prevents water to come into the lump (water can flow in, but very slowly).
In order to disperses starch granules from flour in water, one can either pour flour very slowly to hot
water, or to heat a paste made from flour and water, and add more an more water.
In both cases, amylose molecules from starch granules dissolves into hot water, and water molecules
can go in between the amylopectin of starch granules, making them swell. Under the microscope,
these swollen granules can easily be observed.
Also, flour contains quite a significant amount of proteins, which is responsible both for the desired
taste producing Maillard reactions and the unwanted formation of a skin and a higher risk of a burnt
The newer thickening agents
These traditional thickening agents are gradually getting replaced by more flexible and easy to use
thickening agents, such as different non protein containing flours and extracts from seaweed or
produced by fermentation.
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Non protein containing flours have the advantages of not forming lumps and a skin on cooking and not
forming tough doughs like bread due to absence of a gluten network. However the absence of proteins
will reduce the number of Maillard reactions that can occur to produce flavour. It is possible to buy
protein free wheat flour, but due to the slightly “floury” taste it has, protein free flours from other plant
sources are preferred.
Corn starch and rice starch are both obtained from breaking up the grains of the plants from which
they are derived, in a similar way to wheat flour, which is obtained by breaking up the grains of the
wheat plant. These flours tend to have fairly large starch granules, which have a fairly strong structure
that require a fairly high temperature to be gelatinised. They also contain relatively high amounts of
amylose – which makes them thicken fairly quickly as the amylose is released, and cause them to set
on cooling. Corn starch and rice starch do not contain any proteins, so are more pure is starch, and