Vegetables soften (pectin breakdown)
Also searched as: cooking until soft, falling apart, pectin, mushy vegetables
In short: is the glue between plant cells. Heat dissolves it and the vegetables soften. Acid slows this down, baking soda speeds it up.
Like mortar between bricks: once the mortar dissolves, the bricks slide apart easily.
What happens
Plant cells stick together through pectin. When cooking, the pectin slowly breaks down, the cells come apart and the vegetables turn soft. In acidic water this happens much more slowly, in alkaline water much faster. Gentle pre-cooking at about 55–60 °C (as a guide) can even strengthen the glue, because an firms it up.
Why it matters
Explains why potatoes stay hard in tomato sauce, why roughens the edges of roast potatoes and why .
Rules of thumb
- Add later if the vegetables are meant to soften.
- A pinch of baking soda in the cooking water makes the edges soft and rough.
- Pre-cook potatoes at about 60–70 °C if they should stay firm when fried: at this temperature an enzyme firms up the cell walls (as a guide).
Levers
3
In practice
2
Potatoes
Baking soda in the parboiling water loosens the edges, giving a craggy crust. Vinegar in the water keeps potato salad in shape.
Vegetables
Beans in tomato sauce stay firm longer. Cook them soft first, then add the acid.
Sources · 2
- Food52 Genius Recipes: Kenji López-Alts Ofenkartoffeln mit Natron
- Harold McGee: On Food and Cooking (2004), Kapitel Kartoffeln, Stärke, Frittieren