Differentiation between aroma-related bioactives in native coldpressed rapeseed oils with desired sensory attributes and with a fusty/musty off-flavor using multivariate methods
A systematic quantitation of selected odorants using stable isotope dilution analysis (SIDA) was performed in six native cold-pressed rapeseed oils with desired retention of bioactives and desired sensorial attributes (“positive controls”, PCs), in nine native cold-pressed rapeseed oils eliciting a fusty/musty off-flavor (OFs), and in two rapeseed samples, from which two of the nine fusty/musty off-flavor oils were pressed. These data were used as basis to find marker compounds for the fusty/musty off-flavor by means of multivariate methods. Obtained data clustered pairwise in a heatmap clearly showed that all PCs and OFs were very similar to each other in their own group concerning the selected compounds. Additionally, data were statistically evaluated using principal component analysis (PCA). Based on selected compounds, a high accordance of PCs, in parallel to a clear discrimination to the group of fusty/musty off-flavor oils and to the two rapeseed samples, was achieved. In a biplot, compounds with the highest differences between the two oil groups were identified as 4-methylphenol, 3-methylbutanoic acid, 2-phenylethanol, 2-ethyl-3,6-dimethylpyrazine, and 2-methylbutanoic acid. Thus, these compounds can be seen as marker compounds for the fusty/musty off-flavor oils and the seeds and can, therefore, serve for quality control of the raw material within a quick routine method.