NMR Characterization of Ten Apple Cultivars from the Piedmont Region

Abstract

The metabolite profile of ten traditional apple cultivars grown in the Piedmont region (Italy) was studied by means of nuclear magnetic resonance spectroscopy, identifying an overall number of 36 compounds. A more complete assignment of the proton nuclear magnetic resonance (1H NMR) resonances from hydroalcoholic and organic apple extracts with respect to literature data was reported, identifying fructose tautomeric forms, galacturonic acid, γ-aminobutyric acid (GABA), p-coumaroyl moiety, phosphatidylcholine, and digalactosyldiacylglycerol. The chemical profile of each apple cultivar was defined by thorough quantitative NMR analysis of four sugars (fructose, glucose, sucrose, and xylose), nine organic acids (acetic, citric, formic, citramalic, lactic, malic, quinic, and galacturonic acids), six amino acids (alanine, asparagine, aspartate, GABA, isoleucine, and valine), rhamnitol, p-coumaroyl derivative, phloretin/phloridzin and choline, as well as β-sitosterol, fatty acid chains, phosphatidylcholine, and digalactosyldiacylglycerol. Finally, the application of PCA analysis allowed us to highlight possible differences/similarities. The Magnana cultivar showed the highest content of sugars, GABA, valine, isoleucine, and alanine. The Runsé cultivar was characterized by high amounts of organic acids, whereas the Gamba Fina cultivar showed a high content of chlorogenic acid. A significant amount of quinic acid was detected in the Carla cultivar. The knowledge of apple chemical profiles can be useful for industries interested in specific compounds for obtaining ingredients of food supplements and functional foods and for promoting apple valorization and preservation.

Analysis of Fatty Acids, Amino Acids and Volatile Profile of Apple By-Products by Gas Chromatography-Mass Spectrometry

“…The cultivation conditions and techniques, species, and variety have a significant impact on the chemical composition of apples [ 3 ]. The quality of apples is related also to their fatty acids and free amino acids content [ 41 ].…”

“…Apples ( Malus domestica Borkh. ), a member of the Rosaceae family, represent one of the most consumed fruits with a worldwide production of 86.1 million tons per year in 2018 [ 1 ] occupying third place after bananas and watermelon production [ 2 , 3 ].…”

“…They are consumed as fresh fruits or can be used for apple juice, jam, cider, and vinegar manufacture generating high amounts of residue, entitled apple pomace [ 4 ]. Apples are considered low-calorie fruits, extremely rich in vitamins, dietary fiber, minerals, phenols, and acids, and are able to prevent some diseases such as cancer, cardiovascular disease, or asthma [ 3 ]. Moreover, apple phenolic compounds and triterpene acids exhibit anti-inflammatory properties and have shown protective effects against Alzheimer’s disease [ 5 ].…”

“…A substantial amount of literature describes the AP bioactive molecules such as polysaccharides, polyphenols, vitamins, dietary fiber, and minerals [ 3 , 4 , 5 , 10 , 14 , 15 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ], but as far as we know, there is a lack of knowledge regarding its content in fatty acids, amino acids, and especially, aroma volatile compounds. Analytical techniques such as HPLC (high-performance liquid chromatography), HS-SPME (headspace solid-phase microextraction) coupled with GC-MS (gas chromatography-mass spectrometry), GC-MS, and HS–SPME/GC–qMS (headspace–solid-phase microextraction gas chromatography combined with quadrupole mass spectrometry) were used by a large body of literature for the identification and quantification of amino acids and aroma volatile compounds, respectively [ 30 , 31 , 32 , 33 ].…”

Metabolomic Profiling of Fresh Goji (Lycium barbarum L.) Berries from Two Cultivars Grown in Central Italy: A Multi-Methodological Approach

“…This is due to the combined interpretation of both one-dimensional and two-dimensional NMR experiments. The 1 H NMR spectral assignments of hydroalcoholic ( Table 1 ) and organic ( Table 2 ) Bligh-Dyer extracts were carried out by means of 2D experiments and literature data regarding other vegetable matrices analyzed in the same experimental conditions [ 21 , 22 ]. Three sugars, six organic acids, fifteen amino acids, choline, and trigonelline were detected in all the hydroalcoholic Bligh-Dyer extracts and their characteristic 1 H NMR signals were used for compound quantification.…”