Physicochemical, antioxidant and antimicrobial activities of green teas manufactured from common tea clones of different gardens in Bangladesh

Abstract

Green tea's health-promoting actions are mostly due to its phytochemical content and antioxidant property. Due to the toxicity and cancer-causing properties, synthetic antioxidants are injurious to human health. Therefore, natural products such as teas might be chosen as antioxidants and antibacterial agents instead of synthetic ones. This investigation was performed to analyze the phytochemical constituents, antioxidant and antibacterial characteristics of green teas produced from some commonly cultivated tea clones of different gardens in Bangladesh. pH, total soluble solids, vitamin B (B1, B2) and C, caffeine and tannin of green teas were estimated for the quantification of phytochemicals. DPPH free radical scavenging, total phenolic content, and total flavonoid content were quantified to determine antioxidant activity. Gram-positive Bacillus spp. and Gram-negative Escherichia coli were used for antibacterial activity. BT2 revealed the greatest level of caffeine and tannin content of 2.033 and 4.846 g/100g sample respectively. TV9 showed the highest amount of vitamin B1, B2, and C which was 1450.02, 2707.12, and 2983.04 mg/100g sample respectively. TV9 also exhibited the highest antioxidant capacity of 78.23%, the highest amount of phenolics (2.25 g GAE/100g sample), and the highest levels of flavonoids (918.27 mg QE/100g sample). In the case of antimicrobial activity, TV9 exhibited the highest zone of inhibition (ZOI) of 15.61 mm against Escherichia coli which was moderately susceptible. BT2 showed the highest ZOI of 17.35 mm against Bacillus spp. which was susceptible. These tea extracts can be employed in the medicine and food sector as an alternative to synthetic antioxidants and antibacterial agents.

Keywords

• Green tea
• Physicochemical properties
• Antioxidant activity
• Antimicrobial activity
• Disc diffusion method