Black tea powder (5 g) was brewed in deionized water (50 mL) at 50, 70, and 90 °C for 4 min. The highest total phenolic content in the infusion (315 mg gallic acid equivalent/mL) was obtained at 70 °C as measured by the Folin–Ciocalteu assay described below. This brewing temperature and time were chosen for subsequent preparation of CSB.