below.
Most people don't realize that peptides and amino acids can impart very powerful tastes. Monosodiun glutamate (MSG) is an obvious example. So is aspartame, a powerful sweetener that's a modified tripeptide (Asp-Phe-Ala methyl ester).
Isn't biochemistry wonderful?
Here's a tough question. Let's say you could identify, with absolute certainty, all the chemicals that make up the taste of Gouda cheese. Let's say you make them in a lab and mix them with tofu and get something that tastes exactly like Gouda cheese. Would there be some people who want to ban that artificial Gouda cheese because it has chemicals? Would those same people be happy to eat the "natural" cheese because it doesn't have chemicals?
Toelstede, S., Dunkel, A., and Hofmann. T. (2009) A Series of Kokumi Peptides Impart the Long-Lasting Mouthfulness of Matured Gouda Cheese. J. Agric. Food Chem., 2009, 57 (4), pp 1440–1448. [DOI: 10.1021/jf803376d]