Application of miniaturized near-infrared spectrometer for indirectly determining flesh thickness of intact polished coconut.

Consumers prefer polished coconut with a certain flesh thickness that is associated with maturity. At present, sorting mature polished coconuts is conducted manually. A portable near-infrared spectrometer in the range 900-1700 nm was adopted to determine the flesh thickness non-destructively. Averaged near-infrared spectra scanned in diffuse reflectance mode in three sections of the coconut bottom were used to create the predictive model using partial least squares regression. Samples from two harvests of the polished coconut were used. The first harvest samples were used to build and validate the model, and the second harvest samples were used to test the model performance independently. The final validated model, based on the samples from two harvests, provided acceptable performance, with values for the correlation coefficient, standard error of cross-validation, and bias of 0.89, 0.68mm, and -0.006mm, respectively. The near-infrared absorbance contained only shell spectral information that was confirmed by testing the penetration depth....