Polyphenolic characterisation of old local apple varieties from Southeastern European region

• Phenolic content of old apples is higher than that of commercial apples.
• Proanthocyanidins were the dominant phenolic compounds.
• Slavonska srčika variety was found to be the richest in phenolics.
• Ljubeničarka variety has an attractive red coloured flesh containing anthocyanins.
• Some old local apple varieties could be important in future breeding programs.

Ancient apple cultivars grown in local areas have so far been largely unexplored and might represent an important source of polyphenols. In this work, the phenolic profile in the flesh and peel of thirteen old apple varieties from the Balkan region was studied by liquid chromatography with ultraviolet–visible diode array detector and mass spectrometry detectors (ion trap, quadrupole time-of-flight); 26 compounds were identified. Proanthocyanidins were detected as dimers to heptamers and they were further analysed after acid-catalysis in the presence of phloroglucinol (degree of polymerisation 3.8–10.3). Epicatechin represented more than 85% of constitutive units. Proanthocyanidins were the major class of polyphenols in flesh and peel (>70% of total polyphenols), phenolic acids were mainly distributed in the flesh (6–25%); flavonols (1–13%) and dihydrochalcones (1–10%) in the peel, and anthocyanins (1–7%) in the peel of red coloured apples. “Ljubeničarka” showed unique red-coloured flesh (unusual for apples) due to the presence of anthocyanins in the flesh. Old apple varieties are rich in phenolic compounds, in quantities even higher than those found in commercial varieties, and might constitute the basis for further breeding.