What is hojicha? How one word, "green tea", becomes three packets

How one word produces three things this different

Two things can be moved: the roast and the blend. Both leave a trace on the packet, because the industry's labelling standard settled the words.

The blend: the words that define kukicha, genmaicha and mixed tea

Start with the blend. The Green Tea Labelling Standard (緑茶の表示基準) of the Japan Tea Central Public Interest Incorporated Association defines kukicha and bōcha as tea holding a large proportion of stems and leaf stalks separated out in refining, genmaicha as sencha or bancha with roasted rice added, and mixed tea as different tea types combined.

The roast: a finishing fire at 70–130°C, and roasting at 140°C and above

What separates hojicha from sencha is not the raw material but the heat added after the green tea is made. In the appendix to the same standard, "(Appendix, reference example) Classification of manufacture, processing and sale", the finishing fire at 70–130°C and roasting at 140°C and above sit on separate lines. It names neither the equipment nor the measuring point, and what it separates is not the kinds of tea but whether a packet may say "manufacturer" (製造者) or has to say "processor" (加工者). What that line divides is chapter 5.

Past that temperature, the direction depends on where the measurement was taken. In the report of the Tea Research Station, Kochi Prefectural Agricultural Technology Center, catechins, the source of astringency, fell the deeper the roast went: the dark roast of first-flush tea held about one fifth of the level in aracha, or unrefined tea (the 2013 data, where catechins and aroma were measured). The two pyrazines measured as an index of roast aroma came out highest at the light roast, in first-flush tea and karibancha alike. When the Industrial Research Institute of Ishikawa and others roasted stems at drum inner-surface temperatures of 180–220°C, all eight pyrazines rose with the temperature. The conditions differ, so the two are separate stories.

Blending never reaches the packet

Blending (gōgumi, 合組) alone never reaches the packet. It is the tea merchant's step of combining several aracha into the flavour of one bag, and it moves the figures too. In the caffeine table of the Ministry of Agriculture, Forestry and Fisheries, under the same infusion conditions, hojicha is given as 20 mg per 100 mL of infusion and genmaicha, with roasted rice in it, as 10 mg (both with 15 g of leaf, water at 90°C, 650 mL and 0.5 minutes; no blending ratio is published). The conditions table for roasting, and the two blending conditions, are still to be measured.