What is the best method for preserving the genuine black truffle (Tuber melanosporum) aroma? An olfactometric and sensory approach

•Freeze-drying arises as the most suitable preservation method.•2-acetylpyrrolyne is a marker of the drying process.•Any freezing step involves the presence of off-odour methional.•Frozen and canned products are far from the genuine black truffle aroma.

The aim of this work was to evaluate the effects of different preservation methods (freeze-drying, hot-air drying, freezing and canning) on the aroma profile of T. melanosporum truffles. Volatile organic compounds (VOCs) were extracted by solid-phase microextraction (SPME) and analysed by gas-chromatography olfactometry to monitor changes occurring in key-aroma compounds. Samples were also submitted to descriptive sensory analysis by a panel of trained judges, with the aim of correlating both sets of data. Freeze-drying − and to a lesser extent hot-air drying − were the only treatments able to retain key-compounds such as dimethylsulphide (DMS) and dimethyldisulphide (DMDS), evoking the aroma typically associated with fresh truffle. Principal component analysis (PCA) performed on the descriptive data showed the sensorial proximity between fresh and freeze-dried truffle, and also the differences between them and those frozen and canned. Despite some differences in the odour volatile profile of fresh and freezed-dried truffles (mainly the lack of 2,3-butanedione and branched ethyl esters), freeze-drying is the most suitable technique for preserving the overall original aroma of fresh truffle. Several key-odour compounds − mainly unsaturated linear chain carbonyl compounds, sulphur and pyrrole derivates − emerge as biomarkers of the studied technologies.