Optical and Chemical Profiling of Japanese Strawberries: Fluorescence Fingerprints, Imaging Features, and Quality Attributes Prediction

Abstract

New strawberry cultivars with unusual peel colors, such as white and peach, require thorough characterization to understand their quality traits. In this study, we examined three Japanese cultivars, ‘Kotoka’ (red), ‘Awayuki’ (peach), and ‘Pearl White’ (white), to investigate their differences in chemistry and optical properties. We measured the sugar content, acidity, and maturity index, and combined these with fluorescence spectroscopy and imaging under three LED lights (365 nm, 420 nm, and white). The fluorescence data showed clear differences between cultivars, in which the ‘Pearl White’ gave a strong near-UV peak around 290/325 nm, ‘Awayuki’ had a high far-red signal in 490/745 nm, and ‘Kotoka’ showed lower fluorescence overall. Imaging backed up these findings, with ‘Pearl White’ and ‘Awayuki’ looking brighter under UV while Kotoka appeared darker and more uniform. Texture analysis showed ‘Pearl White’ had a more uneven surface, while ‘Kotoka’ was smoother. The basic chemistry also matched these trends, as ‘Kotoka’ had the most sugar and acid, giving it a sharper taste, while ‘Pearl White’ had the highest maturity index and a milder flavor. These results demonstrate how fluorescence fingerprints and imaging features, when combined, can rapidly characterize strawberry types and assess their quality without damaging the fruit.