Question 1

What does blanching actually do?

Accepted Answer

Briefly boiling food and then stopping the cooking immediately, usually in iced water. It serves several different purposes, and which one applies determines how long you do it for.

**Deactivating enzymes — the main reason for freezing.** Vegetables contain enzymes that continue working after harvest, degrading colour, texture, flavour and nutrients. **Freezing slows them but does not stop them**, which is why unblanched frozen vegetables deteriorate over months, developing off flavours and dull colour. A brief blanch **denatures those enzymes permanently**. This is not optional for good frozen vegetables and is the step most home freezers skip.

**Setting colour.** Brief heat drives out the microscopic air pockets between cells that scatter light, making green vegetables appear **more vividly green**. Stopping quickly prevents the longer-term chlorophyll degradation that dulls them.

**Loosening skins.** A short blanch and a plunge into cold water makes tomatoes, peaches and almonds peel easily, because the rapid expansion and contraction separates the skin from the flesh.

**Part-cooking.** Dense vegetables can be blanched ahead and finished quickly later — the standard method for preparing vegetables in advance, and why restaurant vegetables arrive perfectly cooked in minutes.

**Reducing bitterness or strong flavour**, by leaching soluble compounds into the water. Used for some brassicas and offal.

**Removing surface impurities** from bones and meat before making stock.

**Why the refresh matters.** Draining and leaving food to cool means it **continues cooking in its own heat** for several minutes, which for a green vegetable is precisely long enough to undo the benefit. Iced water halts it instantly. Drain well afterwards, since surface water dilutes sauces and forms ice crystals in the freezer.

**Blanching in oil** at moderate temperature is the first stage of proper chips — cooking the interior through before a second, hotter fry crisps the outside.

**Timings vary considerably** by vegetable and size, from under a minute for leaves to several minutes for dense roots. Overrunning defeats the purpose.

Question 2

Why do green vegetables go dull when cooked?

Accepted Answer

Because heat and acid destroy chlorophyll, converting the vivid green pigment into a drab olive one — and the change is chemically specific and largely preventable. What happens. Chlorophyll contains

Question 3

How does freezing preserve food, and what is freezer burn?

Accepted Answer

By immobilising water, which stops microbial growth and slows chemical reactions — freezing does not kill most microorganisms, it pauses them, which is the fact behind almost every practical rule

Question 4

Does cooking destroy the nutrients in food?

Accepted Answer

Some, sometimes — and it increases the availability of others, which is the part usually left out. Whether cooking is a net loss or gain depends entirely on the nutrient and the method. What cooking

Question 5

Why does my garlic turn blue or green?

Accepted Answer

It is a harmless chemical reaction, not spoilage, and it is more common in pickled garlic and in dishes with acidic ingredients. Garlic contains sulphur compounds and amino acids. When the cloves are

Question 6

Why does stock go cloudy?

Accepted Answer

Because agitation and high heat emulsify fat and suspend fine protein particles in the liquid, rather than letting them separate out — and once they are dispersed, they generally stay dispersed. What

Question 7

What is the difference between gelatine, pectin and agar?

Accepted Answer

Three setting agents from completely different sources, setting at different temperatures, with different textures — and they are not interchangeable in a recipe. Gelatine. A protein derived from

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