Nondestructive Measurement of the Acidity of Strawberry Based on Wavelet Transform and Partial Least Squares

Vis/Near infrared reflectance spectroscopy appears to be a rapid and convenient non-destructive technique that can measure the quality and compositional attributes of many substances. This paper assesses the ability of NIR reflectance spectroscopy to estimate the acidity of strawberry. Spectra were collected from 65 samples and data was expressed as absorbance, the logarithm of the reciprocal of reflectance (log1/R). The absorbance data was subsequently compressed using wavelet transformation. Two models to predict the acidity in strawberry were constructed. A prediction model based on Wavelet Transform (WT) combined with Partial Least Squares (PLS) was found to be superior (r=0.856, RMSEP=0.026) to model only using partial least squares.