Week 11 Bake: Mix it badly on purpose

Bicarbonate, four black bananas, and a batter you stop stirring while it is still lumpy

3 May 2027

Ten weeks of building gluten, and today you spend three hours avoiding it. No yeast, no kneading, no bulk, no proof. The gas comes out of a reaction that starts the moment the flour gets wet and is largely finished within a few minutes, so the batter is mixed, tinned and in the oven inside ten. Every stroke you stir past the minimum makes the loaf worse.

Before the session#

Buy the bananas a week out and leave them on the bench. You want skins heavily black-spotted, and fully black is better than not quite there. The lecture covers why. What matters at the bench is that a ripe banana collapses to a purée under a fork while a firm one stays in nuggets that never disperse, and that the fruit is carrying the acid your bicarbonate of soda has to react with. Weigh them peeled: four medium bananas come to about 400 g.

Do not try to rescue under-ripe fruit with an hour in a 150 °C oven. The skin blackens and the flesh goes soft, so it looks like it worked, but ripening is enzymatic and the enzymes are dead within minutes of the heat reaching them. You get starchy, bland fruit and a loaf that tastes of very little.

Read the week 11 lecture first. The bench work is twenty minutes of actual mixing and it will not make sense unless you already know why soda needs an acid and powder does not.

In the session#

Three hours. About twenty minutes of it is mixing, and you will spend more of the afternoon reading loaves than making them.

0:00 — the formula. Weigh everything before you combine anything. Once the bowls meet there is no time to be looking for the cinnamon.

Plain flour, around 9% protein, not the bakers’ flour you have used since week

1. Now check the raising agents against the two baselines in the lecture. On flour weight alone, 250 g would take 2 teaspoons of baking powder, or half a teaspoon of soda in a batter that brings its own acid. This formula runs the soda half as much again as that, at ¾ of a teaspoon, because 400 g of banana and 150 g of brown sugar is a great deal of acid for it to find — the fault to avoid is soda left over, not soda used up. The half teaspoon of powder tops up the gas without shifting the pH any further.

0:15 — two bowls. Whisk the flour, soda, powder, salt and cinnamon together for a full thirty seconds. This is not a formality: a gram of soda that never left its own pocket of flour is a bitter yellow-grey spot in the finished crumb, and you will find it by biting into it. In the second bowl, mash the bananas flat, then beat in the sugar, the eggs and the butter. Let the butter cool to about 35 °C first — poured in hot it scrambles the egg into threads.

0:25 — the marriage, and the split. Tip the wet bowl into the dry bowl all at once and fold with a spatula, counting. Stop at about twelve folds, when the last streak of dry flour has just disappeared. The batter will be lumpy, dull and slightly ragged. That is what correct looks like.

Now divide it. Two thirds goes straight into a lined 900 g tin. The remaining third gets another eighty strokes with a wooden spoon, beaten until it is smooth and glossy, and goes into the smaller tin. You are baking your own control.

0:35 — bake, 175 °C. Fifty to sixty minutes for the big loaf, thirty-five to forty for the small one. Moderate heat, because the tin is deep and the batter is close to half water. At 200 °C the crust would set and colour inside twenty minutes while the middle was still liquid, and you would pull out a dark loaf that ran when you cut it.

The comparison is not perfectly clean and you should say so in your log: the beaten batter sat in the bowl four or five minutes longer, in a smaller tin, for a shorter bake. Stroke count is the variable you care about, but it is not the only one that moved.

Test with the skewer into the deepest point. Moist crumbs clinging to it are done, wet batter is not, and a bone-dry skewer means you are a few minutes late. The centre reads 96 °C. Expect the top to split: the crust sets after fifteen or twenty minutes and the centre keeps expanding under it.

1:00 — the soda bench. While your loaves bake, Idris cuts a third one made to this formula with three times the bicarbonate. Taste a corner. Soapy, faintly metallic, bitter on the finish — that is sodium carbonate sitting in the crumb, left behind once the batter ran out of acid for it to react with. Then look at it. Too brown for its bake time, domed hard, split wide open and sunk across the middle, because all the gas arrived in the first ten minutes and there was no set structure to hold the volume.

2:15 — cut both. Ten minutes in the tin, then out onto a rack. They will still be faintly warm, which is fine for reading the crumb and too early to judge the flavour. The twelve-fold loaf should be tender and a little irregular. The beaten one will be tighter, faintly rubbery, and shot through with narrow tunnels running up towards the crust — gas that could not push out in all directions through an elastic batter, so it channelled. Photograph the two cut faces together. It is the clearest before-and-after you will get all semester, and you made both halves from one bowl.

Afterwards#

Wrap the good loaf and leave it two days before you decide what you think of it. At 60% sugar on flour weight this crumb holds its water in a way a lean dough cannot, and banana bread is generally better on day two than on the day. An unsweetened tin loaf is past its best the morning after you bake it.

Log the stroke count, the oven temperature, the skewer time, the internal temperature and how ripe the fruit actually was. Week 11 sits inside the block marked by bake-off 3: the showpiece, which is worth 50%, and a chemically raised element is one of the few things in a showpiece you can mix and bake inside an hour.