Food Authenticity Analyses of Apple Juice Concentrates by UPLC‐IMS‐QTOF Mass Spectrometry and NMR Techniques

Abstract

Product authenticity of is an integral part of consumer protection in the food industry. With regard to fruit juices, the most common adulterations are based on mislabeling of the product in terms of its quality, geographical or botanical origin. Other relevant quality checkpoints are the non-declared addition of materials like e.g. water, sugars, acids or other juice qualities and materials. Since apple juice is the second most produced juice in the world, authenticity analyses are of particular importance, especially due to large price differences depending on its geographical origin. [1, 2] Juice-to-juice debasing, the addition of cheaper juices, is of great economic relevance and represents another important topic for apple and pear juicesdue to similarities in their major polyphenolic composition. This issue can be clarified by the evaluation of the presence of fingerprint markers using metabolic profiling. [3] In recent decades, many studies focused on juice authenticity analyses by LC/MS and NMR techniques. Both methods have become important tools for metabolic fingerprinting. In our studies, it is shown for the first time, that an addition of pear juice concentrate to apple juice can already be detected with a content of less than 10 % due to the marker substance arbutin by UPLC-QTOF mass spectrometry coupled with ion mobility spectrometry (IMS) without any additional clean-up steps. The IMS allows accurate measurements of the rotationally-averaged collision cross-section (CCS) of ions in the gas phase, which is related to their chemical structure and threedimensional conformation. Therefore, the combination of UPLC-QTOF mass spectrometry with IMS provides an increased confidence in marker substance identification of complex matrices compared to traditional LC/MS approaches.In contrast to this kind of targeted analysis, 1 H-NMR profiling offers capabilities for nontargeted analysis for fraud detection, making it powerful screening tool for adulteration.[4] PCA-and PLS-related approaches as well as neural networks can provide correlations between spectral features and the products geographical origin. Combining the strengths of both approaches, UPLC-IMS-QTOF and NMR, results in a great improvement in authenticity analysis of Apple Juice Concentrates.