Starch granules characteristics

Genovese, D. B. and Rao, M. A. 2003. Role of starch granule characteristics (volume fraction, rigidity, and fi tal dimension) on rheology of starch dispersions with and without amylose. Cereal Chem. 80 350-355. 

Pea starch granules are oval, sometimes fissured, with a diameter of 20-40 ym (13). Molecular and structural characteristics of the two main components of field pea starch—amylose and amylopectin—are important in determining functional properties (25,26). Smooth field pea starch concentrate contains 97.2% starch of which 30.3-37.8% is amylose (9,23,25-27), and wrinkled pea starch concentrate contains 94.8% starch, which is 64% amylose (26). The gelatinization temperature of smooth pea starch is between 64 to 69 C, and that of wrinkled pea starch is greater than 99 C to 115 C. Gelatinization temperature depends on maturity of field pea seed and amylose content (26,27). 

Birefringence (or double refraction) is the decomposition of a light ray into two rays when it passes through certain types of crystalline material. This occurs only when the material is anisotropic, that is, the material has different characteristics in different directions. Amylose and amylopectin polymers are organized into a radially anisotropic, semicrystalline unit in the starch granule. This radial anisotropy is responsible for the distinctive... 

Native starch granules exhibit three main types of X-ray diffractogram. The A type is characteristic of most starches of cereal origin the B t5q)e of potato (Figure 8.3), other root and tuber starches, and amylomaize starches and retrograded starch the C type of smooth pea and various bean starches. 

Kim, H. R., Hermansson, A. M., Eriksson, C. E. (1992). Structural characteristics of hydroxy propyl potato starch granules depending on their molar substitution. Starch, 44,111-116. 

Starch, another of the most abundant polymers of glucose, is stored by most green plants in a semicrystalline form in numerous small granules. These granules, which are usually formed within colorless membrane-bounded plastids, have characteristic shapes and appearances (Fig. 4-6) that vary from plant to plant. One component of starch, amylose, is a linear polymer of many a-D-glucopyranose units in 1,4 linkage (Fig. 4-7) as in maltose. Starch granules always contain a second kind of molecule known as amylopectin.58... 

In practice, the test is based almost exclusively on the recognition of the starch granules, which exhibit characteristic shapes for starches derived from different plants. 

Concerning bread, characteristics such as cell wall thickness, cell size, and uniformity of cell size affect the texture of bread crumb (Kamman, 1970) and also the appearance, taste perception, and stability of the final product (Autio and Laurikainen, 1997). Crumb elasticity can be predicted from its specific volume and is strongly affected by the amylose-rich regions joining partially gelatinized starch granules in the crumb cell walls (Scanlon and Liu, 2003). 

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