An analytical and sensory evaluation of the aroma volatiles of Tuber gibbosum

Graduation date: 1986The aroma of Tuber gibbosum, a native Oregon truffle, was\ud characterized using two distinct techniques. Volatile aroma\ud constituents were identified by chemical analysis, and sensory\ud characteristics were determined by examining response of the\ud general populace to the truffle aroma.\ud Truffle samples from four maturity ranges, as determined\ud by microscopic examination of each specimen for spore maturity,\ud were compared for amounts and types of aroma volatiles present.\ud Aroma volatiles of frozen specimens of T. gibbosum were sampled\ud using a headspace concentration technique. Volatile compounds\ud were analyzed by gas chromatography/mass spectrometry/data system\ud (GC/MS/DS) and the total volatile profile was found to contain up\ud to 20 compounds, depending on sample treatment and maturity.\ud Seven compounds were found to be the major aroma constituents and\ud were selected for further investigation. These 7 compounds were\ud identified from their mass spectra and the identities\ud substantiated by determining their Kovats retention indices. Amounts of volatile compounds present in each sample were\ud determined by capillary gas chromatographic (GO analysis using an\ud internal standard of n-tridecane for quantitative determinations.\ud The major aroma constituent for all the samples was oct-l-en-3-ol,\ud representing about 50% of the total aroma profile. The other 7\ud major components were 8- and 6-carbon alchols, ketones and\ud aldehydes.\ud Quantitative data for all samples and components were\ud analyzed statistically. A descriptive model for truffle maturity\ud was derived based on the amounts of 5 of the 7 compounds, and the\ud sum of the amounts of the 7 major constituents.\ud A comparison of volatiles from ascorbic acid treated and\ud untreated control truffle samples indicated an apparent reduction\ud in the amounts of several compounds.\ud The examination of public response to the aroma of T.\ud gibbosum was conducted as part of a display on truffles at the\ud Oregon Mycological Society Mushroom Show. The aroma of this\ud truffle, and three other native Oregon truffles were rated for\ud desirability and preference. Results indicate T. gibbosum was not\ud the favored sample, but was liked by about 2/3 of the population.\ud Comparison of responses by males and females showed no differences\ud for individuals liking the truffle aromas. However, females rated\ud the truffle aromas of 3 of the 4 species as more unpleasant than\ud did males