There is a saying that taste cannot be discussed. Research at Aarhus University has, however, shown that taste can be scientifically analysed and described - at least with regard to food's sensory qualities.

The objective of the investigation was to use a chemical approach to understand sensory variation as an effect of culinary preparation. Different varieties of the root vegetables Jerusalem artichoke and beetroot were harvested at different times during the season and prepared in different ways. The root vegetables were then analysed in the laboratory and by a panel of consumers.

There are several varieties of Jerusalem artichokes and beetroots that differ in shape and colour, but consumers do not know enough about them to take advantage of this variation. A better knowledge of the qualities of the individual varieties would enable consumers and producers to choose the variety that  meets their requirements, explains research assistant Vibe Bach from Aarhus University.

The tasting experience

Whether the consumer has a taste for a Jerusalem artichoke or beetroot involves more than the narrow definition of 'taste'. The perception of a food is defined as its sensory quality and this includes its taste, appearance, smell, texture and the sound made as it is eaten.

Vibe Bach investigated the  qualities of root vegetables with the aid of chemical analyses of root vegetable composition,  instrumental analyses, and sensory and consumer analyses. In her investigation she mapped how the quality of the root vegetables varied between varieties and developed during the season and during culinary preparation. It is the first time that a complete sensory description of Jerusalem artichoke and beetroot has been performed.

Vibe Bach discovered that texture, taste and colour were the most important characteristics for describing the quality of Jerusalem artichoke and beetroot and their suitability for different methods of preparation (raw, boiled, baked and pan-fried). The differences in quality were particularly seen between varieties, and the differences became less apparent when the root vegetables were prepared. The differences found were particularly related to texture and taste.

Oral sensation is important

- The suitability of Jerusalem artichoke and beetroot for all types of culinary preparation was related to crispness, juiciness, sweetness and intensity of colour, says Vibe Bach.

Crisp, rubbery, gritty, floury or watery - these sensations belong to the concept 'texture'. Texture can be assessed by the consumer and the sensory panel. We probably all know the difference between a flabby and a crisp carrot.

Texture can also be measured in the laboratory by, amongst other things, measuring cell wall structure, cell connectivity and physical hardness. The content of inulin in Jerusalem artichokes may also have an effect on the texture when Jerusalem artichokes are boiled, baked or pan-fried, because inulin is broken down during heating.

Sweet is good

The investigation also showed that the degree of sweetness means a lot for consumers' description of the taste of root vegetables. The degree of sweetness is very dependent on the harvesting date. For both Jerusalem artichokes and beetroot it was difficult to see a relationship between the sweetness as experienced by the consumer and the laboratory analysis of sugar content.

- The perception of sweetness can also be affected by the bitterness. We found that root vegetables can be perceived as being bitter and sweet at the same time, so the two characteristics do not exclude one another, says Vibe Bach.

The best root vegetables and increased consumption

To tempt and satisfy consumers, root vegetables generally need to be sweet and crisp and have a good, clear colour. They must not be floury or bitter, nor become discoloured during preparation. Producers can benefit from this knowledge when they choose varieties to plant or develop. Knowledge of the different qualities of root vegetables and characteristics can be used by consumers when preparing food in the kitchen.

- Root vegetables are healthy and it would improve the health of the population if more were eaten. If consumers have a better understanding of the variation in the selection of root vegetables and which of them they should choose for different purposes and culinary preparations it would improve the status of root vegetables in the kitchen and increase their consumption, suggests Vibe Bach.

The PhD project was part of a larger project, Gourmet Roots, which was funded by the Ministry of Food, Agriculture and Fisheries.

For further information please contact: Research assistant Vibe Bach, Department of Food Science, email: vibe.bach@agrsci.dk, telephone: +45 87154879