DETERMINATION OF CAROTENOIDS IN TOMATO PRODUCTS USING VIS/NIR SPECTROSCOPY

Carotenoids analysis is complicated by their tendency to react with radical species, resulting in oxidative breakdown and isomerization during extraction. Hence, analysis methods should be rapid and avoid unnecessary exposure to high temperature, acids, and so on. The aim of this work to estimate carotenoid contents of processed tomato products non-destructively. The mean values obtained by visible and near-infrared Vis/NIR spectroscopy and by high performance liquid chromatography (HPLC) for eight carotenoid contents (ß-carotene, 5-cis lycopene, 13-cis lycopene, 9-cis lycopene, all-trans lycopene, zeaxanthin, lycoxanthin and total carotenoids) in four processed tomato products from five different brands were compared. The carotenoid contents were measured using HPLC, and these results were then used to develop partial least squares regression (PLSR) models to predict carotenoid components from Vis/NIR spectra of the same samples. A good correlation was found between HPLC measurements and the Vis/NIRs (590-790 nm) predictions for ß-carotene (RP2= 0.88), 9-cis lycopene (RP2= 0.86), total carotenoids (RP2= 0.84), 13-cis lycopene (RP2= 0.83), 5-cis lycopene (RP2=0.80), zeaxanthin (RP2= 0.80) to passable for all-trans lycopene (RP2= 0.70), but there was only a poor correlation (RP2= 0.20) for the lycoxanthin component. The overall results indicated that Vis/NIRs could be applied to assess carotenoid contents of different processed tomato products.