Qualitative gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry fingerprinting of tissue-specific phytochemicals in finnish Quercus robur L. acorns

Acorns of Quercus robur L. are abundant in Finland but remain underutilized, and their chemical composition in high-latitude regions is not well documented. In this study, Finnish acorns were analyzed using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-high resolution mass spectrometry (LC-HRMS) to provide a qualitative overview of their nonpolar and polar compounds. We examined fresh whole acorns as well as dried acorn nuts and dried pericarp fractions. GC-MS analysis indicated that fresh whole acorns were characterized by signals corresponding to phytosterols and tocopherol-related compounds, whereas dried acorn nuts presented increased relative abundances of long-chain n-alkanes. Similarly, dried pericarp analysis showed sterol-related signals and long-chain aldehydes. LC-MS analysis suggested that polar fractions were characterized by ellagitannins, phenolic acids, flavonoids, and organic acids. Although the study is qualitative, it provides the first combined GC-MS and LC-MS fingerprint of the chemical profiles of Finnish Quercus robur L. acorns. Hence, our results provide a foundation for future quantitative studies and application-oriented research on acorn valorization.