Truffle, black

Black truffles - http //commons.wikimedia.0rg/wiki/File Truffles black Croatia.jpg uselang=en-gb... 

Harki, E., Bouya, D., and Dargent, R., Maturation-associated alterations of the biochemical characteristics of the black truffle Tuber melanospomm Vitt., Food Chem., 99, 394, 2006. 

The volatile constituents of canned Black Perigord Truffles (Tuber Melanosporum) were analysed by dynamic headspace concentration gas chromatography - mass spectrometry. A total of 36 compounds were identified and described for the first time as canned black truffle aroma constituents. The modification of flavor and the possible formation of the compounds due to the heating treatment are discussed. 

Black Perigord truffles (Tuber Melanosporum) are underground mushrooms that grow in symbiosis with certain trees, especially... 

We have previously carried out studies on fresh black truffle aroma by strip and trap / dynamic headspace analysis. Experiments were carried out with truffle flesh (1,2), entire truffles ( Talou,... 

Since cooks report that processed black truffles have a particular aroma which is different and stronger than fresh truffle aroma, we decided to investigate the volatiles of canned black truffles. 

The aim of this study was to identify the volatiles of canned black truffles by capillary gas chromatography - mass spectrometry in order to assess the modification of aroma due to the thermal processing. 

TALOU ET AL. Aroma Composition of Canned Black Truffles... 

Material. Fresh Black Perlgord Truffles ( Tuber Melanosporum) were purchased by Pebeyre Ltd.(Cahors, France), a company specialized in truffle marketing. These truffles were collected mainly in the South East of France. They were fully ripe (3) and released their... 

Sensory Validation of Sampling and GC Techniques. The sensory evaluation was carried out by a panel of three judges (employees of Pebeyre Ltd.). For this study, an external odor port was attached to the gas vent of the D.C.I. system. After the thermal desorption of the volatiles from the trap, the rotary valve was positioned so that the unresolved aroma isolate went to our sniffing port. The response was mesured as similarity or dissimilarity to canned black truffle aroma. 

The volatile isolate desorbed and sensorially assessed at our odor port was described as typical of processed black truffle, showing that the Tenax had adsorbed and desorbed volatile components responsible for canned black truffle aroma. 

A typical total ion current chromatogram of the Tenax trapped canned black truffle (Tuber Melanosporum) juice volatiles is shown in Figure 2. The compounds identified by GC-MS are listed in Table I in the order of elution from the GC column with their characteristic mass spectral data. The identification of these compounds was based on comparison of the mass spectra obtained with those stored in the NIH/EPA library and also with those of authentic compounds. Moreover, an additional search of published standard mass spectra to confirm the identity of unknowns was undertaken (16). 

The major volatile components identified in canned black truffles were alcohols and carbonyls, including acetaldehyde, acetone, 2-butanone, 2-methyl-l-propanol and the two methyl-1-butanols. Also in relatively large amount was dimethyl sulfide. 

Figure 2. Reconstructed capillary GC-total ion current chromatogram of headspace volatiles of canned black truffle (Tuber Melanosporum) juice.

Table I. Volatile compounds identified in canned Black Truffle...

The headspace technique developed in the present study to isolate volatiles from canned black truffles performed satisfactorily. The aroma isolate obtained was described as typical, and 36 compounds were identified for the first time as canned clack truffle constituents. The formation of the major part of them could be correlated to the thermal treatment applied. 

Talou, X, Delmas, M., Gaset, A. (1987). Principal constituents of black truffle Tuber melanosporum) aroma. J. Agric. Food Chem., 35, 774-777. 

The volatile compounds in the atmosphere of cold stored Black Perigord Truffles (Tuber Melanosporum) were adsorbed onto a Tenax trap by means of a vacuum pump. The efficiency of the sampling method was sensorially validated. The volatiles eluted from the trap by heat desorption were analysed by capillary gas chromatography - mass spectrometry. A total of 26 compounds was identified. Their contribution to the final aroma impression was discussed. 

The atmosphere of cold stored Black Truffles is particularly rich in volatile compounds which impart the truffle aroma. We therefore developed a modified gas headspace sampling procedure for their isolation. 

The aims of this study were to evaluate the efficiency of our sampling method for trapping volatile components important to the aroma of Black Perigord Truffles, eind the cinalysis of minor volatiles via their identifcation with capillary gas chromatography-mass spectrometry. 

Sensory Evaluation of the contribution of identified compounds to the aroma In order to identify those compounds mainly contributing to the characteristic flavor of the Black Truffle, the odor of the individual components of the headspace analysis were tested by a panel of eight judges (trained in sensory evaluation of truffles). The compounds tested were diluted in vegetable oil, in a range of concentrations from 30 to 300 ppm. 5 point scales (5 = exceptionally good full truffle aroma, 1 = not different from solvent) were used for flavor imitation and intensity. 

Identification of volatiles compounds A typical total ion current chromatogram of the Tenax trapped Black Truffle (Tuber Melanosporiim) volatiles is shown in Figure 4. 

Table I. Volatiles identified in atmosphere of cold storage for Black Truffles (Tuber Melanosporum)...

The major advantage of the seunpling technique developed, was that some trace chemicals could be trapped tind described for the first time as Black Truffle aroma constituents. In particular, some compounds, important flavor contributors, generally appearing in small concentrations, such as benzaldehyde, propanal, ethyl acetate, anisole or dimethyl disulfide - previously identified in Shiitake mushrooms (9) - could be characterized. This was also the case for three aromatic compounds, toluene, xylene and ethyl benzene, well known as raw vegetable constituents (1 ). In addition, two aliphatic esters, isopropyl and sec-butyl formates, and one cyclic sulfur compound (2-formyl thiophene) previously reported respectively in plums and apples (W) and in coffee and bread products (n) were identified. 

Relative odor contribution of components Considered individually, none of the compounds identified duplicated the flavor of the Black Truffle. However, according to the judges, dimethyl sulfide was determined to have a great Importance to the final aroma Impression. In the same way, 2-butanone ind anisole were found to be responsible for an off-flavor characteristic of over-mature truffles. 

An industrial application of this result was the elaboration of the first Nature-Identical Black Truffle aromatizer (13). This product was tested with success during one year by well known french cooks in their restaurant. Culinary tests confirm the good organoleptic quality of the flavored products obtained, both for cold or hot dishes. 

The headspace sampling technique developed in the present study to collect volatiles from cold stored Black Truffles performed adequately. Indeed, the aroma Isolate obtained was described as typical, and 11 minor compounds could be described for the first time as Black Truffle aroma constituents. Moreover, these results allowed the formulation of the first Nature-Identical Black Truffle aromatizer. 

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