(cm) Early summer has arrived and the shelves of grocery shops are once again filled with home-grown strawberries. What makes up the quality of taste in this popular fruit? A collaborative study, carried out a few years ago but recently published, from ETH, the University of Applied Sciences (HES) in Sion and the Federal Research Centre in Conthey answers this question (1). The sensory quality is determined primarily by two major factors: the total amount of volatile components and sugar content.

That sugar would turn out to be a significant factor for a positive estimation of the sensory quality of a strawberry did not surprise ETH Professor Renato Amadò who led the study. However, the simple correlation between the total amount of volatile components and the quality of the fruit did surprise the food scientist. Although various components, such as methyl butanoate, methyl hexanoate or cis-3-hexenyl acetate are important, it seems that it is not the special composition of these that is determinant for the degree of esteem, but their quantities.

To investigate the quality of the strawberries, in a number of outlets of a supermarket chain, 120 customers were invited to taste the fruit in three consecutive years from 1997 to 1999 and assign marks on a scale from 1–9. In addition 10–15 practised testers determined such characteristics as flavour, acidity or firmness. When the results of their evaluation of these characteristics are compared with the results of the general quality assessment, flavour and sweetness emerge as useable quality parameters.

Sugar content and volatile components determine the sensory quality of strawberries. large

While half of the strawberries disappeared down the throats of the testers the other half was subjected to an instrumental analysis. Scientists analysed the sugar and acid content, as well as volatile substances. The latter are absorbed and caught in a closed flask by special fibres and then analysed by means of a gas chromatograph. The higher the sugar content and the higher the amount of volatile substances was, the higher the quality rating of the testers. This demonstrates that a relatively simple instrumental analysis can be used to determine quality.

Researchers gave the testers miscellaneous sorts of strawberries to taste. It turns out that there might be no point in arguing about taste because a sort called "Mara des bois" won in each of three years that were tested.