Italian cold-pressed hazelnut oils: conjoint analysis of sensory quality vs volatile profile

Cold-pressed oils, produced only by mechanical extraction, can be considered high quality products, almost comparable to virgin olive oils. Among these, cold-pressed hazelnut oil is highly appreciated by many consumers. This unrefined oil retains some volatile compounds, characteristic of the primary vegetable material (raw or toasted hazelnuts) and responsible of peculiar sensory notes that can be olfactory perceived (directly or indirectly). The aim of this study was to investigate the possible correlation existing between volatile profile and sensory notes in 10 samples of cold-pressed hazelnut oils, purchased directly from the Italian market. The sensory profile of the samples was defined by quantitative descriptive analysis (QDA®) and their evaluation was conducted by a panel of fully trained judges; the training of the panel was monitored and evaluated through the use of PanelCheck software. The volatile composition was determined by SPME-GC-MS, in order to identify all the volatile compounds responsible for positive (e.g. raw or toasted hazelnuts) or negative (e.g. burnt) sensory notes. Finally, all the chemical and sensory values were elaborated and interesting correlations among analytical data were obtained. In particular, peculiar sensory notes, as well as specific volatile molecules useful as possible markers of the cold pressed hazelnut oil quality of were evidenced. The research was carried out with the financial contribution of the Italian Ministry of Instruction, University and Research in the framework of the PRIN 2009 project ‘‘Innovative technologic applications to improve the extraction yield of virgin oils from olives and seeds and for rapid controls of their quality’’.