Tieguanyin oolong tea infusion
ingredient / ingredient-tieguanyin-infusion
鉄観音
Tieguanyin oolong tea infusion is a drink made by infusing Tieguanyin tea leaves in hot water. The leaf-to-water ratio, water temperature, steeping time, and infusion number change how bitterness and astringency appear.
On this page (8 sections)
Reading the bitterness
The bitterness and astringency of Tieguanyin oolong infusion vary with the leaf-to-water ratio, water temperature, steeping time, and number of infusions. A study using an orthogonal regression design with Tieguanyin (5 trained panelists and 27 consumers) found that increasing the tea-to-water ratio, lowering water temperature, and shortening steeping time significantly reduced the score for the combined attribute "bitterness-astringency". The study assessed bitterness and astringency as a single combined attribute, not their separate effects.
A separate study of sensory properties and compounds in Tieguanyin oolong roasted for different lengths of time reported that bitterness remained stable as roasting time increased and identified EGCG (epigallocatechin gallate) and caffeine as major contributors to bitterness in the infusion. This result concerns roasting duration, however; it does not directly add evidence about infusion conditions such as leaf-to-water ratio, water temperature, steeping time, or infusion number.
In a study comparing stages of tea processing by electronic tongue and sensory evaluation, Tieguanyin (TGY) was rated significantly lower in both bitterness and sweetness than Jinguanyin (JGY). LC-MS metabolite quantification in the same study found significantly lower catechin and catechin-gallate contents in TGY than JGY at each processing stage, averaging about 1/15 as much. The authors argue that catechins are major contributors to tea bitterness because of their low thresholds.
Sources for this overview
Checked for this overview: Used the experimental result that leaf-to-water ratio, water temperature, and steeping time affect the combined bitter-astringent attribute.
Sensory and chemical characteristics of Tieguanyin oolong tea after roasting
Checked for this overview: Used the report that bitterness was stable across roasting times and the description of EGCG and caffeine contributions.
Checked for this overview: Tieguanyin was significantly less bitter and less sweet than Jinguanyin. / The catechin content of Tieguanyin was about 1/15 that of Jinguanyin.
Follow the connections
Tieguanyin oolong tea infusion →— sensory attribute→ bitterness →can be measured separately …→ astringency
Tieguanyin oolong tea infusion →— composition→ tea catechins →are main contributors to→ astringency
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (1)
Scope: Layer: Food. LC-MS metabolite quantification. Oolong tea 2 cultivars (Tieguanyin and Jinguanyin) compared across processing stages.
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ingredient-tieguanyin-infusion —has_composition→ compound-catechinsSensory (2)
Scope: Layer: food. Tieguanyin oolong tea, rated on a 0-10 scale (bitterness, astringency, sweet aftertaste, floral aroma, sweet aroma, roasted aroma) by a certified trained panel of 9 (5 men, 4 women, aged 25-48).
Note: While the bitterness score stayed stable even as roasting time and temperature increased, compounds related to roasted aroma and color (L* value) changed clearly. This runs counter to the naive assumption that roasting always increases bitterness.
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ingredient-tieguanyin-infusion —has_perceived_bitterness_unchanged_by→ "Roasting treatment (105°C for 1, 3, or 5 hours, plus an additional roast of 130°C for 1 hour applied to the 5-hour batch)"Scope: Layer: food. Electronic-tongue analysis and sensory evaluation comparing processing stages for 2 oolong cultivars, Tieguanyin and Jinguanyin.
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ingredient-tieguanyin-infusion —has_sensory_attribute→ sensation-bitterHow processing and cooking change it (1)
Scope: An orthogonal regression design and trained panel using Tieguanyin
Note: The evaluated attribute is the composite "bitterness-astringency." It does not claim to have varied bitterness and astringency separately.
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ingredient-tieguanyin-infusion —has_bitter_astringency_affected_by→ "Tea-to-water ratio, water temperature, steeping time, and number of infusions"