Tärkkelysrakeet

Tärkkelysrakeet, also known as starch granules, are discrete particles of starch found within plant cells, particularly in storage organs like seeds, tubers, and roots. They are composed of amylose and amylopectin, two polysaccharides that form a crystalline structure. The size, shape, and birefringence of these granules are characteristic of the plant species and can vary significantly. For instance, potato starch granules are typically large and oval, while corn starch granules are smaller and more polygonal.

These granules are formed during a process called starch synthesis, where glucose molecules are polymerized and assembled into amylose and amylopectin chains. These chains then organize into semi-crystalline lamellae within the growing granule. The layered structure reflects the diurnal rhythm of starch synthesis and degradation in plants. Starch granules serve as a primary energy reserve for plants, providing glucose for growth and development.

In addition to their biological role, starch granules are of significant industrial and culinary importance. They are extracted from various plant sources and used as thickeners, stabilizers, and binders in food products. Their properties can be modified through processes like gelatinization, retrogradation, and chemical modification to achieve desired functionalities in different applications. The digestibility of starch granules by humans depends on their structure and processing.