Fig 1. PCA results on mid-infrared spectral data of apple skin and pulp. A: spectral area between 1500–1000 cm^-1, B: spectral area between 2000–1500 cm^-1 and C: spectral area between 3000–2500 cm^-1.

The code corresponds to the cultivar (M: Melrose, S: Smoothee, A: Ariane), to the management system (C: conventional, O: organic, L: low-input) and to the year 2011, 2012 and 2013.