By the FDA’s definition, it is a non-sweet nutritive polysaccharide that consists of D-glucose units linked primarily by α-1-4 bonds and that has a DE of less than 20.

It is a white powder or concentrated solution produced by partial hydrolysis of starch from corn, potato or rice with acids and enzymes. (1)
 

DE or reducing sugar content is a measure of the degree of hydrolysis of starch. Starch has a DE of 0, compared to dextrose with a DE of 100.

Commonly, maltodextrin sold in the market has a DE between 3 and 20. A higher DE represents a greater extent of the hydrolysis. Several physical, chemical and functional properties, e.g. sweetness and viscosity are based on the extent of starch hydrolysis – DE.

With the increasing of DE, the average molecular weight decreases and it will have a slightly sweet taste which not occurs in the products with lower DE.

The higher the DE,

The lower the average molecular weight and the simpler the molecular structure
The lower solubility, viscosity (binding power), anti-crystallising power
The higher sweetness and hygroscopicity
The easier to have a browning reaction with protein
When DE > 20, the product is called glucose syrup instead of maltodextrin. (2)