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Influence of temperature and brewing time on the total polyphenol content in tea

Skrodzka Barbara, Kolmaga Agnieszka, Oszajca Katarzyna, Gawron-Skarbek Anna

Postępy Techniki Przetwórstwa Spożywczego

2024

nr 1

30--36

Tea is a crucial source of antioxidant compounds – polyphenols – in a standard daily diet. On average, Poles drink 2–3 cups of tea daily. Its regular consumption may prevent cardiovascular and metabolic disorders. The objective of the study was to compare the total polyphenol content (TPC) in various types of tea infusions prepared at different temperatures (T = 70/100°C) and brewing times (t = 2/10 minutes). Organic and conventional black and green teas were tested. The TPC was measured using the Folin-Ciocalteu spectrophotometric method and expressed as gallic acid equivalents (mg GAE/g of the sample). Each tea extract was assayed three times independently. In the organic types of teas, the highest TPC was found in green tea (95.65 ±3.96 mg GAE/g) brewed at 100°C for 10 minutes, while the lowest in black tea (51.65 ±2.39 mg GAE/g) brewed at 70°C for 2 minutes. Among the conventional teas, the highest TPC was also noted in green tea (91.83 ±2.29 mg GAE/g) brewed at 100°C/10 minutes and the lowest in black tea (48.88 ±2.20 mg GAE/g) at 70°C/2 minutes. Longer brewing times increased TPC in organic teas (in both black and green) and in conventional black tea (p <0.05), whereas higher temperature increased TPC only in organic teas (black and green); (p <0.01).