Application of VIS-NIR reflectance spectra for estimating soluble solid and lycopene content of open-field processing tomato fruit juice from irrigation and mycorrhiza treatments

Tomato (Lycopersicon esculentum Mill.) is one of the most important annual vegetable crops produced worldwide. Measurement, categorization and monitoring of specific characteristics of quality parameters in raw tomatoes and tomato-based products are extremely important for both the processing industries and consumers. In this segment of production and manufacturing, the application of quick, routine spectroscopy tests is becoming more frequent. There are two important characteristics of the processing tomato fruit, the soluble solids content (SSC) and the quantity of lycopene, which are greatly dependent on the cultivar, environmental conditions, method of cultivation and maturity. Our results from a row-harvested crop during two consecutive years suggest that different irrigation and mycorrhizal treatments affect important nutritional characteristics, such as SSC and lycopene content, which are detectable in the VIS-NIR range. Above 560 nm, reflectance values became higher; the maximum reflectance was measured between 645 and 713 nm, depending on the sample. Treatments could be discriminated by different average values of reflectance spectra. After assessment of the spectral results and laboratory data calibration models, the first derivative of the spectra proved to be the best for each calibration model. Experiments suggest that different irrigation regimes and mycorrhizal treatments affect important nutritional characteristics such as the lycopene and SSC.