Cold brew green tea.

Lesson 1: why cold brew tastes sweeter

Every tea leaf holds three things that matter here. Amino acids, mostly theanine, which taste sweet and savoury. Catechins, which taste bitter and drying. And caffeine, which is bitter too.

Hot water pulls all three out fast. Cold water is selective. Amino acids dissolve readily even when cold. Catechins and caffeine come out much more slowly. So the balance in the cup shifts toward sweetness.

Japan's agriculture ministry notes that cold brewed green tea holds a higher proportion of epigallocatechin (EGC) than hot brewed tea, and that this has been studied in human trials that began in fiscal 2021. That is research in progress, not a health claim. It does show cold brew is more than a fashion.

Lesson 2: choose your leaf

Fukamushi leaves are finer, so they give up flavour and colour faster. Asamushi's whole needles take longer and give a clearer, more delicate tea.

Lesson 3: three ways to cold brew

Lesson 4: cold brew matcha

Matcha is a powder of the whole leaf. There is nothing to strain, so it is not brewed at all. It is mixed.

1. Sift 2 g of matcha into a jarSifting stops cold water clumps.
2. Add 200 ml of cold waterFiltered is best.
3. Seal and shake hardAbout 20 seconds, until frothy.
4. Pour over iceDrink straight away; the powder settles if it stands.

Lesson 5: food safety

Cold brewed tea has not been heated. Treat it like any fresh drink.

1. Clean bottle, washed in hot soapy water and rinsed.
2. Fridge the whole time. Never on the bench in summer.
3. Drink within the day.
4. Strain the leaves once it tastes right; left in, it keeps getting stronger.