Authentication of apples (Malus × domestica borkh.) according to geographical origin, variety and production method using 1H NMR spectroscopy and random forest
Soeren Wenck, René Bachmann, Sarah‐Marie Barmbold, Anna Lena Horns, Nele Paasch, Stephan Seifert
Abstract
When buying apples, there are several characteristics that are important to the consumer. These include taxonomic variety, which influences the desired flavor and the allergenicity, and, increasingly, whether the cultivation is regional and organic. In this study, we analyzed 217 apple samples with 1 H NMR spectroscopy and verified the authentication of the apples in terms of country of origin, local origin within Germany, taxonomic variety and whether they were organically produced. The obtained random forest models showed classification accuracies ranging from about 73 % for the discrimination of seven taxonomic varieties to 88.5 % for the separation of German and non-German samples. The results demonstrate that 1 H NMR spectroscopy is promising for comprehensive authentication of apples. This is achieved by using different parts of the NMR fingerprint depending on the desired outcome, which was confirmed by the application of variable selection methods and the comparison of the selected variables. • 217 apple samples were analyzed with 1 H NMR spectroscopy. • NMR signals were assigned to known apple metabolites. • Random forest was applied for the differentiation of apples according to five different authentication issues. • Relevant signals were selected by random forest variable selection. • Exclusive spectral regions for each authentication issue could be identified.