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Effect of lyophilisation in the black truffle (Tuber melanosporum) aroma: a comparison with other long-term preservation treatments (freezing and sterilization)

Marco, P., Campo, E., Oria, R., Blanco, D., Venturini, M. E.
Acta horticulturae 2018 no.1194 pp. 831-838
Tuber melanosporum, aldehydes, canning, dimethyl sulfide, experts, freeze drying, freezing, gas chromatography, odors, olfactometry, olives, sensory evaluation, solid phase microextraction, truffles, volatile compounds
The aim of this work was to evaluate the effect of different preservation methods (freeze-drying or lyophilisation, traditional freezing and canning) on the aroma profile of Tuber melanosporum truffles. Volatile compounds were extracted by a solid-phase microextraction (SPME) technique and further analysed by gas-chromatography olfactometry, in order to monitor changes occurring in key-aroma compounds as a result of the technology applied. Samples were also submitted to descriptive sensory analysis by a panel of trained judges, and to a preference (ranking) test by a group of truffle experts. Data revealed that the aromatic profile of T. melanosporum freeze-drying truffle was less modified with respect to the genuine truffle aroma than the rest of products. Freeze-drying was the only treatment able to keep truffle key-compounds such as dimethylsulphide (DMS) and dimethyldisulphide (DMDS), evoking a typical black olives aroma. On the contrary, several aldehyde compounds (methional, hexanal and Z-4-heptenal) appeared as important odour molecules, which could influence the final aroma of the product. Descriptive analysis and expert's ranking showed the relative proximity among fresh and freezed-drying truffle, and confirmed the deep changes occurring in aroma as a consequence of the traditional freezing and canning process. Freeze-drying arises therefore as an adequate technique to better preserve the original aroma of fresh truffle.