Abstract
In the past 2 years, the suitability of NIR-(near infrared-)spectroscopy for the non-destructive quality assessment of apples was investigated. The measuring system (Sacmi F5, Imola, Italy) is based on spectral analysis of NIR transmittance which is more accurate than the reflectance modus. It is equipped with a mechanical setup for commercial sorting-lines. The entire fruit is illuminated by an intensive halogen light source. The spectral changes of transmitted light contain information about chemical and physical composition, ripening and internal disorders of the respective fruit. The aim of the study was to compare this newly developed instrument with traditional destructive techniques. In order to optimize the reliability of NIR-measurements, specific calibration models for each apple cultivars were created. The cultivars under study were 'Gala', 'Golden Delicious', 'Red Delicious', 'Jonagold', 'Braeburn', 'Granny Smith', 'Fuji' and 'Cripps Pink'. The non-destructive detection of quality parameters (i.e. total soluble solids, firmness and internal flesh browning) of apples of a wide range of maturity stages was evaluated. In order to be able to compare the two different analytical methods, particular attention was laid upon the development of an appropriate statistical procedure. Thus, information regarding reliability and reproducibility of the two techniques was obtained by calculating intraclass correlation coefficients in addition to conventional values like the correlation factor and the standard error of prediction. Moreover, a graphic representation of the statistical comparison is given.