# Hyperspectral Imaging as a Rapid Quality Control Method for Herbal Tea Blends
## 3 Results and Discussion
### Rooibos and Buchu Blend
The results compared well to the company formulation (97:3; rooibos:buchu) provided to assess the accuracy of HSI as a quality control method for the blend. The lowest proportion recorded for rooibos in a blend was 94.5% and a highest was 98.5%. For buchu, a lowest proportion value of 1.47% and highest value of 4.98% was recorded. The results demonstrate the accuracy of HSI with minimal deviation from the production ratios. Figure 1: (**a**) Hyperspectral red, green, blue (RGB) image of rooibos and buchu raw materials prior to multivariate analysis; (**b**) Principal component analysis (PCA) score image of t2 demonstrating distinct color amplitudes for the two teas and (**c**) score scatter plot (t2 vs. t3) illustrating two distinct pixel clusters colored according to score values corresponding to the two teas. Figure 2: (**a**) Partial least squares-discriminant analysis **Y**-image showing classification of the raw materials in the calibration set and (**b**) the prediction set showing the proportion of raw constituents colored according to the predicted class. \begin{table}
\begin{tabular}{l l c c c c c c c c c c c c c c c c c c c c c c c c} \hline \multicolumn{1}{c}{**Tas Bag Blend**} & \multicolumn{1}{c}{ \begin{tabular}{c} Raw Material \\ **Consitiments** \\ \end{tabular}  } & \multicolumn{1}{c}{ \begin{tabular}{c} **Company** \\ **Formalization (Cs)** \\ \end{tabular}  } & \multicolumn{1}{c}{ \begin{tabular}{c} **Ave** \\ **dev** \\ \end{tabular}  } & \multicolumn{1}{c}{\ \begin{tabular}{c} **Sd** \\ **dev** \\ \end{tabular}  } & \multicolumn{1}{c}{ \begin{tabular}{c} **Hyprespeeted Imaging Percentage Pixel Abundance in **Tos Bag Tc** **Berg** \\ \end{tabular}  } \\ \cline{3-19}  
The UHPLC-MS method was used to qualitatively validate the results obtained using HSI by confirming the presence of the raw material marker molecules in the tea bag blends. The chromatographic profiles of rooibos, buchu and the tea bag blend and the results are presented in Figure 3. The marker compound for rooibos, aspalathin, was used to confirm that the raw material was rooibos (Figure 3a) and also to confirm the presence of rooibos in the tea bag blend (Figure 3c). Both rooibos raw material and the corresponding tea blend analyzed in the positive ion mode demonstrated similar chromatographic profiles, showing the presence of aspalathin at a retention time (_Rt_) of 5.43 min, as the major compound. A similar approach was used to confirm the identity of buchu raw material and the presence of buchu in the tea bag blend. Rutin (_Rt_ = 5.56 min) and hesperidin (_Rt_ = 7.99 min) which are marker molecules in buchu, were identified in the raw material (Figure 3b) and in the corresponding tea bag blend (Figure 3c). The results demonstrate that both HSI and UHPLC-MS were able to confirm the presence of the raw material constituents in tea bag blends. Figure 3: (**a**) Ultra-high performance liquid chromatography mass spectroscopy (UHPLC-MS)-ES\({}^{+}\) chromatograms showing the marker compound aspalathin (_Rt_ = 5.43 min) identified in rooibos and (**b**) marker compound rutin (_Rt_ = 5.56 min) and hesperidin (_Rt_ = 7.99 min) in buchu and (**c**) markers compounds rutin and hesperidin and aspalathin in the tea bag blend. _Rt_: retention time