Chemometrically-supported quality assessment of chamomile tea

The quality of chamomile (Matricaria recutita) is largely determined by its content of essential oils and flavonoids, the main pharmacologically active constituents. In this study, the phyto-chemical profiling of 22 commercially available chamomile flower tea samples was aided by chemometrics, comparing loose teas of whole heads with tea bags containing comminuted flowers. Principal component analysis (PCA) and agglomerative hierarchical clustering (AHC), which included both essential oil and flavonoid constituents, showed that chamomile teas can be well-differentiated and categorised into two groups that are closely related to the pharmaceutical form and largely explain the influence of processing. Multivariate analyses of the phytochemical data matrix showed clear differences between loose chamomile tea and tea bags, with the former having a more consistent composition and an overall higher quality. The essential oil content varied widely (0.75-5.34 mL kg^-1), with only five loose teas exceeding the minimum content specified in the European Pharmacopoeia (≥ 4 mL kg^-1), while most tea bag samples did not fulfil this requirement. GC-MS analyses of essential oils revealed sesquiterpenes as predominant constituents, assigning all samples to the bisabolol oxide-rich chemotype. The total flavonoid content determined by UV/Vis spectrophotometry ranged from 0.17 to 0.55 %, whereas RP-HPLC/DAD analysis revealed that the levels of apigenin-7-glucoside in tea bag samples often did not meet pharmacopoeial standards. Partial least squares-discriminant analysis (PLS-DA) yielded a robust and statistically significant model, showing for the first time that the quality differences between loose teas and tea bags can be explained by at least four key components. These results highlight the utility of chemometric tools in chamomile quality assessment and emphasise the need for improved standardisation that supports the preference for whole flower teas to ensure therapeutic efficacy.