Rapid screening of phenolic compounds in congou black tea ( Camellia sinensis ) during in vitro fermentation process using portable spectral analytical system coupled chemometrics

Black tea composite contains a wide range of simple and complex phenolic compounds known for their antioxidant capabilities. Herein, a portable near-infrared (NIR) spectroscopy (899–1724 nm) was used to predict the concentrations of cianidanol, ferulic acid, gallic acid, L-epicatechin, phloridzin and rutin in congou black tea. High-performance liquid chromatography-diode array detector (HPLC-DAD) was also utilized as a reference method. Models were predicted and constructed based on the data acquisition from portable NIR and HPLC-DAD using partial least squares (PLS) followed by variables selection algorithms such as competitive adaptive reweighted sampling-PLS and ant colony optimization-PLS. The correlation coefficient of calibration (RC) and correlation coefficient of prediction (Rp) was found in ranged from 0.785 to 0.979 and 0.751 to 0.969, respectively. The overall results indicates portable NIR combined successfully with multivariate chemometrics offers a non-destructive technique for the rapid screening of the phenolic compounds of congou black tea. Practical applications Phenolic compounds play a significant role or as a key indicator of black tea quality. To the best of our knowledge, this is the first study for monitoring these compounds during black tea fermentation. Current study reported a first time non-invasive and non-destructive method for determining the quality index of black tea with reasonable accuracy and that could be endorsed a model approach as it addresses more advantages over conventional methods. This study successfully predicted phenolic compounds in black tea during fermentation after using a portable near-infrared spectroscopy coupled multivariate chemometrics. Furthermore, current work encourages fast, nondestructive quantification of various analyte in food and biological engineering as a quality and safety indicator.