Non-Destructive Grading of Premium Litchi using Near Infrared Spectroscopy Premium litchi grading by NIRS

Abstract

This study aims to evaluate the feasibility of near-infrared spectrum for grading of premium litchi. Paa chid litchi were used as samples. The classification of litchi between the premium fruit with small seed-large pulp and the normal size litchi was performance using principal component analysis (PCA). The quantity of litchi based on the values of total soluble solid (TSS) and titratable acidity (TA) were predicted by using partial least squares (PLS) regression. The NIR spectra were acquired from 3 positions of litchi which were seed stalk-side, site-side and tip-side, at wavenumber of 12000-4000 cm-1 with reflectance mode. The results showed that PCA could effectively discriminate the premium litchi from the normal one using the spectra obtain from the side-site of litchi with accuracy 96.78%. For litchi quantity determination, the best PLS models for TSS and TA prediction were obtained with R values of 0.90 and 0.92, respectively, and root mean square error of cross-validation of 0.414 and 0.038%, respectively. These results indicated that NIRS is a promising technique for rapid and non-destructive analysis for grading premium litchis and determining the litchi anality based on TSS and TA values.