The colour of raspberry-based products is a key factor in consumer choice. Analytical determination of this parameter generally involves quantifying the anthocyanin content and/or evaluation using a colorimeter, procedures that are time-consuming when the analyses involve a large number of samples.

In this context, the aim of a recent study carried out by a group of Canadian researchers (Baldassi et al., 2024) was to develop a method for the rapid measurement of the colour of raspberry purées, evaluating the correlations between this parameter and the total anthocyanin content. In particular, colorimetric coordinates were collected with a colorimeter on 126 samples contained in Petri dishes and with the Tomato Analyzer Colour Test (TACT) module to evaluate the same samples prepared in Petri dishes and 96-well plates. An additional 425 samples were analysed using only 96-well plates. Total anthocyanins were extracted from all 551 samples.

The results show that although the colorimeter and TACT methods are not completely interchangeable, the TACT methodology is better at capturing colour differences between raspberry genotypes than the colorimeter.

In conclusion, the authors argue that, even if the correlations between the colour parameters measured with TACT and total anthocyanins are not strong enough to allow the development of predictive models, the use of TACT with 96-well plates instead of Petri dishes allows for the rapid measurement of the pure colour of raspberries with sufficient reliability.

Bibliographical references: C. Baldassi et al., Plant Methods, 20, 2024, 1-13