Boiling Techniques

Boiling is a term for cooking food submerged in hot water or other liquids such as stock or milk; this can range from a gentle simmer, where bubbles appear in one part of the pan only, to a rolling boil, where the water bubbles in a fast and agitated manner.

Rapid Boiling

A rolling boil is used to cook a variety of different foods; for example, pasta and rice. The boiling water expands the starch granules and makes them tender, whilst the rapid agitation prevents the pieces of pasta or rice from sticking to the pan or to each other.

Green vegetables are also best cooked in an open pan in rapidly boiling water; they become tender, whilst still retaining their bright colour and crispness. Salting the water well (1 tablespoon for every 1.75 litres or 3 pints) causes the water to boil at a higher temperature, cooking the vegetables even more quickly.

Rapid boiling can also be used to drive off moisture and reduce liquids to a thicker consistency. When making toffee or other sugar mixtures, a galloping boil allows the mixture to quickly reach the high temperatures required.


Gentle simmering is used to cook vegetables that would be damaged by vigorous boiling. Vegetables unlikely to discolour, such as carrots, parsnips, potatoes, beetroot and other root vegetables, are usually simmered in a covered pan; this preserves heat and helps to control fuel costs.