Starch is present in most plant parts, but a viable amount of commercial extraction is primarily made from tubers and grains. Plants produce large stores of energy in the form of starch to be used as nutrition for seedlings and for themselves in order to survive long periods of hibernation and seasonal variations in weather. There is a history of humans extracting and consuming starch from over 50 species of plants.

Starches are chains of multiple glucose sugars bonded together. Starch occurs in two main forms, Amylopectin and Amylose. These two forms branches in a different way and have different properties to them. In plants these two starches occur in different ratios depending on the type of plant producing them, the variety of the plant, and the conditions it was grown under.

There is also an additional starch called Glycogen, often considered to be a highly branched version of amylopectin, which occurs in animals, fungi and bacteria but not in plants. This starch does not have any major culinary or commercial applications.

Commercial starches are refined from plant material, and not synthesized. The plant part being used is ground into a powder or paste and mixed with water. The starch will enter solution in the water and be leached from the plant material. this process must be done with cold water to prevent the starch granules from dissolving and forming a gel. The water starch mixture is then drained off and further refined using various techniques such as screens, filters, and centrifuges. The starch is then allowed to settle out of the water and dried.

The important properties of starches can be sorted into 3 main properties: starch particle size, and the percentage of amylose and amylopectin. Many plants produce Amylose and Amylopectin at about 20 to 25% amylose and 75 to 80% amylopectin by weight.

Starch molecules arrange themselves in the plant in semi-crystalline granules. Each plant species has a unique starch granular size: rice starch can be relatively small (about 2 microns) while potato starches have generally form larger granules (up to 100 microns).

Amylose is significantly less water soluble then amylopectin in cold water and requires considerably more heating to form a gel. This feature is what allows rice with high amylose content and low amylopectin content to freely fall apart after cooking. This is apparent in rice verities such as Basmati. Amylose particles most often form 300 to 3000 glucose bonds, and are significantly smaller then amylopectin molecules. The higher the amylose content, the less expansion potential and the lower the gel strength of the starch at concentration.

Amylopectin gels easily in water and has a tendency for its particles to stick to one another. High concentrations of amylopectin are responsible for the sticky qualities of sticky rice. Due to the branching nature of Amylopectin the molecules are dramatically larger then amylose. Individual molecules frequently have 2,000 to 200,000 glucose units.

Starches all have the three primary properties listed above, and they have these properties in different ratios and proportions. This is the main reason there are many commercially available plant starches, with diverse starch sources all the major variations of properties can be covered.

considerable variation can occur in the makeup of various starches. This is a rough guide to the behavior of many commercially available starches, further refinement is required to fully understand each commercially available starch product.

~40% Amylose
~60% Amylopectin
Medium granules 29 to 75 microns in size.

~25% amylose
~75% amylopectin
Small irregular particles 5 to 20 microns in size.

~0% amylose
~100% amylopectin
Small irregular particles 5 to 20 microns in size.

Waxy maize is almost totally made up of amylopectin.

~55% amylose
~45% amylopectin
Small smooth irregular particles 5 to 15 microns in size.

~75% amylose
~25% amylopectin
Small smooth irregular particles, 10 to 15 microns in size.

~15% Amylose
~85% Amylopectin
Small smooth particles 5 to 25 microns in size.

~20% Amylose
~80% Amylopectin
Large smooth round particles 15 to 75 microns in size.

~20% Amylose
~80% Amylopectin
Small irregular particles 3 to 8 microns in size.

~2% Amylose
~98% Amylopectin
Small irregular particles 3 to 8 microns in size.

~23.7% Amylose
~76.3% Amylopectin
Small polygonal particles 5 to 25 microns in diameter.

~0% Amylose
~100% Amylopectin
Small polygonal particles 5 to 25 microns in diameter.

~14% Amylose
~86% Amylopectin
Small polygonal particles 5 to 25 microns in diameter.

~25% Amylose
~75% Amylopectin
Wheat starch has two different particle sizes mixed together.
Medium round smooth particles 22 to 36 microns in size.
Very small round smooth particles 2 to 3 microns in size.

The majority of the source material is from an article on Natural Produce Insider ¹⁾
FDA report on high amylose corn starches ²⁾
Physicochemical Characterization of Arrowroot Starch ³⁾
Science direct on arrowroot starches⁴⁾
Structure and Functional Properties of Sorghum Starches Differing in Amylose Content ⁵⁾