Starch grains PART 1
Small granules of starch grains have a diameter from 1 to 30 microns of spherical or polyhedral shape. In the potatoes and bananas, starch grains are large, with oval diameter of 10-80 microns.
- Type 1 is inaccessible for the hydrolysis of small intestine, because it is protected by the cell walls or other structures. So are the cereals that contain whole grains or beans fragments and vegetables only partially milled.
- Type 2 is the native starch. It is known that raw potato starch is not easily digested by the human amylase. The exact mechanism of the resistors is not clear, but it seems that depends on the starch granules sizes the, the ratio between the amorphous crystallized material and polysaccharide architecture and the ratio of amylose and amylopectin. (Starch is a simple mixture of two polymers of glucose: amylose and amylopectin.)
Different foods have different concentrations of resistant starch. For 100 g of dry substance, white bread has 1 g, rice – 4 g, dry peas – 5 g, lentils – 9 g, potato – 5 g, and beans – 18 g. This is why 18 grams of resistant starch beans to 100 grams of dry substance, it’s so advisable for diabetics, because increase the blood sugar less.
Butyrate or butyric acid, resulted from the microbial fermentation of the resistant starch, it acts as a preferred energy source for the intestinal mucosal cells.
But the resistant starch presents other advantages: being the necessary intestinal flora substrate, favors the conversion of bacterial bile acids, which have escaped the small intestine absorbtion, and which are convert into secondary bile acids, deoxycholic and lithocholic; the intestinal mucosa is protected this way against prolonged bile acids contact, which could favor the emergence of cancer. And another thing: the resistant starch is the useful bacterial flora food of the large intestine. Sufficient quantities of resistant starch, favoring the development of indigenous microbial flora, make that the large number of useful bacteria to not allow the development of pathogens germs that would have penetrated in the digestive tract.
The oybeans resistant starch, for example, stachyose and raffinose. I saw that soy has the largest quantities of resistant starch.
It is interesting that soy contains an enzyme (alpha-galactosidase) which hydrolyses the alpha-1,6 links to the stachyose and raffinose, resulting sucrose and galactose.
The enzyme alpha-galactose is a very small fraction of soy protein. Adding it to the soy “meat” during the industrial preparation would lead to hydrolysis of significant stachyose and raffinose fractions into digestible carbohydrates, reducing, thus, the formation of gas that soy preparations usually produce.