Shokupan (Milk Bread)

Variations

• What the tangzhong does is tie up water. Dough and gluten presents hydration as one dial: under 50% is firm and rolls thin, over 70% is "sticky and awkward by hand, but it bakes into an open, moist crumb". Tangzhong is the way around that trade-off. Starch that has already been gelatinised holds on to several times its weight in water, so that water is not free to move around the dough. Total hydration is 75% and it handles like 65%.
• The number 65C is the whole thing. Wheat starch gelatinises at roughly 58-64C. Below that you have flour and milk; boil it well past 70C and the gel you just made breaks down and thins again. With no thermometer, the moment the whisk leaves lines behind it is the point.
• Only 5-10% of the flour. This recipe uses 30g of 300g, which is ten per cent. More than that and it goes past soft into gummy. Tangzhong is a device for improving a dough, not the dough.
• Bread going stale is not bread drying out. Wrapped in film it still goes stale. The starch that gelatinised in the oven slowly returns to a crystalline structure — retrogradation — and pushes out the water it was holding. Starch pre-gelatinised and stabilised does that more slowly, which is why a tangzhong loaf is still soft on day three.
• Three pages here already turn on the same phenomenon, each in a different direction. Lamington requires day-old cake, because only a staled cube survives being dipped on six faces; arancini needs rice that has gone cold and tacky in order to hold together at all; Spam musubi has to be pressed while the rice is still hot, before it retrogrades. This bread is the only one of the four built to slow it down.
• The difference from brioche is this bread's identity. Brioche buys its tenderness with fat — close to half the flour weight in butter. Shokupan carries ten per cent butter and lets water do the rest, which is why it tastes light enough to eat every day.
• On one axis with baguette and pumpernickel: the baguette is all crust, pumpernickel has no crust at all, and shokupan aims for the thinnest, softest crust it can manage. Turning it out of the tin the moment it leaves the oven, and the brush of milk, are both part of that.
• Yamagata and kaku. Baked uncovered it domes into peaks (yamagata, mountain-shaped); baked with a lid on the tin it comes out a square brick (kaku-shokupan). The photograph and this recipe are the yamagata. For the square one, fill the tin only to eighty per cent and put the lid on — the crumb comes out tighter, which suits sandwiches.
• How it is eaten. Cut thick and toasted, in the Japanese way. It is the bread in tamago sando, and it soaks up custard well enough to be worth using for French toast.

Tips

• Use strong flour. The wetter the dough, the more gluten it needs to hold itself up. Plain flour rises and then sinks (choosing flour).
• Cool the tangzhong properly. In a hurry, spread it thin and give it ten minutes in the freezer.
• Do not skimp on the kneading. This is where the dough most often fails. After the butter goes in, the right move at the point where it feels kneaded enough is another five minutes. You should be able to stretch it thin enough to see your fingerprint through it.
• Do not over-prove the second rise. Baked when it is already well above the rim it keeps expanding in the oven and then collapses at the sides. Just cresting the tin is right.
• Out of the tin at once. A few minutes in it and the sides go damp and fold inward.
• Do not slice it warm. The crumb of a just-baked loaf has not set, so the knife pushes it around instead of cutting.
• Keep it at room temperature. A fridge is the fastest staling temperature there is, and it will be dry within a day. What you cannot eat, slice and freeze, then toast from frozen (freezing and thawing).
• The sugar helps too. As what sugar does puts it, sugar holds on to water, so the 30g here is about moistness more than sweetness. Halve it and the loaf stales faster.