Culinary class difference between starch potato and waxypotato

Waxy potatoes usually are less dense, tend to have thin skin and contain low levels of starch around (16% on a wet weight basis) and higher moisture. On the other hand, starchy potatoes are denser, have got thicker skins and contain more starch, which is about (22% on a wet weight basis) and less moisture. Professor McComber (Iowa State University, retired; J. Food Sci. 1988, 53: 1423-1426)

On a molecular level, the starch in waxy potatoes is made up of almost entirely of the large branched molecule known as amylopectin (around 74%) and the much smaller linear amylase molecule (26%). Both amylose and amylopectin are polysaccharides which act as forms of storage of glucose. Starchy potatoes are best used for deep frying because they are low in sugar and can be fried long enough for them to cook fully at the center without burning their outside. These potatoes also make the best choice for mashed potatoes since they fall apart easily when boiled. Waxy potatoes, on the other hand, are an excellent choice for boiling and roasting since they are low in starch, they usually maintain their shape after they are cooked. These potatoes are not the best when it comes to frying because their high moisture content makes them soggy and limp. Professor McComber (J. Agric. Food Chem. 1994, 42: 2433-2439)