Effects of Freeze-Drying Treatment on the Aromatic Profile of Tuber spp. Truffles

Abstract

The influence of lyophilization on the aromatic profile of two different truffles from Spain (Tuber melanosporum and Tuber aestivum) and a cultivated truffle (Tuber indicum) was evaluated by means of the headspace analysis. The volatile compounds were separated by gas chromatography and identified by mass spectrometry. The truffle aroma contained the characteristic compounds, such as 2‐methyl‐1‐propanol, 2‐methyl‐1‐butanol and dimethyl sulfide. Lyophilization and the subsequent rehydration of the truffles did not affect significantly the aroma profile of T. melanosporum; however, the volatile contents of T. indicum were slightly modified and those of T. aestivum changed after the treatment, in terms of reducing the 2‐butanol and 2‐butanone percentages and increasing the 2‐methylpropanal, 2‐methylbutanal and 3‐methylbutanal concentrations. From this study, we can conclude that truffle aromatic profile of the species T. melanosporum and T. indicum is mainly maintained after lyophilization whereas T. aestivum profile is substantially modified. Practical Applications Truffles are products with limited shelf life and their sensory properties are rapidly lost so that these fungi become a less valuable product in a few days. Losses of volatile compounds, oxidation and enzymatic reactions are a considerable problem during their storage. Several techniques have been used to preserve their sensory properties; however, the aroma profile is commonly modified as a result of high temperature processes or enzymatic reactions. This article describes the use of freeze‐drying as a form of processing technique for truffles (Tuber melanosporum, Tuber aestivum and Tuber indicum) to be stored. The use of lyophilization avoids the loss and degradation of volatile compounds because the process is performed at low temperatures. The results showed that the truffle aromatic profile of the species T. melanosporum and T. indicum was mainly maintained after lyophilization, whereas T. aestivum profile was substantially modified.

Potentials of truffles in nutritional and medicinal applications: a review

“…Al-Ruqaie demonstrated that freezing after blanching in 4% boiling NaCl solution is the most effective preservation method for maintaining the quality of T. claveryi and T. nivea [120]. Rivera et al recommended lyophilization as an adequate method to better preserve the aroma of T. melanosporum, while Palacios et al suggested that rehydration after lyophilization recovered the aromatic profile changed through lyophilization [121,122]. According to Tirillini et al [123], the addition of 10% linoleic acid (w/w) significantly reduced total bacterial load and enhance the nutritional value of truffle sauce.…”

Improvement of quality properties of cemen paste of pastirma by lyophilized red cabbage water extract

“…In previous studies, it has been reported that the lyophilization technique has significantly benefited in preserving phenolic compounds, color pigments (anthocyanins, carotenoids, etc. ), ascorbic acid, aroma components, and textural properties in fruits and vegetables (Bhatta et al., 2020; Gümüşay, Borazan, Ercal, & Demirkol, 2015; Palacios, Guillamón, García‐Lafuente, & Villares, 2014; Rajkumar et al., 2017; Rodrigues, Dos Santos, Bergamasco, & Madrona, 2018).…”

Truffle Research in the Post-Genomics Era

“…The effect of storage and freezing on the volatile organic compounds (VOCs) profile, and subsequently on truffle aroma, has recently been reported (Culleré et al 2013;Pennazza et al 2013). Given that lyophilisation is performed at low temperatures, limiting the loss and degradation of volatile compounds, Palacios et al (2014) have recently tested it as a process for preserving truffles during storage. These authors showed that the aromatic profile of the species T. melanosporum and Tuber indicum was mainly maintained after lyophilisation, whereas the aromatic profile of Tuber aestivum was highly sensitive to this treatment and substantially modified.…”