How can you know in the shop if you are buying an extra virgin olive oil? Who categorises it? There is an international regulation, but it appears that there are different perceptions of regulations in the EU. Researchers in an EU project have been looking at sensory assessment of olive oil, with a view to creating a common standard. Professor Erminio Monteleone of the University of Florence in Italy has taken part in the project.
Testing the vocabulary
The project group soon found out that oil-producing countries such as Spain, Greece and Italy use different vocabularies to describe sensory properties. They probably value the taste characteristics of oils from their own country more highly when they make an assessment, and thus arrive at different results. The project also tested the oils on sensory panels in other countries, including the Netherlands and England, and here too they found that the panels used different vocabularies to describe the oils.
The researchers in the project group therefore created a set of markers to describe the oils. Words used include green, yellow, tomato leaves, artichoke, apple, grass, bitterness and sharpness.
"Sensory description of oils appears to be far more complicated than either wine or cheese. Oils are used as ingredients, which makes them more difficult to compare than cheeses or wines," concludes Professor Monteleone. One of his greatest scientific interests is sensory properties that are vital for liking and positive perception. He recently visited the sensory and consumer research scientists at Nofima Mat, as part of a longer term collaboration between Nofima Mat and the University of Florence.
Consumers don't agree with themselves
Consumers' perception of oils has also proved to be vague. It was found that the more bitter the taste of the oils was, the less the consumers liked them. However when they were given information about which products they were tasting, they changed their minds and liked the bitter oils better. This can be explained by knowledge about a product giving expectations about sensory properties, and as a rule we like things better when we know what we are tasting.
The researchers also wanted to find out more about how oils were used in a meal. They held in-depth interviews with three famous chefs in restaurants in Italy. The chefs had to choose dishes they thought were best suited to various olive oils. They were presented with three olive oils with different intensities of given sensory properties. The three chefs largely agreed about which oils were best suited to particular types of dishes.
"Olive oil is an important product these days - in Norway too - but at the moment our knowledge about its sensory properties is limited. With the increasing national interest, it is important to learn from internationally recognised expertise in the field. We are very lucky in this case because, through substantial long-term international collaboration in sensory and consumer research, we have become good friends with one of the very best in the field, namely Professor Erminio Monteleone. Our follow-up plans are already being developed," says Principal Research Scientist Tormod Næs of Nofima Mat.
