Starch granules swelling

Chaotropic salts, such as calcium chloride, decrease the starch gelatinization temperature to the extent that gelatinization may take place at room temperature. In contrast, non-chaotropic salts raise the gelatinization temperature. While fets and emulsifiers have minimal affect on the starch gelatinization temperature, they affect the rate of starch granule swelling after gelatinization (Hoseney, 1998). 

Starch granules are insoluble in cold water, but when a suspension in water is heated the granules swell and eventually gelatinise. On gelatinisation, potato starch granules swell greatly and then burst open cereal starches swell but tend not to burst. 

With the aid of X-ray diffraction diagrams, native starches can be divided into t) es A, B, and C. An additional form, called the V-type, occurs in swollen granules (Fig. 4.26). While types A and B are real crystalline modifications, the C-type is a mixed form. The A-type is largely present in cereal starches, and the B-type in potatoes, amylomaize, and in retrograded starches (resistant starch, cf. 4.4.4.16.3). The C-type is not only observed in mixtures of corn and potato starches, but it is also found in various legume starches. When suspended in cold water, air-dried starch granules swell with an increase in diameter of 30 0%. If this suspension is heated, irreversible... 

Desirable changes include higher onset temperature of starch granule swelling, increase in viscosity and stability, development of viscous pastes under pressure or acidic conditions, nonswelling of the starch granules under pressure cooking. 

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