The milk from the coconut is used extensively in various Malaysian cuisines, Thai, Khmer and Lao cooking.
Coconuts do vary but on the average approximately half Kg (1 lb) of coconut yields approximately 250 ml (9 fl oz) of milk when the coconut is fresh.
The white grated coconut referred to in most recipes, is the coconut kernel.
When buying a coconut, usually, choose a freshly cut coconut with a dark brown skin for a rich sweet milk.

In cake recipes, which call for a "coarsely grated coconut", then choose one that has a light brown skin, which is younger and is softer in texture. When preparing "coarsely grated coconut" in cake-making, rub some fine salt over the coconut before grating. Next, place the grated coconut over rapidly boiling water in a steamer for 3 minutes. Cool before using it to sprinkle over the cakes.
By doing so, it will prevent the grated coconut from turning rancid or sour too soon.

Thick and Thin Coconut Milk

Thick coconut milk is the first extraction of milk from a grated coconut after adding a little water, while thin coconut milk is the second extraction after adding more water.

Coconut Extract (Malay pati santan )

is coconut milk extracted without additional water. An effective way to do this is by squeezing the grated coconut a little at a time, in a piece of fine muslin cloth.

Kerisik
When pati santan is cooked over low heat, stirring constantly for quite some time, it thickens and eventually coconut oil separates out from the grated coconut.
Drained from the oil, this grated coconut residue is crisp and rich brown, and is used in desserts and sambals. This is kerisik but not the only way of producing this product.