Alkaline Cooking, and What Khar Actually Does

Every home cook knows what acid does. Squeeze a lemon over something flat and it comes alive; that lesson is taught early and taught everywhere. Almost nobody is taught the opposite move, because in most cuisines there is nothing to teach it with.

Assamese cooking has kolakhar — an alkali filtered from banana-peel ash — and it does four distinct things that are worth understanding whether or not you ever cook a khar.

1. It destroys pectin, fast

Plant cell walls are held together largely by pectin, and pectin degrades much more quickly at high pH. This is why raw papaya in a khar turns tender in eight minutes when the same cubes in plain water would need twenty, and why it goes slightly translucent rather than simply soft.

The same principle is why a pinch of bicarbonate makes dried beans cook faster, and why it will turn them to mush if you overdo it.

2. It changes how protein holds water

Proteins hold the least water at their isoelectric point. Push the pH away from it in either direction and water-holding capacity goes up. Alkali pushes it up decisively, which is why fish cooked in khar stays moist and develops a springy, faintly gelatinous surface.

3. It accelerates browning

Maillard reactions run faster at alkaline pH. Part of the savoury roundness in a khar is not an ingredient at all — it is browning chemistry that the pH made possible at a temperature where it otherwise would not have happened.

This is also why pretzels are dipped in lye and why alkaline noodles brown the way they do.

4. It will make soap if you let it

Alkali plus fat is the definition of saponification. Overdose the khar in a pan with mustard oil in it and you are producing a small quantity of actual soap. That is the flavour people describe as "soapy" — it is not a metaphor.

Acid brightens. Alkali softens, rounds, and browns. Most kitchens only ever learn half the scale.

How to use it without ruining dinner

1. Never measure it blind. Homemade and bottled kolakhar vary in strength by a factor of several.
2. Add it in two stages, tasting between them. Stop while it still tastes like food.
3. Add it while the vegetable is cooking, not after. The textural work happens during cooking or not at all.
4. Leave the onion and garlic out. Alkali and aromatics blur each other.
5. If it tastes soapy, dilute and add salt. More cooking will not fix it.

If you want to see all four effects in one pot, the dish to cook is Maasor Muror Khar. The research behind it is in The Story of Khar.