Characterization of the Volatile Compounds in Raw and Roasted Georgia Pecans by HS-SPME-GC-MS

Volatile compounds are responsible for the characteristic aroma of raw and roasted pecans. Yet, much is unknown about the specific effects of roasting on pecan volatiles. In this study, the volatiles of raw "Desirable" pecans from Georgia and 3 roasted pecan samples (175 °C for 5, 10, and 15 min) were determined by HS-SPME coupled to GC-MS using stable deuterium-labeled volatiles as internal standards for quantitation. As expected, roasting markedly impacted the volatile profile of pecans: a total of 63 flavor-active compounds were identified in roasted samples, including 9 compounds not detected in raw "Desirable" pecans. Pyrazines, notable indicators of the Maillard reaction, were found only in roasted samples and demonstrated continual increases throughout observed roasting times. Furthermore, it was noted that hydrocarbon derivatives showed substantial increases with roasting, likely a result of the degradation of nonvolatile lipids. The observed changes correspond well to prior sensory investigations concerning the impact of roasting on pecan flavor, and explain increases in intensity for roasted, nutty, buttery, and sweet sensory traits. PRACTICAL APPLICATION: The results of this study document the volatile constituents generated during the roasting of pecans, and this may help formulators, who are trying to develop natural and artificial pecan flavors in new food products.