Identification of compounds responsible for the odorant properties of aromatic caramel

Aromatic caramel results from the heat treatment of sugars under specific temperature conditions. Because of its richness in aroma compounds and its pleasant organoleptic properties, caramel is widely used in the food industry. However, the composition of the volatile odorant fraction has not been completely elucidated. The aim of this work was thus to identify the volatile odorant compounds responsible for caramel sensory properties using a multivariate statistical technique. Four aromatic caramels differing in terms of their carbohydrate composition and cooking process were chosen. Odorant compounds were screened by gas chromatography-olfactometry (GC-O) and identified by GC-mass spectrometry (GC-MS). GC-O data were processed using a detection frequency method. A total of 76 odorant zones were detected and 49 aroma compounds identified, some of them being reported for the first time in caramel. In parallel, descriptive sensory profiles of the caramels were performed with a panel of ten trained assessors. Odour properties appeared to be closely related to the cooking properties of the caramel. The relationship between the intensities of sensory descriptors and the 76 odorant zones was modelled by partial least squares regression (PLS-R). The first PLS-R component explained 93% of the variance in sensory descriptors and 39% in GC-O data. Sensory descriptors were mainly separated on the first axis, opposing sweet-like descriptors (cooked-syrup, fruity, honey) to burnt sugar descriptors (strong, pungent, roasted). Heterocycles, carbocyclic compounds and acids appeared to be the principal odorants for burnt sugars. They were mainly described by empyreumatic notes in GC-O and correlated to burnt sugar descriptors in the PLS model.