Characterization of Aroma-active Compounds in Four Yeast Extracts Using Instrumental and Sensory Techniques.

GC-O coupled with sensory analysis and partial least squares regression (PLSR) analysis, led to the identification of the odorants responsible for the different flavors of four yeast extracts. Sensory analysis showed that LA00L had intense sulfurous attribute, and LA00 was characterized by fatty and green notes, FA31 exhibited the floral odor, while KA02 had strong phenolic, animal, fermented, roasted, and caramellic notes. A total of 37 key aroma compounds with OAVs greater than 1 were determined. 2,4-di-tert-butylphenol and methional were the most potent aroma compounds. In addition, the key aroma compounds in LA00L were nonanal, dimethyl disulfide and γ-decalactone. Octanal, dimethyl disulfide and benzeneacetaldehyde were the key aroma compounds in LA00. In FA31, styrene, benzeneacetaldehyde and acetophenone were the key aroma compounds, while indole, 2-methoxyphenol, benzeneacetaldehyde and p-cresol contributed significantly to the aroma of KA02. PLSR showed that p-cresol and indole were significantly responsible for the phenolic and animal notes inducing the off-flavor (yeasty odor) of yeasty extracts. More significantly, indole was first reported to have an important effect on yeasty odor.