L. Aroma Blueprint: Potent Odorants Signatures in the Volatilome of High Quality Hazelnuts.

The volatilome of hazelnuts ( L.) encrypts information about phenotype expression as a function of cultivar/origin, post-harvest practices, and their impact on primary metabolome, storage conditions and shelf-life, spoilage, and quality deterioration. Moreover, within the bulk of detectable volatiles, just a few of them play a key role in defining distinctive aroma (i.e., aroma blueprint) and conferring characteristic hedonic profile. In particular, in raw hazelnuts, key-odorants as defined by are: 2,3-diethyl-5-methylpyrazine ( and ); 2-acetyl-1,4,5,6-tetrahydropyridine (); 2-acetyl-1-pyrroline (); 2-acetyl-3,4,5,6-tetrahydropyridine (); 3-(methylthio)-propanal (); 3-(methylthio)propionaldehyde (); 3,7-dimethylocta-1,6-dien-3-ol/linalool (citrus, floral); 3-methyl-4-heptanone (); and 5-methyl-(E)-2-hepten-4-one (). Dry-roasting on hazelnut kernels triggers the formation of additional potent odorants, likely contributing to the pleasant aroma of roasted nuts. Whiting the newly formed aromas, 2,3-pentanedione (); 2-propionyl-1-pyrroline (); 3-methylbutanal; (); 4-hydroxy-2,5-dimethyl-3(2H)-furanone (); dimethyl trisulfide () are worthy to be mentioned. The review focuses on high-quality hazelnuts adopted as premium primary material by the confectionery industry. Information on primary and secondary/specialized metabolites distribution introduces more specialized sections focused on volatilome chemical dimensions and their correlation to cultivar/origin, post-harvest practices and storage, and spoilage phenomena. Sensory-driven studies, based on principles, provide insights on the aroma blueprint of raw and roasted hazelnuts while robust correlations between non-volatile precursors and key-aroma compounds pose solid foundations to the conceptualization of .