Quantitative studies and taste re-engineering experiments toward the decoding of the nonvolatile sensometabolome of Gouda cheese

The first comprehensive quantitative determination of 49 putative taste-active metabolites and mineral salts in 4- and 44-week-ripened Gouda cheese, respectively, has been performed; the ranking of these compounds in their sensory impact based on dose-over-threshold (DoT) factors, followed by the confirmation of their sensory relevance by taste reconstruction and omission experiments enabled the decoding of the nonvolatile sensometabolome of Gouda cheese. The bitterness of the cheese matured for 44 weeks was found to be induced by CaCl₂ and MgCl₂, as well as various bitter-tasting free amino acids, whereas bitter peptides were found to influence more the bitterness quality rather than the bitter intensity of the cheese. The DoT factors determined for the individual bitter peptides gave strong evidence that their sensory contribution is mainly due to the decapeptide YPFPGPIHNS and the nonapeptides YPFPGPIPN and YPFPGPIHN, assigned to the casein sequences β-CN(60-69) and β-CN(60-68), respectively, as well as the tetrapeptide LPQE released from α_s1-CN(11-14). Lactic acid and hydrogen phosphate were identified to play the key role for the sourness of Gouda cheese, whereas umami taste was found to be due to monosodium L-glutamate and sodium lactate. Moreover, saltiness was induced by sodium chloride and sodium phosphate and was demonstrated to be significantly enhanced by L-arginine.