T/GZTPA 0005-2020 Active

Scope: This standard specifies the requirements for the determination of moisture content, water-extractable substances, total ash, catechins, total free amino acids, caffeine, gallic acid (GA), epigallocatechin (+C), epicatechin (EC), epigallocatechin gallate (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) in Guizhou green tea by near-infrared diffuse reflectance spectroscopy. This standard is applicable to the rapid and simultaneous determination of the main chemical components in Guizhou green tea in the near-infrared spectral region (12,800 cm-1 to 4,000 cm-1 or 780 nm to 2,500 nm). This standard is suitable for the rapid determination of the main chemical components in Guizhou green tea, but not for arbitration testing. Main technical content: There is a correlation between the changes in the content of sample components and their corresponding near-infrared spectral changes. The near-infrared diffuse reflectance spectra of a calibration sample set are obtained by using the diffuse reflection method, and an appropriate chemometric calibration method is selected to correlate the near-infrared spectra of the calibration sample set with their corresponding main chemical component contents, thereby establishing a calibration model. The validity of the calibration model is verified using a validation sample set. The main chemical component contents of the sample to be tested are calculated using the calibration model that has passed the application verification and the near-infrared diffuse reflectance spectra of the sample to be tested.