EFFECTS OF ROASTING AND BREWING CONDITIONS ON TOTAL POLYPHENOLS, ANTHOCYANINS, AND SENSORY QUALITY OF BLACK RICE TEA

Abstract

Aims: To evaluate the variation in total polyphenol content (TPC), total anthocyanin content (TAC), and sensory quality of black rice tea under different roasting and brewing conditions, and to determine suitable processing parameters for production.

Methods: The study was conducted using a single-factor experimental design. The effects of roasting time (8-14 min at 200°C), brewing time (5–20 min), and water temperature (80–100°C) on TPC, TAC, and sensory characteristics were sequentially investigated. The brewing ratio was 5 g of raw material per 100 mL of water.

Results: Roasting for 12 min yielded the highest TPC and TAC values, reaching 32.55 mg GAE/100 mL and 2.49 mg/100 mL, respectively. During brewing, both parameters peaked at 15 min (31.12 mg GAE/100 mL and 3.62 mg/100 mL) and subsequently declined with prolonged extraction. A water temperature of 100°C provided optimal extraction efficiency. The combination of 12 min roasting and brewing at 100°C for 15 min resulted in the highest bioactive compound content and sensory quality.

Conclusion: Roasting and brewing parameters significantly influence the bioactive composition and sensory attributes of black rice tea. The optimal processing condition was identified as roasting for 12 min followed by brewing at 100°C for 15 min.