arbohydrates:
Soybeans contain about 30% carbohydrates. These can be divided into two groups: soluble sugars ( sucrose 5%, stachyose 4%, raffinose 1% ) and insoluble "fibre" (20%). Raffinose is a trisaccharide composed of galactose,glucose and fructose linked in that order. Stachyose is a tetrasaccharide with the following structure: galactose-galactose-glucose-fructose. Raffinose and stachyose are not broken down by the enzymes of the digestive track but are fermented by the microorganisms present in the intestine, with the formation of intestinal gas. Flatulence, an inconvenience associated with the ingestion of pulses in general, is a factor which must be considered, sometimes, in the use of soybean products in human nutrition.
The insoluble fraction is a complex mixture of polysaccharides and their derivatives. The major part of this fraction consists of cell wall carbohydrates:cellulose, hemicelluloses and pectic substances. The insoluble carbohydrates are not digested by the enzymes of the gastro-intestinal track and can be characterized as "dietary fibre". They absorb water and swell considerably. Unlike other legumes, soybeans contain very little starch ( less than 1% ).