Standard Operating Procedure: Tea Preparation

1. Purpose

This SOP details the procedure for preparing a cup of tea to consistent, high-quality standards based on current scientific evidence and international guidelines. The process is suitable for sensory evaluation, consumer service, or laboratory standardisation.

2. Scope

Applies to the preparation of black, green, white, and herbal teas using loose leaf or bagged tea in environments where consistency, safety, and quality are required.

3. Responsibilities

• Personnel preparing tea must follow this SOP to ensure reproducibility and quality.
• Supervisors must ensure all equipment is available and staff are trained.
• Sensory analysts (where applicable) must adhere to the process for valid results.

4. Materials and Equipment

• Fresh, potable cold water (preferably soft water; see Section 5.1)
• Kettle with variable temperature control
• Teapot or suitable brewing vessel (white porcelain recommended for sensory testing, see ISO 3103)
• Loose tea leaves or tea bags (specify weight per serving: see Section 5.2)
• Thermometer (if kettle is not temperature-controlled)
• Timer
• Teacup or mug
• Stirring implement (non-reactive, e.g., stainless steel or porcelain spoon)
• Milk (optional, if required for procedure)
• Scale (for weighing tea)
• Sieve or strainer (for loose leaf)
• Cleaning supplies

5. Procedure

• 5.1 Water Preparation: Use freshly drawn cold water. Soft water is preferred (low in calcium/magnesium ions) as hard water forms surface films and can suppress aroma and flavour. Pre-filter hard water if needed.
• 5.2 Weighing and Measuring: Measure 2.0 ± 0.1 grams of tea leaves (or one standard tea bag, typically 1.8-2.2g) per 200 ml of water. For precision, weigh tea on an electronic balance.
• 5.3 Teapot Preparation: Warm the brewing vessel by rinsing with hot water; discard rinse water.
• 5.4 Heating Water:
  • Black tea: 93-100°C (just off the boil)
  • Green/white tea: 65-85°C
  • Herbal tea: 96-100°C (boiling)
• 5.5 Infusion: Add measured tea to the pot or cup. Pour correct volume of hot water over tea. Start timer immediately.

  Tea Type	Water Temp	Steep Time
  Black	93–100°C	3–5 minutes
  Green	65–85°C	2–3 minutes
  White	65–85°C	2–3 minutes
  Herbal	96–100°C	5–7 minutes

• 5.6 Removal and Serving: Remove tea leaves or bag promptly at end of steep. Stir tea gently before serving (see "tea leaf paradox"-Einstein, 1926).
• 5.7 Addition of Milk (Optional):
  • Milk may be added before or after infusion, per tradition or test type.
  • Scientific recommendation: add milk first to hot cup, then pour tea (reduces protein denaturation and prevents skin layer).
  • For ISO 3103 sensory testing, add milk after infusion when tea is 65-80°C.
• 5.8 Final Steps: Serve immediately. Clean equipment after use. Record any deviations in procedure.

6. Notes & Cautions

• Incorrect water temperature can cause bitterness (too hot for green/white tea) or flatness (too cool for black/herbal tea).
• Oversteeping negatively affects flavour.
• Always use neutral, clean vessels for best taste.
• For international standardisation, see ISO 3103.

7. References

• BBC Science Focus (2022) The science of making tea.
• Burnett, D. (2011) How to make tea: science has the answer, The Guardian.
• Salgar Tea (2024) The science behind the perfect cup of tea.
• Tasting Table (2023) How to make better tea, according to science.
• Wikipedia (2024a) Tea leaf paradox.
• Wikipedia (2024b) ISO 3103.