New approach for blueberry firmness grading to improve the shelf-life along the supply chain

Blueberry texture is one of the most commercially relevant quality traits. This parameter is closely associated with maturity and significantly affects post-harvest storage. Measuring small fruit firmness is challenging and critical due to the lack of a cheap, rapid, and easily interpretable standardized method of analysis. The digital durometer (53215 TP–Turoni, I), based on the Shore scale, has been found to be suitable for assessing berries hardness. In this study, samples were sorted according to their surface color: green, pink, red, ripe (completely blue), and overripe (completely pigmented, matte dark blue). Afterward, berries were classified into five categories based on the Shore scale. Every hardness value was linked to CIELAB coordinate color. In addition, every hardness category was related to total soluble solids content (TSS) and titratable acidity (TA). Results showed statistical differences in colorimetric coordinates and C color index among the firmness categories. Regression analysis showed a significative R2 coefficient between firmness and C color index (R2=0.79), and firmness and TA (R2=0.87). The findings highlighted how the digital durometer accurately divides fruits into maturity classes. This tool can be helpful as a non-destructive, accurate, rapid, and cheap procedure to sort blueberries into stages of ripeness. It may be a promising starting point for improving berries storage and shelf-life. With the digital durometer, the supply chain operators could uniformly divide batches with greater precision than would be obtained with skin color analysis only.