GC-Recomposition-Olfactometry (GC-R) and multivariate study of three terpenoid compounds in the aroma profile of Angostura bitters

Abstract

Foods and beverage aroma results from multicomponent mixtures of volatile compounds present in the food that interact with olfactory receptors and produce a perceptual response in the brain. However, the perceptual interactions that occur when complex odor mixtures are combined are not well understood. Here we used Gas chromatography-Recomposition-Olfactometry (GC-R) to better understand the role that individual compounds have on the perceived sensory aroma of bitters. Bitters are the concentrated alcoholic extract of flavorful plant materials with a wide range of complex sensory and chemical aroma profiles that have not been extensively studied. Previously, we demonstrated that Angostura bitters are characterized by complex aroma attributes described as cola, ginger, orange peel, and black pepper and that the volatile composition of Angostura bitters is predominantly composed of terpenoids. Using GC-R to create in-instrument mixtures of the Angostura headspace extracts, the sensory attributes of Angostura extracts with linalool, α-terpinyl-acetate and caryophyllene omitted were evaluated. The omission experiments demonstrated direct and indirect effects of the individual compounds on the aroma attributes of Angostura bitters, through masking, additive, and synergistic interactions. Caryophyllene in particular, which was present in the headspace extracts at concentration only slightly above sensory threshold levels, had a large and unexpected impact on the sensory properties of the mixtures and may be most responsible for the aromas associated with the whole sample. The GC-R and statistical approaches used here provided valuable tools to reveal relationships among individual compounds and aroma attributes of foods that have not been currently theorized using existing analytical approaches.

Figure 1

GC-MS chromatograms of (top) Mixture A, the control, uncut sample; and (bottom) Mixture E, with linalool, α-terpinyl acetate, and caryophyllene excluded from the reconstitution.

Figure 2

Differences in aroma qualities of mixtures with volatiles excluded compared to the control mixture. Decreases in descriptor count for experimental conditions highlighted in yellow, increases in descriptor count highlighted in magenta.

Figure 3

Correspondence analysis biplot of mixtures (blue circles, blue text) and descriptor counts (red triangles, black text). Dimension 1 (x) Variance explained = 37.2%, Dimension 2 (y) variance explained = 27.6%. Mixture A: control, uncut sample; Sample B: linalool omitted; Mixture C: α-terpinyl acetate omitted; Mixture D: caryophyllene omitted; Mixture E: linalool, α-terpinyl acetate and caryophyllene omitted.