Untargeted NMR Spectroscopic Analysis of the Metabolic Variety of New Apple Cultivars

Abstract

Metabolome analyses by NMR spectroscopy can be used in quality control by generating unique fingerprints of different species. Hundreds of components and their variation between different samples can be analyzed in a few minutes/hours with high accuracy and low cost of sample preparation. Here, apple peel and pulp extracts of a variety of apple cultivars were studied to assess their suitability to discriminate between the different varieties. The cultivars comprised mainly newly bred varieties or ones that were brought onto the market in recent years. Multivariate analyses of peel and pulp extracts were able to unambiguously identify all cultivars, with peel extracts showing a higher discriminative power. The latter was increased if the highly concentrated sugar metabolites were omitted from the analysis. Whereas sugar concentrations lay within a narrow range, polyphenols, discussed as potential health promoting substances, and acids varied remarkably between the cultivars.

Detailed Structural Characterization of Arabinans and Galactans of 14 Apple Cultivars Before and After Cold Storage

“…However, only eight cultivars were usable after storage ( Table 1 ). Further details about characteristics, harvesting, and storage of the apple samples were described previously ( Eisenmann et al, 2016 ). Apples were peeled, and the pulp without seeds and apple-core was freeze-dried.…”

NMR Characterization of Ten Apple Cultivars from the Piedmont Region

“…The 1 H and 13 C NMR spectra assignments apple aqueous ( Figure 2 ) and organic ( Figure 3 ) extracts of apple were carried out using 2D NMR experiments, standard compound addition, and literature data [ 24 , 25 , 26 , 37 ]. A more complete spectral assignment ( Table 2 ) of the aqueous extracts with respect to literature data was obtained, identifying fructose tautomeric forms, galacturonic acid, GABA, and p -coumaroyl moiety.…”

“…Apple chemical composition has been largely investigated using targeted chromatographic techniques, such as high-performance liquid chromatography (HPLC) to determine phenolic content [ 13 , 14 , 15 , 16 ] and gas chromatography (GC) for the determination of sugars, polyols, sugar phosphates, organic acids, sterols, polyphenols [ 17 ], fatty acids [ 18 ], and other aromatic compounds [ 19 , 20 ]. Untargeted proton nuclear magnetic resonance ( 1 H NMR) methodologies [ 21 ] have focused mainly on apple juice matrixes [ 19 , 22 , 23 ] to study the chemical composition of new cultivars [ 24 ], cultivars with different resistances against fungi attacks [ 25 ], and commercial cultivars from Japan and New Zealand [ 26 ]. 1 H high field NMR spectroscopy has already shown to be a valuable tool to investigate local typical products, such as red sweet peppers [ 27 ], white celery [ 28 ], tomatoes [ 29 ], and olive oils [ 30 ].…”

Integrating genomics and multi-platform metabolomics enables metabolite QTL detection in breeding-relevant apple germplasm

“…Fig. S8), indicating that they represent compounds that contain aromatic hydrogens, likely phenolics and aromatic amino acids (Eisenmann et al 2016;Iaccarino et al 2019).…”