Overall control of the quality consistency of Citri Retriculatae Pericapium by combining HPLC fingerprint, terahertz time-domain spectroscopy and chemometrics

Citri Retriculatae Pericapium (CRP), a citrus waste, has antioxidant, anti-inflammatory, and anti-cancer properties and can be utilized as a functional food, but its origin and vintage have a significant impact on its quality. For this reason, in this paper, distinct types, origins, and storage times of CRP were classified and identified using partial least squares discriminant analysis (PLS-DA), terahertz fingerprinting, HPLC fingerprinting, and the quantified ratio fingerprint method (QRFM). Based on the PLS-DA, it was essentially determined that origin > storage period > variety was the order of influence of substance content on CRP, and the QRFM could also successfully achieve the classification. In order to preserve fingerprint information while streamlining the data, four spectroscopic quantum procedures were described, their similarities and differences were analyzed, and they were applied to terahertz spectroscopy fingerprints. Finally, it was discovered that the correlation between the average percentage of fingerprint peak area (PA) and the average percentage of the content (P(C)), which was established, had the potential to represent the overall information of the fingerprint profile when quantifying five components as opposed to three quantitative components (P(5C) was able to establish linear relationships with PA((HPLC)) and PA((THz-TDs)), with Pearson correlation coefficients of 0.8955 and 0.9416, respectively). This offered a new concept for locating Q-markers. This research advanced the establishment of quality control for complicated samples and offered new approaches for fingerprinting food products like CRP.