Antibacterial Activity of Green Tea Leaf Extract Against Dairy-Associated Bacteria and Its Application in Pasteurized Milk

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Bacterial contamination in pasteurized milk remains a potential cause of milk-borne diseases. Pasteurization may not eliminate all bacteria, thereby posing health risks. This study evaluated the potential of green tea leaf extract as an antibacterial agent to enhance pasteurization treatment by reducing contaminant bacteria and assessing its effect on milk flavor after treatment. Green tea leaves were extracted using the decoction technique. Antibacterial activity was evaluated using the agar well diffusion method, and bacterial reduction after pasteurization was measured using the total plate count (TPC) test. Panelist acceptance was assessed organoleptically based on color, aroma, and taste. The results showed that green tea leaf extract at a concentration of 5% had a very strong inhibitory effect (≥ 20 mm) against Staphylococcus aureus ATCC 25923 and Staphylococcus aureus SM 3.2.3, reducing bacterial counts by 5.2 log CFU ml-1. Organoleptic testing of pasteurized milk treated with 1 to 5% extract showed consistently favorable scores for color, aroma, and taste. These findings indicate that green tea leaf extract has considerable potential to reduce S. aureus contamination and enhance the effectiveness of pasteurization for commercial application.