Boucha (Kaga boucha)
ingredient / ingredient-boucha
棒茶
Boucha (Kaga boucha) is a kind of hojicha made by roasting tea stems, drunk mainly in Kanazawa, Ishikawa Prefecture. It is also called Kaga boucha or Kanazawa boucha.
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Reading the bitterness
Boucha is a kind of hojicha made by roasting tea stems, also called Kaga boucha or Kanazawa boucha. In an aroma analysis of commercial products, pyrazines ranked among the leading aroma components. Pyrazines are described as compounds associated with roasting and roasted aromas, offering a clue for thinking about the aroma of boucha.
An analysis comparing stems and leaves from the same tea plant showed a tendency for pyrazines, geraniol, and linalool to be higher in boucha. This is a comparison of peak intensity, not a measurement of the absolute amount of the compounds. Before roasting, the stems contained more amino acids than the leaves, and the authors consider this a contributing factor in the greater formation of pyrazines through reaction with sugars.
There is an analysis showing that the tea stems used as the raw material for boucha contain about half as much tannin and caffeine as the leaves, and twice as much amino acids. Based on the low tannin content, the paper inferred that the stems have little astringency and a bland taste. Another study that examined roasted stems recorded the aroma of a medium-roast stem as "Bitter aroma, burnt roasted aroma", and rated a lightly roasted sample as "Preferable roasted aroma". This was an experiment using raw material from Mie Prefecture, not boucha itself from Ishikawa Prefecture.
Sources for this overview
Checked for this overview: Matched the AEDA analysis's ranking of aroma components, in which pyrazines ranked among the leading ones. / Matched the tendency for three compounds to be higher in boucha in the stem-versus-leaf comparison, and the limitation that this is a peak-intensity comparison. / Matched the amino-acid content of the stems before roasting and the authors' discussion of the reaction process.
Comparison of Flavor Components between Kukicha (Stalk Green Tea) and Sencha (Green Tea)
Checked for this overview: Used for the stem's tannin, caffeine, and amino-acid content and the inference of little astringency
Checked for this overview: Used for the difference in aroma description by roasting intensity (e.g., Bitter aroma) and the regional limitation of the sample
Other names: 加賀棒茶 (ja)
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Boucha (Kaga boucha) →is a type of→ Hojicha
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Composition and content (4)
Scope: Stems (for boucha) and leaves (for leaf hojicha) from the same tea plant, plus 10 commercial boucha samples and 6 leaf-hojicha samples (mean price around 500 yen/100 g).
Note: Comparison of GC-MS peak intensities, using SPME for the comparison of commercial products.
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ingredient-boucha —has_composition→ (the claim sentence above)Scope: Stems and leaves from the same tea plant, before roasting.
Note: Fig. 10 compares bars in a graph. Only the ratio explicitly stated in the text (about 1.5 times) is included; no numerical values were estimated visually from the graph.
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ingredient-boucha —has_composition→ (the claim sentence above)Note: Based on the definition at the beginning of a paper that hojicha made by roasting stems is called 「棒茶」 (in translation: "Boucha").
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ingredient-boucha —is_a_type_of→ ingredient-hojichaScope: Commercial stem tea (1991, a commercial product at 300 yen per 100 g) compared against mid-grade sencha as a control (500 yen for the same amount); comparison of taste components by 13C-NMR
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ingredient-boucha —has_composition→ (the claim sentence above)Sensory (2)
Scope: Commercial boucha collected from Japanese-tea specialty shops in Ishikawa Prefecture.
Note: Aroma adsorption with a PDMS-coated stir bar, followed by GC-MS/AEDA analysis; FD factors were determined by sniffing the odor.
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ingredient-boucha —has_sensory_attribute→ (the claim sentence above)Scope: Ooishida stems from Mizusawa, Mie Prefecture, roasted with a Morita-type automatic continuous hojicha roaster; sample descriptions from Table I
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ingredient-boucha —has_sensory_attribute→ (the claim sentence above)Culture (1)
Scope: Kanazawa, Ishikawa Prefecture.
Note: This historical account is based on the authors’ reference to Kiroku Yonezawa, 『加賀茶業の流れ』 (in translation: "The Course of Kaga Tea Production"), 1976, Hokkoku Publishing. The primary source itself was not checked in this investigation; the account is secondhand.
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ingredient-boucha —has_historical_origin→ (the claim sentence above)