Apples ripening stage and nutraceutic properties evaluation through a Vis-NIR portable device and an on-line NIR system.

Apples production, with 60 millions of tons processed in a year, has a very important role for the world produce market. Non-destructive and rapid tools in fruit production are required for predicting the optimum harvest window and for monitoring fruit quality during postharvest period. At the present the evaluation of nutraceutic compounds has also become interesting because the main function of this kind of molecules in the prevention of degenerative diseases and their role in quality preservation of fruits during storage, due to their antioxidant properties. With this aim, an optical, portable, experimental device (Vis-NIR spectrophotometer) for single sample, non-destructive and quick prediction of the ripening time period and sensorial properties of the fruits (chlorophyll, soluble solids content and fruit firmness) in the wavelength range 450-980 nm was built and tested. This device was also used for the evaluation of nutraceutic compounds like polyphenols, flavonoids, carotenoids and ascorbic acid. At the same time an automatic on-line NIR system (QS-online, Unitec®) was tested to predict fruit quality directly on a processing line in the wavelength range 800-1200 nm. Regression models were built on the samples of two apple varieties (Golden Delicious e Stark Red Delicious). PLS models based on spectral data of portable Vis-NIR device show, for both varieties, good prediction skills for soluble solids content, carotenoids, chlorophyll and titrable acidity. The results of the on-line NIR system, regarding the classical parameters, supplied fair PLS models for both soluble solids content and firmness. These data show system’s effectiveness for quick evaluation of fruits quality.