Relationship between total solid content and red, green and blue colour intensity of strawberry (Fragaria x ananassa Duch.) fruits

The relationship between total solid contents and red, green, blue (RGB) colour intensity of full spectrum images of strawberry fruits were examined to develop an efficient, non destructive, cost effective and economical method to determine correct maturity stage of strawberry fruits for harvesting. The RGB colour intensity of the full spectrum images of strawberry fruits of cv. Chandler, RGB colour ratio and their respective total solid content (Brix value) at three different colour development stages; fully red coloured (FRC), three-quarter coloured (TQC) and half coloured (HC) were analyzed. Total solid contents of the strawberry fruits were significantly difference among the three colour developmental stages of fruits. The highest average total solid contents (7.7⁰ Brix ) was found in the fully red coloured strawberry fruits while the lowest total solid content (5.3⁰ Brix ) was found in the half coloured fruits. Total solid content of three-quarter coloured fruits was 6.1⁰ Brix. The sum of red, green and blue colour (R+G+B) intensities and the ratio of ((G+B-R)/(R+B+G))² were strongly correlated (R²=0.95 and 0.89 respectively) with the total solid content of strawberry fruits. This two indices could be used to decide the correct maturity stage of the strawberry fruits. With reducing the values of these indices, increase the TSS of fruits. consequently, the lowest values of indices indicates the highest total solid contents in fruits .

DOI: http://dx.doi.org/10.4038/jas.v8i2.5743

The Journal of Agricultural Sciences, 2013, vol.8, no2 p.82-90