Nondestructive determination of solids and carotenoids in tomato products by near-infrared spectroscopy and multivariate calibration.

Tomato is an important player in the agricultural market. It is the second most consumed vegetable in the world and is a source of important micronutrients such as lycopene and beta-carotene. Recent research has demonstrated that these carotenoids can act as free-radical quenchers in the body and prevent aging, tissue damage, heart disease, and certain cancers. Besides these microcomponents, tomato is composed of soluble and insoluble solids. In industry, these solids govern factory yield and play a major role in the tomato trade. Nowadays, standard methods for determining tomato solids and carotenoids are time and labor consuming. In this work, we present the development of a simultaneous and nondestructive method for determining total and soluble solids, as well as lycopene and beta-carotene, in tomato products by near-infrared spectroscopy. PLS-1 was the calibration technique chosen. For spectra preprocessing, MSC and second derivative were applied. As variable selection techniques, the correlogram cutoff, the successive projections algorithm, the dimension wise selection, and spectra splitting approach were applied. Best models presented satisfactory prediction abilities evaluated through its RMSEP and r values: total solids 0.4157, 0.9998; soluble solids 0.6333, 0.9996; lycopene 21.5779, 0.9996; beta-carotene 0.7296, 0.9981.