Молекулярная гастрономия для креативных шеф-поваров (англ. язык) - страница 150

Молекулярная гастрономия для креативных шеф-поваров (англ. язык)

proteins, lipids, sugars, and enzymes) that contribute to the consistency and nutritional value of bread.

The part that forms the sticky mass however contains the insoluble proteins (the gliadines and the

glutenins) and is called gluten.

Flour in cooking

Flour is often added to mixtures for two reasons – to thicken a liquid (where the flour starch has an

important role) or to give strength to dough (where the insoluble flour proteins play a role).

Flour as a thickener

How it thickens: When flour as added to a hot liquid to thicken a sauce, the starch granules in the flour

will take up water and start to swell. The liquid molecules entering the granule break up some of the

bonding holding the starch molecules together, opening up the structure. The more water that enters

the granules, the more the granules will open up, so the more water can enter. The sauce will thicken

because firstly the liquid exterior to the granules is reduced, so less “free water” is available to let the

sauce freely flow. Additionally, these swollen starch granules impede the ease with which the liquid

can flow, further thickening the sauce. At around 50-60 °C, known as the gelatinisation temperatures,

the individual granules have swelled so much that lose their previously ordered structure and just

becomes an unorganised mixture of starch and water molecules.

As temperatures are heated further, from about 80°C, the swollen granules will leak amylose and

amylopectin molecules into the surrounding liquid. The long amylopectin molecule is especially

effective at thickening the sauce. At this point the sauce is at its thickest.

Left: raw starch granules. Middle: starch granules that have swollen on heating. Right: starch

molecules released from starch granules after further heating

III/V - 2 (of 3)

Thinning out: As temperatures reach above 93 °C, the sauce will start to thin. Excessive heat for too

long, heating at too high a temperature, or vigourous stirring cause the fragile starch granules to start

to break up into smaller fragments. Although this will cause more amylose to be released, the overall

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