Principal component analysis of metabolomics data from extracts of (A) apple fruit peel (harvest 2008), (B) apple fruit peel (harvest 2003), (C) apple fruit flesh (harvest 2008), and (D) apple fruit flesh (harvest 2003). PC, principal component. Symbols are used to indicate loadings for different apple cultivars: ‘Golden Delicious’, yellow squares; ‘Gala’, light blue triangles; ‘Red Delicious’, red diamonds; ‘Fuji’, dark blue triangles; ‘Granny Smith’, green circles; ‘Cox’s Orange Pippin’, orange pentagons.