Roasting and hiire: the same fire, two different processes

Different names at the same height

Pick the packets up and they all weigh about the same in the hand. Yet the five names do not sit at the same level at all.

Each name points at a different layer. One names a method, one a part of the plant, one something added, and all three kinds are mixed together on one shelf. A name says which layer it belongs to, and no more. What those layers hold comes next.

Roasting, stems, toasted rice

Look into a packet of genmaicha and round grains show between the leaves. Hojicha names a method, kukicha a part of the plant, genmaicha something added.

Going by the national government's account, hojicha is named for roasting, kukicha for the stem, genmaicha for toasted brown rice. Because the layers differ, a hojicha made from stems is a perfectly sound combination. The fire in the name hojicha is one that arrives after the tea is already made.

The industry's labelling rules also write down the method and nothing else. Tea roasted over a strong fire, they say, with no line limiting the raw material to bancha. The tea roasted in research has been first-flush stems. The documents take us as far as the wording of the definition; next comes where the fire falls in the process.

A fire at the start, a fire at the end

At the end of the shelf sits a packet of kamairicha, pan-fired tea. The idea of firing in a pan catches the eye, much as it does on hojicha. The word may be shared, but the fire falls at a different point.

In kamairicha the fire comes at the very beginning of the making. That heat is what stops the enzymes working in the leaf. The roasting fire of hojicha comes again, once the tea is already finished.

What the sources establish is a difference of position in the process, nothing more. On the finishing side, one more fire is waiting.

One more fire on the finishing shelf

At the back of the businesses that finish and sell tea, there is a fire for drying aracha a second time. Hiire, the finishing fire, sits on the same shelf as roasting.

Hiire dries aracha, the unrefined tea, once more and brings up its aroma. It even has a target moisture figure, which the chapter on where hiire ends and roasting begins sets out. A national research institute describes finishing aracha as three steps: sorting, hiire and blending. The factories that do it belong mostly not to growers but to the people who sell tea.

Roasting and hiire overlap in temperature as well. They are still called separate processes because the time taken, the purpose and the way each is judged all differ. The differences in purpose and judgement come from the stage at which the fire arrives.

The sources show that these are the axes of difference, and that is as far as they go. The figures and where they come from are gathered at the end.

The toastiness was in the leaf

Each turn of the wooden spatula makes the toasted smell a little deeper. Its makings were inside the leaf all along.

The compounds that carried umami and sweetness turn into other things under heat. Nothing has been added from outside. The sources can say where the materials come from, and that is all. What heat forms out of them is the next part of the story.

A crowd of new aromas

Lean close to freshly roasted leaf and the aroma arrives in many layers at once. Roasted tea holds more than eighty compounds that were not in the leaf before.

A family of compounds formed when sugars and amino acids join under heat makes up most of the aroma. New compounds were also born from the source of umami together with sugars. The temperatures and times used in the research are tabled in the chapter that checks roasting temperatures.

The research names what was formed and stops there. Behind the new aromas, some things are being lost.

A second fire, after drying

Pinch the brown leaf and it is light and dry, much like hojicha. Oolong and roasted black tea both meet fire again after they have dried.

Set the processes side by side and both give dried leaf a second fire. Compare the times, though, and the charcoal roasting of rock tea runs orders of magnitude longer than hojicha's. The sources agree on where the fire falls, and not much more. First, the making of oolong from across the sea.

Drying, and drying again

Read a process chart from the top and the word drying keeps coming back. In oolong, the fire returns after the leaf has dried.

The oolong described by a tea research body across the sea is withered, fixed by heat, dried and rolled into balls. Last comes drying and roasting, the same shape as Japanese hiire.

Nor is there only one purpose. The same body lists making the tea keep longer, correcting green or unwanted notes, and giving the tea its own aroma. The sources set out the aims and leave it there. After purpose comes time over the fire.

Fires counted in seconds, fires counted in hours

Descriptions of charcoal-roasted rock tea give the time in hours. Against hojicha, the difference is one of orders of magnitude.

A shop selling the tea says that a single charcoal roast of rock tea takes close to half a day. Repeat it, and the total grows longer still. Hojicha roasting, in laboratory trials, lives in seconds and minutes.

The sources let a shop's account and a trial's figures sit side by side, and no more. After time, the black tea shelf.

Roasted black tea and the scent of fruit

The black tea shelf has its own packets marked roasted. A scorched smell is not the only place roasting can lead.

Roasted black tea is finished black tea given one more fire. Black tea is already dried with hot air in the making, so this roast is not its first fire. One tea farm roasts summer-picked black tea and speaks of a rich sweetness and a roasted aroma. Another roasts hard and says the result carries a sweet scent like peach and grape.

The reactions belong to the same family as those that make hojicha's aroma. A report on roasting rock tea says the roasted aroma moves towards a floral one while the tea is stored. The cultivars and processes differ, though, so the figures cannot simply be carried across.

What the word roasting means from one shop to the next is taken up in the following chapter. The figures and where they come from are gathered at the end.

The hotter, the toastier

Inside the sound of a turning drum, the leaf shifts colour little by little. Within the range tested, the higher the heat, the more toasty compounds formed, and the colour moved from yellow-green towards yellow-red.

The toasty compounds all came out higher at the higher temperatures. The colour drifted from the green side towards the red. What was not established is how hot the leaf itself became. Where that temperature was taken is the next question.

What was hot was the inside of the drum

The inside of a turning drum gets too hot to hold a hand near. The report's temperature belongs to the inner surface of the drum, not to the leaf.

The researchers read the drum's inner surface with an infrared thermometer. Other reports measured in other places, and some do not say where at all. How the measuring points differ is set out in this section's table.

The sources tell us which part of the machine was measured, and that is where they stop. Next, the stems that were roasted and how.

A line the thermometer cannot draw

Turn to the appendix and roasting and hiire sit on separate rows of a table. The border cannot be drawn on the temperature scale.

That appendix is not a document defining kinds of tea. It is a set of examples for sorting out who is responsible for a label, and it names neither the equipment nor where the temperature was taken. An old public trial called heating at a roasting-side temperature hiire. A study has also made hojicha at a temperature on the hiire side.

The sources show that the temperature is not the line, and no more. After temperature, the easiest difference to see is time.

The line is the stage the fire meets

Pour hojicha and the smell of fire rides up on the steam. The line is drawn not by time or temperature but by the stage at which the fire arrives.

Of the three, time shows the difference most readily. Laboratory roasting is counted in seconds, hiire in minutes or hours. There are long roasts too, though, so time alone cannot draw the line.

Purpose and judgement cannot be compared head-on, because they belong to different stages. That difference of stage was itself the line. Hiire meets aracha before it is finished; the roasting fire meets sencha and bancha that have already had their hiire.

The same fire aroma is marked down at the earlier stage and sold at the later one. The packet writes that fire as light roast or dark roast, and whether a shared standard lies behind those words is taken up in the next chapter. The sources place the line at the stage, and stop there. Time, purpose and judgement follow in that order.