Differentiation of commercial apple juices based on multivariate analysis of their polyphenolic profiles

The concentration of individual phenolic acids and flavonoids was determined in differently processed com-mercial apple juices (n = 54) from various product categories, including juices reconstituted from concentrate (FC), both clear and cloudy varieties, as well as not from concentrate (NFC) juices, both fresh and pasteurized products, by means of high-performance liquid chromatography. The studied apple juices were a miscellaneous source of polyphenolics and chlorogenic acid was found to be the dominant polyphenolic compound with a concentration ranging from 29.6 mg L-1 found in fresh juice to 406.8 mg L-1 in pasteurized NFC juice, followed by flavan-3-ols. Pattern recognition techniques including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to explore and classify juices according to polyphenolic profiles. PLS-DA showed satisfactory discrimination between FC and NFC apple juices, the calibration and prediction error rates were 8 % and 12 %, respectively. Based on the variable importance in projection (VIP) and selectivity ratio (SR), individual polyphenolic compounds that contribute significantly to the discrimination of juices were identified. HPLC coupled with pattern recognition methods was found to be a promising tool for grouping commercially available apple juices based on their polyphenolic profile.

Automated summary

The concentrations of phenolic acids and flavonoids were measured in different types of commercial apple juices using high-performance liquid chromatography. Chlorogenic acid was the dominant polyphenolic compound, followed by flavan-3-ols. Pattern recognition techniques were used to classify the juices based on their polyphenolic profiles, with satisfactory discrimination between juices made from concentrate and not from concentrate. HPLC combined with pattern recognition methods is a promising tool for grouping commercially available apple juices based on their polyphenolic profile.