Volatile profiles of 47 monovarietal cloudy apple juices from commercial, old, red-fleshed and scab-resistant apple cultivars

This study provides cultivar-specific metabolic fingerprints of volatile organic compounds in the headspace of cloudy apple juices. Cloudy juices from 47 true to type apple cultivars grown under identical agricultural and climatic conditions in South Tyrol, Italy, have been analysed through headspace solid-phase microextraction gas chromatography coupled with high-resolution time-of-flight mass spectrometry (HS-SPME/GC-HRTOF-MS), yielding cultivar-specific volatile organic compound (VOC) profiles. Apple cultivars included 10 old cultivars with local relevance, 18 commercial cultivars, dominating the current international market, 10 scab-resistant and 9 red-fleshed ones. The 28 most abundant VOCs were found in the whole dataset, indicating a remarkable chemodiversity within juices. The main discriminant metabolites were butyl acetate; pentyl acetate; 2-methylbutyl acetate; pentan-1-ol; hexan-1-ol; n-hexanal and (E)-2-hexenal. A principal component analysis (PCA) and a hierarchical cluster analysis (HCA) have not identified a clear separation of the analysed cultivar classes. Nevertheless, a series of scab-resistant and red-fleshed cultivars with VOC profiles similar to established commercial cultivars were identified; these data could help substituting current cultivars with more sustainable ones. On a more general basis, our study supports a knowledge-driven selection of apple cultivars for specific consumer preferences and helps appreciating the biodiversity of apples across old local and more recent (scab-resistant and red-fleshed) cultivars.

Automated summary

This study identified cultivar-specific metabolic fingerprints of volatile organic compounds in cloudy apple juices from 47 true-to-type apple cultivars in South Tyrol, Italy. Despite the lack of clear separation of cultivar classes in principal component analysis and hierarchical cluster analysis, certain scab-resistant and red-fleshed cultivars with VOC profiles similar to established commercial cultivars were identified, suggesting potential for substituting current cultivars with more sustainable ones. The study supports a knowledge-driven selection of apple cultivars for specific consumer preferences and highlights the biodiversity of apples across old local and more recent cultivars.