Non-destructive Analysis of Soluble Sugar Components in Strawberry Fruits Using Near-infrared Spectroscopy

The non-destructive determination of soluble solid content (SSC), as well as the glucose, fructose, and sucrose concentrations, in strawberry cultivars, including 'Akihime', 'Benihoppe', and 'Sachinoka', using near-infrared (NIR) spectroscopy was examined. Soluble sugars in the cultivars at different maturing stages were analyzed enzymatically and then calibrated against the NIR spectra. The optimal wavelength range for all components was 700-925 nm. The spectral pretreatment such as second derivative and multiplicative scatter correction showed no improvement on the calibration accuracy. The calibration results of the three cultivars analyzed as one group determined R 2 and standard error of prediction for SSC (0.86; 0.9%), glucose (0.74; 5.6 mg.g(-1) fresh weight (FW)), fructose (0.50; 6.3 mg.g(-1) FW) and sucrose (0.51; 12.5 mg.g(-1) FW) concentrations to be as good as those determined for each cultivar. Therefore, the NIR non-destructive measurement technique using a wavelength range of 700-925 nm is applicable for the prediction of not only SSC but also the concentrations of each sugar component in strawberries, irrespective of cultivar.