High-throughput color assessment of red raspberry puree

C. Baldassi, Y.Y. Lee, M. Dossett, S.D. Castellarin
Fruit color is a key parameter of red raspberry (Rubus idaeus L.) fruit quality and a focus of red raspberry breeding programs. Fruit color is commonly measured with the colorimeter, an instrument that measures one sample at a time. In breeding programs, large numbers of individuals may be screened, thus making color measurement very time-consuming. The principal aim of this project was to develop a high-throughput protocol for red raspberry puree color assessment using the digital phenotyping software Tomato Analyzer. Moreover, color parameters collected with different methodologies were correlated with total anthocyanins to analyze potential relationships between these pigments and color parameters. Raspberry puree samples were obtained in 2020 from the fruit of 32 genotypes. Samples contained in Petri dishes were measured with a colorimeter and Tomato Analyzer, while the same samples contained in 96-well clear plates were only analyzed with Tomato Analyzer. Parameter L* showed significant (p <0.001) and strong correlations (R=0.97) across all methods. Parameters a* and b* also showed significant correlations (p <0.001) across all methods, but while the correlations between the colorimeter and Tomato Analyzer using Petri dishes were weak (R=0.59 and R=0.37, respectively for a* and b*), the correlations between Tomato Analyzer using Petri dishes and plates were strong (R=0.98 for both a* and b*). These observations suggest the colorimeter and the digital phenotyping methods provide similar results for parameter L*, but not for a* and b*. The 96-well plates could be used to replace Petri dishes to conduct a high-throughput analysis of raspberry puree color. While the colorimeter did not detect significant correlations between a*, b* and total anthocyanins, both the methods based on Tomato Analyzer defined significant and negative relationships, suggesting the software might better identify color differences in red raspberry puree samples.
Baldassi, C., Lee, Y.Y., Dossett, M. and Castellarin, S.D. (2024). High-throughput color assessment of red raspberry puree. Acta Hortic. 1388, 281-286
DOI: 10.17660/ActaHortic.2024.1388.41
Rubus idaeus L., fruit color, colorimeter, digital phenotyping, Tomato Analyzer

Acta Horticulturae