RESUMEN
Coppa Piacentina is an Italian protected designation of origin (PDO) dry-cured product obtained from the muscle of pork neck and ripened for at least six months. Metabolomics- and volatilomics-based strategies, combined with a chemical characterization of free amino acids were applied to identify biomarkers of long-ripened Coppa Piacentina PDO. Long ripening induced a significantly increase of total free amino acids, mainly represented by glutamic acid, involved in the umami taste perception. Untargeted metabolomics, performed using UHPLC-HRMS, allowed to identify 32 putative gamma-glutamyl-peptides, known as main contributors to the kokumi taste. Unsupervised and supervised multivariate statistics observed a clear modification of these peptides over the ripening, with gamma-glutamyl-peptides which significantly increased in long-ripened samples. A volatilomics-based strategy, conducted with GCxGC-MS, was then performed, and 93 different compounds were identified, with aldehyde and ketones deriving from the lipid auto-oxidation which increased according to ripening.
Asunto(s)
Aminoácidos , Péptidos , Ácido Glutámico , Aldehídos , BiomarcadoresRESUMEN
Ripening time is known to drive the chemical and sensory profiles of dry meat products, thus potentially affecting the final quality of the product. Starting from these background conditions, the aim of this work was to shed light, for the first time, on the chemical modifications of a typical Italian PDO meat product-namely, Coppa Piacentina-during ripening, to find correlations between its sensory quality and the biomarker compounds related to the progress of ripening. The ripening time (from 60 to 240 days) was found to deeply modify the chemical composition of this typical meat product, providing potential biomarkers of both oxidative reactions and sensory attributes. The chemical analyses revealed that there is typically a significant decrease in the moisture content during ripening, likely due to increased dehydration. In addition, the fatty acid profile showed that the distribution of polyunsaturated fatty acids significantly (p < 0.05) decreased during ripening, because of their high susceptibility to oxidation and conversion to intermediate and secondary molecules. An untargeted metabolomics approach, coupled with unsupervised and supervised multivariate statistics, highlighted a significant impact (prediction scores > 1) of lipid oxidation during ripening time, with some metabolites (such as γ -glutamyl-peptides, hydroperoxy-fatty acids, and glutathione) being particularly discriminant in predicting the changes observed. The discriminant metabolites were coherent with the progressive increase of peroxide values determined during the entire ripening period. Finally, the sensory analysis outlined that the highest degree of ripening provided greater color intensity of the lean part, slice firmness, and chewing consistency, with glutathione and γ-glutamyl-glutamic acid establishing the highest number of significant correlations with the sensory attributes evaluated. Taken together, this work highlights the importance and validity of untargeted metabolomics coupled with sensory analysis to investigate the comprehensive chemical and sensory changes to dry meat during ripening.