Red tea, known in the West as black tea, is a fully fermented tea category whose processing involves withering, rolling, full oxidation (typically 80%–90%), and drying. The transformation of catechins into theaflavins and thearubigins during oxidation gives red tea its characteristic deep amber liquor, malty‑sweet aroma, and robust body. Because quality can vary widely based on cultivar, terroir, harvest season, and processing nuances, tea professionals rely on a structured sensory protocol to evaluate and compare lots objectively. The Six‑Factor Sensory Evaluation Method—examining appearance, liquor color, aroma, taste, infused leaf, and cleanliness—provides a comprehensive framework that aligns traditional tea‑tasting wisdom with modern analytical standards. This article details each factor, offering specific criteria, measurable ranges, historical references, and practical tips for both enthusiasts and beginners seeking to sharpen their palate and assessment skills.

1. Appearance (外形)

The visual inspection of dry leaves is the first step in the six‑factor protocol. Appearance reflects the care taken during plucking, withering, rolling, and drying, and it often predicts how the tea will behave during infusion. High‑grade red tea exhibits uniformity in size, shape, and color, indicating consistent processing and minimal leaf damage.

Key evaluation points

  • Leaf integrity: Whole, unbroken leaves or well‑formed tips are preferred; broken fragments suggest over‑rolling or excessive handling.
  • Size and shape: For orthodox red teas, ideal leaf length ranges from 2.0 cm to 3.5 cm, with a slender, slightly twisted shape; CTC (crush‑tear‑curl) grades appear as uniform granules measuring 0.5 mm–1.0 mm in diameter.
  • Color: Premium leaves display a dark, lustrous brown‑black hue with a slight golden tip (especially in Assamica varieties). A dull, grayish surface may indicate insufficient oxidation or moisture retention.
  • Uniformity: Consistent color and size across the sample suggest careful sorting; noticeable variation can point to mixed grades or inadequate sieving.

Historical texts such as Lu Yu’s