Based on HS-SPME-GC-MS combined with GC-O-MS to analyze the changes of aroma compounds in the aging process of Citri Reticulatae Pericarpium

Abstract

Citri Reticulatae Pericarpium (CRP) is a very well-known foodstuff. It can not only be drunk directly like tea, but also be used as a condiment for cooking food. This study used headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), gas chromatography-olfactometry-mass spectrometry (GC-O-MS), and sensory evaluation to analyze and evaluate CRP over the six-year aging process (2, 5, 10, 15, 20, and 25 years). HS-SPME-GC-MS identified 93 volatile components, while GC-O-MS detected 42 aroma compounds. The results indicated that the aroma intensity (AI) of the spicy, woody, and herbal aroma compounds remained unchanged, while those with citrus and fruity notes gradually decreased and even disappeared with extended storage time, which could explain the unique CRP aroma. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed that the CRP in the six-year aging process was clearly divided into three groups: young-aged samples (2Y), middle-aged samples (5Y and 10Y), and old-aged samples (15Y, 20Y, and 25Y). In addition, combining sensory evaluation and GC-O-MS fully reflected the changes during the different CRP aging stages. This study confirmed the potential of combining GC-O-MS and OPLS-DA as a reliable analytical selection technique to distinguish CRP age. Finally, 13 key aroma compounds were screened using VIP >1 and p < 0.05, including isopulegol, dodecanal, and α-calacorene.