Quantification of lycopene, beta-carotene and total soluble solids in intact red-flesh watermelon (Citrullus lanatus) using on-line Near Infrared Spectroscopy

摘要

A great interest has recently been focused on lycopene and beta-carotene, because of their\udantioxidant action in the organism. Red-flesh watermelon is one of the main sources of lycopene\udas the most abundant carotenoid. The use of near-infrared spectroscopy (NIRS) in post-harvesting\udhas permitted us to rapidly quantify lycopene, beta-carotene, and total soluble solids (TSS) on single\udintact fruits. Watermelons, harvested in 2013–2015, were submitted to near-infrared (NIR) radiation\udwhile being transported along a conveyor belt system, stationary and in movement, and at different\udpositions on the belt. Eight hundred spectra from 100 samples were collected as calibration set in\udthe 900–1700 nm interval. Calibration models were performed using partial least squares (PLS)\udregression on pre-treated spectra (derivatives and SNV) in the ranges 2.65–151.75 mg/kg (lycopene),\ud0.19–9.39 mg/kg (beta-carotene), and 5.3%–13.7% (TSS). External validation was carried out with 35 new\udsamples and on 35 spectra. The PLS models for intact watermelon could predict lycopene with\udR2 = 0.877 and SECV = 15.68 mg/kg, beta-carotene with R2 = 0.822 and SECV = 0.81 mg/kg, and TSS\udwith R2 = 0.836 and SECV = 0.8%. External validation has confirmed predictive ability with R2 = 0.805\udand RMSEP = 16.19 mg/kg for lycopene, R2 = 0.737 and RMSEP = 0.96 mg/kg for beta-carotene, and\udR2 = 0.707 and RMSEP = 1.4% for TSS. The results allow for the market valorization of fruits