Evaluation of gamma and electron-beam irradiation on the aromatic profile of black truffle (Tuber melanosporum) and summer truffle (Tuber aestivum)

Abstract

Abstract Changes in the aroma composition of truffles (Tuber aestivum and Tuber melanosporum) after electron-beam and gamma irradiation at doses of 1.5 kGy and 2.5 kGy were investigated by solid phase microextraction methodology (HS-SPME). In particular, the effect was evaluated on specific compounds chosen for their aromatic importance according to previously collected olfactometric data. Therefore, the main aim of this study is to evaluate the effect of electron-beam and gamma-irradiation on the aroma of different truffles. Some changes were produced by these treatments, although none were sufficient to be observed in a sensory test. However, some relevant conclusions were drawn from the data obtained from these analyses. In the case of Tuber melanosporum, the electron-beam treatment induces important changes in the aromatic profile while γ-irradiation did not result in any significant change. Most different samples had been irradiated with doses at 1.5 kGy of electron-beam. In the case of Tuber aestivum, gamma-irradiation induced the greatest aromatic differences in comparison with the non irradiated samples (considered as control samples). Again, a dose of 1.5 kGy had the greater impact on the truffle aroma. It is known that the irradiation process implies an oxidative degradation of fatty acids (lipidic oxidation). In this complementary research, higher levels of some of these carbonyls (hexanal in T. melanosporum and hexanal, E,E-2,4-nonadienal and nonanal in T.aestivum) were observed in the Tuber melanosporum samples treated with electron-beam and in Tuber aestivum samples treated with gamma-irradiation. Industrial Relevance Irradiation is recognized as a safe and effective method of preservation used to extend the shelf life of raw and processed foods in many countries worldwide. The main benefit of irradiation is widely accepted as eliminating microorganisms, insects or parasites capable of inflicting food spoilage and toxicity, thus replacing chemical fumigants. However, in many cases food irradiation is limited due to fatty acid decomposition and subsequent off-flavor development in the foodstuff. On the other hand, one of the most important problems of truffle storage is the preservation of taste and aroma, essential parameters for its quality. As a consequence, treatments such as the use of gamma rays or electron-beam irradiation are potentially attractive for improving the shelf life of truffles as long as they do not modify their aromatic characteristics. For this reason, we decided to research about the effect of these kinds of irradiation on the aroma of different truffles (Tuber melanosporum and Tuber aestivum).