Evening, a cup on the table, and the hand stops. Through the steam comes the doubt: is this a reasonable hour to drink it? Next morning brings a latte in a paper cup, and an old bag of sencha turns up at the back of the kitchen.
What follows says, ahead of the chapters that answer them, where each of the three gets decided: caffeine, the latte, and roasting at home.
An evening cup and its conditions
Under the lamp, the hojicha in the cup looks a reddish brown. Caffeine turns out to be a question of how the tea was brewed.
The government's published table brews each kind of tea under its own conditions. Gyokuro's figure is eight times hojicha's, but gyokuro is brewed with a lot of leaf in very little water. Line them up again per amount of leaf, and the gap all but disappears.
The four rows of the table below are not under the same conditions. Only hojicha and genmaicha share them. The table supports one thing: without matching the conditions there is no fair comparison, and matching them is a later chapter. After the cup comes the paper one with the latte.
Figure 0-2-1Caffeine and infusion conditions by kind of tea
| Tea | Caffeine (mg per 100 mL of infusion) | Infusion conditions (leaf, water temperature, volume, time) | Leaf per 100 mL of water (calculated) |
|---|---|---|---|
| Gyokuro | 160 | 10 g leaf・60°C・60 mL・2.5 min | 16.7 g |
| Sencha | 20 | 10 g leaf・90°C・430 mL・1 min | 2.33 g |
| Hojicha | 20 | 15 g leaf・90°C・650 mL・0.5 min | 2.31 g |
| Genmaicha | 10 | 15 g leaf・90°C・650 mL・0.5 min | 2.31 g |
A paper cup, and the quantities
Lift the lid of the paper cup and sweet, milky steam rises. The latte turns out to be a question of ratio.
In one shop's published recipe, hojicha powder is dissolved with sugar and hot water into a syrup, then combined with warmed milk. The quantities are given by weight, so what went into the cup, and how much, can be read off the page. That the café cup and the home cup differ is not a matter of skill.
The recipe accounts for one set of quantities and nothing beyond. What to change to bring the two closer is a later chapter. After the latte comes the old sencha at the back of the kitchen.
Old sencha at the back of the kitchen
Open an old bag of sencha and a faint, dry, green smell comes out. Roasting at home is more tangled.
In a prefectural tea station's figures, a light roast barely lowered the caffeine. Only the dark roast brought it down, by around a tenth. No peer-reviewed paper on roasting in a household hōroku or frying pan turned up within the range searched, either.
That is as far as the evidence goes. The chapter on roasting at home begins by fixing the conditions and measuring. The figures and conditions are gathered just below.
The numbers in detail
- Chapters
- Caffeine is answered in chapter 1, the latte in chapter 2, and roasting at home in chapter 4.
- Caffeine
- The table is "About caffeine" from the Ministry of Agriculture, Forestry and Fisheries (Figure 0-2-1). Per 100 mL of infusion, gyokuro is 160 mg and hojicha 20 mg, an eightfold gap.
- Where the values come from: The Standard Tables of Food Composition in Japan, 2020 edition (eighth revision). The page was last updated on 28 August 2026.
- Gyokuro's conditions
- 10 g of leaf to 60 mL of water, or 16.7 g per 100 mL of water, more than seven times hojicha's 2.31 g.
- Per gram of leaf
- Lined up again this way, the eightfold gap shrinks to about 1.1 times [a calculated value].
- Latte recipe
- The one Kurasu publishes in Kyoto (4 July 2024).
- Roasting and caffeine
- From the Tea Research Station, Kochi Prefectural Agricultural Technology Center, in the caffeine table of the following year (2014 data). The light roast barely changed it; the dark roast was 6–13% lower.
- Extraction
- That report steeps 1.9 g of leaf in 200 mL of boiling water for 5 minutes. Values are per 100 mL of tea liquor.