ABSTRACT
Starch is organized in discrete particles, granules whose size, shape, morphology, composition, and supramolecular structure depend on the botanical source. The diameters of the granules generally range from less than 1 µm to more than 100 µm, and shapes can be regular (e.g., spherical, ovoid, or angular) or quite irregular. Starch granules are partially crystalline particles composed mainly of two homopolymers of glucopyranose with different structures: amylose, which is composed of units of D-glucose linked through α-D-(1-4) linkages and amylopectin,
1.1 Introduction: The starch granule ............................................................ 1 1.1.1 Granular structure ........................................................................ 1 1.1.2 Starch gelatinization ..................................................................... 3
1.2 Sources and producers of starch ............................................................. 4 1.3 Starch applications .................................................................................... 6
1.3.1 Food applications .......................................................................... 8 1.3.1.1 Texturing, thickening/gelling, retrogradation
and freeze-thaw stabilizer, emulsifying agent, gel strength and clarity, and cold-water swelling ..... 8
1.3.1.2 Dextrins, sweeteners, and syrups .............................. 10 1.3.1.3 Health and functional foods ...................................... 11 1.3.1.4 Edible coatings.............................................................. 13
1.3.2 Nonfood applications ................................................................. 13 1.3 Final remarks ........................................................................................... 15 References .......................................................................................................... 15 Special thanks ................................................................................................... 19
the branching polymer of starch, composed of α-D-(1-4)-linked glucose segments containing glucose units in α-D (1-6) branches. Amylose is an essentially linear polymer, although evidence has suggested some branches in its structure. Consequently, 4-9% of the population called “intermediate material or amylose-like” has been considered part of normal and high amylose starches (Tang, Mitsunaga, and Kawamura, 2006). Amylose can also present as a hydrophobic helix, allowing the forming of a complex with free fatty acids, fatty acid components of glycerides, some alcohols, and iodine (Thomas and Atwell, 2005). Amylopectin is larger than amylose in most normal starches and their chains are classied as small chains, with an average degree of polymerization (DP) of about 15, and large chains, in which the DP is larger than 45. This unique conguration ordered in the packing arrangement contributes to the crystalline nature of the starch granule. This crystallinity reects the organization of amylopectin molecules within the starch granules, whereas amylose makes up most of the amorphous materials that are randomly distributed among the amylopectin clusters (Blanshard, 1987). Under polarized light, the starch granule shows a characteristic Maltese cross (Figure 1.1), reecting its birefringent structure, which was suggested as a correlation between the molecular and principal optic axes, underscoring that packing of the amylose and amylopectin is radial (Banks et al., 1972). This observation can be corroborated by results obtained by x-ray diffraction (Waigh et al., 1997).
