DIFFERENTIATION OF BRAZIL TEA COMPOSITION BASED ON FERMENTATION TIME USING AN IMPEDIMETRIC ELECTRONIC TONGUE AND CHEMOMETRICS

Tea (Camellia sinensis) is an aromatic beverage known for its therapeutical properties, providing numerous health benefits to the consumer. The traditional black tea production process involves four stages: plucking, withering, fermentation, and firing. Numerous factors influence final tea quality; one among them is the fermentation time. Fermentation causes biochemical changes in the tea leaves, i.e., converts catechins to theaflavins and thearubigins. Optimal fermentation time is essential to produce the changes in the leaves that influence the final tea quality. The objective of this study is to differentiate black tea composition based on their fermentation time using an impedimetric electronic tongue. The multi-sensor system (e-tongue) can analyze liquid samples and is advantageous over traditional analyses, which require expensive chemicals and instruments. Data from the e-tongue will be processed using Principal component analysis (PCA), an exploratory tool that works by reducing dimensions to identify uncorrelated variables. Reference analysis, including total polyphenols (TPC), total flavonoids (TFC), and caffeine content (CC), was carried out to examine the discrimination seen in the PCA score for the three classes of samples: A, B, and C, which are divided based on their fermentation time 6,7 and 8 hours respectively. The results showed that both scores of PC1 and PC2 were able to discriminate the three classes of samples. The statistical data analysis using ANOVA shows the total polyphenols had major differences between the classes, with a minor and no possible difference between classes were noted for total flavonoids and caffeine, respectively. Indicating the possible variations in PCA could be bought by TPC and TFC values, plotting a PCA for electronic tongue data according to varying concentration ranges of the reference values helped us confirm the same. Class B produced tea with higher total flavonoid content among the three classes, which can be desirable. Class C had lower chemical composition than its counterpart and could discriminate using the electronic tongue. This helps us identify that up to 8 hours of fermentation is not ideal for black tea production as it reduces the important chemical constituents responsible for the final tea quality. Despite the closeness in reference values for classes A and B, the electronic tongue detected this minor difference which was visualised using the PCA scores. Concluding, the electronic tongue is feasible to classify three classes of black tea composition based on their fermentation time, supporting future works for the application of impedimetric e-tongue as an effective tool for monitoring black tea processing.