Chemometric characterization of 30 commercial thermal and cold processed juices using UPLC-QTOF-HR-MS fingerprints

The present study investigated the phenolic fingerprinting of untargeted metabolites using UPLC-QTOF-MS combined with chemometrics to identify potential metabolites in 30 commercial juices belongs to thermal and cold processed juices. A total of 47 compounds were tentatively identified using high resolution mass spectra. Kaempferol and quercetin glycosides were found in higher abundance in cold processed kale and melon juices respectivley whereas decarboxylated betalains were found to be high in thermal processed beet juices. The HPLC results shows the significant variation of ascorbic acid (2.6 +/- 0.1 to 661 +/- 9 mu g/mL) and total ascorbic acid (4.6 +/- 0.0 to 1183 +/- 96 mu g/mL) in tested juice samples, whereas pure beet juice had the highest nitrate content (1075 +/- 9 mu g/mL). The food ingredients and processing technique massively affected the antioxidant capacity. For instance, thermal processed kale, beet, and melon juices exhibited higher total phenolics and antioxidant capacity than the cold-pressed juices. Moreover, organic beet and organic melon juice samples showed relatively higher phenolics and antioxidant capacity kale samples. The results demonstrated that chemometrics is an efficient tool for discriminating thermally and cold-pressed commercial juices.