Kate Mosford of The Column spoke to Giorgia Purcaro of the Department of Food Science at the University of Udine, Italy, and Chiara Cordero of the Department of Drug Science and Technology at the University of Turin, Italy, about the sensory evaluation of olive oil and the benefits of a comprehensive approach.
Q: Olive oil is classified by law according to both the chemical composition and the sensory evaluation. Is olive oil the only food product analyzed by sensory evaluation?
Q: What does the sensory evaluation involve and what are the drawbacks?
GP: Sensory evaluation is fundamental in classifying olive oil within the specific commercial class, namely extra virgin, virgin, and lampante olive oil [Reg. CEE 2568/91, Reg CE 796/02; Reg CE 640/08].2–4
For example, extra virgin olive (EVO) oil, apart from respecting all the required chemical parameters, has to present a fruity aroma and no defects (muddy, fusty, rancid, musty, vinegary, or metallic) that have originated during olive or oil storage. Described in detail by both the European Regulation CEE 2568/912 (and following modifications) and by several International Olive Oil Council (IOC) documents (COI/T.20/Doc. No 15/Rev. 6; COI/T.20/Doc. No 13; COI/T.20/Doc. No 4),5–7 the sensory analysis is based on the judgement of a panel of assessors, composed of a minimum of eight testers (generally 12) headed by a panel leader, who has to motivate the judges, process the data, interpret results, and draft the final report.
The sensory assessment (both tasting and smelling) is performed according to codified rules, in a specific tasting room, and using a specific vocabulary (COI/T.20/Doc. No 4).7 The panel has to be continuously trained and the performance constantly evaluated, usually using reference samples provided by the IOC, to verify the reliability of the results and harmonize the perception criteria. However, despite a rigid codification of all the aspects of sensory analysis, several drawbacks can be pinpointed: (a) Organization of a panel session is not easy since panellists are usually employed in other jobs; (b) each session is very tiring, consequently only a limited number of samples (maximum of six) can be analyzed for each session; (c) low reproducibility has been observed among different panels, mainly as a result of uneven training, which is related also to the difficult availability of reference standards — in particular when presenting only one defect at a time. Therefore, an objective sensory evaluation is costly and time-consuming.8