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ISO 3103 is a standard published by the "International Organization for Standardisation (commonly referred to as ISO), specifying a standardised method for "brewing tea, possibly sampled by the standardised methods described in ISO 1839. It was originally laid down in 1980 as BS 6008:1980 by the "British Standards Institution. It was produced by ISO Technical Committee 34 (Food products), Sub-Committee 8 (Tea).
The abstract states the following:
The method consists in extracting of "soluble "substances in dried "tea leaf, containing in a "porcelain or "earthenware pot, by means of freshly "boiling "water, pouring of the liquor into a white porcelain or earthenware bowl, "examination of the "organoleptic properties of the "infused "leaf, and of the liquor with or without "milk, or both.
This standard is not meant to define the proper method for brewing tea, but rather how to document the tea brewing procedure so sensory comparisons can be made. An example of such a test would be a taste-test to establish which "blend of teas to choose for a particular "brand or basic label in order to maintain a consistent tasting brewed drink from harvest to harvest.
A revised standard is currently under development as ISO/NP 3103.
The work was the winner of the parodic "Ig Nobel Prize for Literature in 1999.
To maintain consistent results, the following are recommendations given by the standard:
- The pot should be white porcelain or "glazed earthenware and have a partly "serrated edge. It should have a "lid that fits loosely inside the pot.
- If a large pot is used, it should hold a maximum of 310 "ml (±8 ml) and must weigh 200 g (±10 g).
- If a small pot is used, it should hold a maximum of 150 ml (±4 ml) and must weigh 118 g (±10 g).
- 2 "grams of tea (measured to ±2% accuracy) per 100 ml boiling water is placed into the pot.
- Freshly boiling water is poured into the pot to within 4–6 mm of the brim. Allow 20 seconds for water to cool.
- The water should be similar to the drinking water where the tea will be consumed.
- Brewing time is six minutes.
- The brewed tea is then poured into a white porcelain or glazed earthenware bowl.
- If a large bowl is used, it must have a capacity of 380 ml and weigh 200 g (±20 g).
- If a small bowl is used, it must have a capacity of 200 ml and weigh 105 g (±20 g).
- If the test involves milk, then it is added before pouring the infused tea unless that is contrary to the organisation's normal practice.
- If milk is added after the pouring of tea, it is best added when the liquid is between 65-80°C.
- 5 ml of milk for the large bowl, or 2.5 ml for the small bowl, is used.
The protocol has been criticized for omitting any mention of prewarming the pot. "Ireland was the only country to object, and objected on technical grounds.
In 2003, the "Royal Society of Chemistry published a press release entitled "How to make a Perfect Cup of Tea".