With these techniques, we have attempted to discriminate six mushroom varieties: golden needle (Flammulina velutipes), eryngii (Pleurotus eryngii), hen of the woods (Grifola frondosa), white mushrooms (Agaricus bisporus), shiitake (Lentinus edodes), and shimeji (Hypsizygus marmoreus). Although excluding shimeji, the volatile components for the other five mushroom varieties have been revealed with GC/MS (Table 1), no study has reported sensor-based discrimination of these six fresh mushroom types. Additionally, we have investigated the possibility of discriminating mushrooms using correlation coefficients (r) with the artificial mushroom flavors champignon and truffle flavors.2.?Experimental Section2.1.

Fresh Mushroom Samples and Flavor SamplesThe six fresh mushroom samples (each approximately 30 g) of shiitake, white mushrooms, golden needle, shimeji, eryngii, and hen of the woods, produced in different areas of Japan in each mushroom category, were purchased at retail stores on three different days (Figure 1a�Cc). After placing these mushrooms into 2 L sample bags (Flek-sampler, Omi Odor-Air Service Corporation, Shiga, Japan), the bags were then filled with dry nitrogen (G1 grade), and allowed to equilibrate for 30 min (generally equilibration was needed for 15�C60 min in the 2-L sample bag depending on the smell intensity) with the mushrooms still remaining in the sample bags (Figure 1d). Dry nitrogen was adopted to reduce the interference of moisture.Figure 1.Approximately 30 g of mushrooms used for measurements (a)�C(c) and the sample bag that was filled with dry nitrogen after placing the mushrooms inside (d).

Champignon and truffle flavors from Le Nez Du Vin (Editions Jean Lenoir, Provence, France), a collection of flavors used for learning Batimastat wine aromas, were used. To adjust the strength of its aroma to the measurement range of the sensors, 5 ��L of the truffle flavor or 5 ��L of the champignon flavor were left for 30 min in a 2-L sample bag filled with the dry nitrogen until the flavor reached equilibrium. For the champignon flavor, after leaving it for 30 min in a 2-L sample bag, the equilibrated gas was diluted to 1/25 concentration and then it was equilibrated by leaving it for another 30 min.2.2. Sample MeasurementsAfter the equilibrium, the FF-2A (Shimadzu Corporation, Kyoto, Japan), which is an odor recognition system equipped with 10 types of sensors with differing characteristics, was used to measure the samples. An outline of the measurement method using the FF-2A has been described in Figure 2 and previous reports [26�C30]. Sampling was performed for 1 min at the rate of 165 mL/min from the sample bag.