The Study of Non-Destructive Measurement Apple's Firmness and Soluble solid Content Using Multispectral Imaging

Firmness and soluble solid content (SSC) are two important quality attributes. This researches investigated the feasibility of using multi-spectral imaging to non-destructive measuring the apple’s firmness and SSC. The spectral imaging in wavelength of 632nm、650nm、670nm、780nm、850nm and 900nm were captured. The Lorentzian distribution (LD), Gaussian distribution (GD) and Exponential distribution (ED) with three parameters were used to fit scattering profiles for all wavelengths. LD was found to be the best function for fitting gray distribution of the image. The multi-linear regression model using Lorentzian parameters for predicting apple firmness and soluble solids content were built using best single wavelength, double wavelengths, three wavelengths and four wavelengths. The best model with three wavelengths was able to predict apple soluble solid content with r=0.831, SEC=0.55 °Brix and predict apple firmness with r=0.880, SEC=0.52 N with four wavelengths. Experimental results show that the multi-spectral scattering imaging has high potential as a nondestructive and rapid method to assess fruit internal quality.