Pressurized Liquid Extraction of Antioxidant Compounds from Green Tea
Background and Objective: India is the second largest producer of green tea. The green tea is a major source of health promoting antioxidant group (catechins). The main aim of the present study was to extract green tea antioxidant rich extract by using pressurized extraction technique for antioxidant study. Materials and Methods: Four varieties of green tea were extracted by using pressurized liquid extraction (PLE) method using ethanol as the solvent. In order to get maximum yield of biologically active compounds, extraction conditions were optimized in terms of pressure, temperature and solvent flow rate. Results of total phenol, flavonoids and antioxidant extraction were analyzed statistically by using one way ANOVA with Tukeys B-test. Results: The optimum pressure for recovering maximum phenolic acids and major catechins was found to be about 150 bar. Out of seven investigated phenolic acids and five catechins, vanillin followed by gallic acid, catechin and epigallo catechin gallate were found to be in major concentrations. Total phenol content of all four varieties was found to be more than total flavonoid content. Darjileeng variety gave best results for total phenol content (607.03 mg GAE gG1 dry weight basis) and percent DPPH inhibition (74.40%) while Assam and Nilgiri variety gave best results for total flavonoid content (79.15 mg QE gG1 dry weight basis) and percent ABTS inhibition (51.34%). Antimicrobial activity (bacterial and fungal) of extracts from all four varieties was screened through well diffusion method in order to study their inhibitory effect. Bacterial strains were found to be more sensitive than fungal strains. Conclusion: The PLE could be the promising method for extraction of antioxidant compounds (phenolic and flavonoids) from green tea.