# Black Truffle Aroma Evaluation: SPME-GC-MS vs. Sensory Experts
###### Abstract  
Nowadays, the truffle aroma attribute is not included as a quality parameter in the current recommendation that explains the truffle quality (UNECE standard 53 FFV3) and establishes the truffle commercial categories. However, the aroma is the main reason why truffles are worldwide appreciated. Indeed, more than 30 aromatic molecules compose it, and this is the reason why the human evaluation and identification of these odorants, without previous training, is quite subjective. Analytical techniques such as gas chromatography techniques, however, can establish an aromatic profile and detect potential aromatic markers. In this study, 16 fasting experts were trained to make more objective the truffle aroma evaluation and odorants identification. For this, a comparison between solid-phase microextraction gas chromatography coupled with mass spectrometry (SPME-GC-MS) and sensory expert evaluation was carried out in six sessions during different harvesting times in the black truffle season (December, January, and February). Both techniques were able to separate truffles depending on the harvesting time. Also, a list of volatile organic compounds related to the aromatic attributes was reported. This information will help to provide a more objective \(T\). _malanosporum_ truffle sensory evaluation. Tuberculosis, black truffle; trained panel; volatile organic compounds; sensory analysis +
Footnote †: journal: _foods_  
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a more objective evaluation could be carried out. These two guidelines describe the key to recognize, learn, and evaluate odor attributes in general. But, their application to black truffle aroma evaluations is necessary before considering the aroma as a quality parameter. A variety of analytical methods are commonly used for analytical aromatic compounds determination [11]. One of the most common methods used to extract the aromas is the solid-phase microextraction (SPME) technique. The principle of this sampling technique is to reach an equilibrium state in which the concentrations of volatiles are equilibrated between truffle samples and the gaseous phase above. At this equilibrium stage, the extraction of volatiles is performed exposing an SPME fiber in the head space of the sample for a specific time (usually 10-30 min) and at a specific temperature. Different types of SPME fibers have been used for truffle aroma extraction. However, 50/30 \(\upmu\)m divinylbenzene/carboxen/polydimethylsiloxane (DVB/Car/PDMS) is the most used [7; 8; 12; 13; 14; 15]. Once the volatile compounds are attached into the fiber, its content is analyzed via gas chromatography (GC) coupled with mass spectrometry (MS) or olfactometry (GC-O) [7; 8]. Both techniques are based on GC; the only difference between them is the detector used. MS has higher sensitivity, specificity, and accuracy for the analysis of VOCs compared to the flame ionization detector (FID) usually used in the GC-O technique. Nowadays, truffle commercialized categories are regulated by the marketing and commercial quality control of truffles standard (United Nations Economic Commission for Europe (UNEC) Standard FFV-53, United Nations, 2017) [16]. However, this is just a recommendation, not a mandatory norm that explains how to classify the truffle quality. This recommendation only classifies truffles according to their weight, morphological, and physical aspects in extra, first, and second classes. It also associates the scientific name of the different truffle species with their common names and defines the quality requirements for truffles after preparation and packaging. However, the aromatic properties, the most valued attribute in truffles, are not considered in any standard or legislation. Due to the highly specialized devices and knowledge required for chromatography and olfactometry, these methodologies are not quick and cheap to implement for truffle quality inspections in local fairs, cooking competitions or protected geographical indication schemes.