Characterization of the key aroma compounds in Kung Pao chicken by molecular sensory science

Kung Pao Chicken (KPC) is a famous Sichuan cuisine with unique flavor. However, there is lack of thorough research about its flavor, which seriously limits its industrial production. Therefore, the aroma characteristics and the key aroma compounds of five commercial KPCs were investigated by sensory analysis combined with electronic nose, GC×GC-MS, gas chromatography-olfactometry-mass spectrometry (GC-O-MS), odor activity value (OAV) and odor-specific magnitude estimation (OSME). The results revealed that the typical aromas of KPCs were sweet, sour, sauce fragrant, spice, chicken and roasted flavor, especially sample A4. The volatile compounds of KPCs obviously varied among different brands. Orthogonal partial least squares discrimination analysis (OPLS-DA) successfully discriminated sample A4 from others and recognized 33 significantly different compounds. Based on OAV and aroma intensity (AI), 45 aroma-active compounds with OAV > 1 and AI > 2.5 were perceived in the five KPCs, in which 22 key aroma compounds were verified in sample A4 by aroma recombination and omission tests. Further correlation analysis found W1C and W5C as critical E-nose sensors to monitor the formation of KPC key aroma compounds. These results could establish the aroma database of KPC and provide the basis for its flavor stability during industrial production.