and the intermediate fraction (see 3.5 Biochemistry). But these percentages vary among cultivars and with kernel development. For example, amylose percentage ranged from 20 to 36% for 399 cultivars of normal maize.[22][23] There are maize germplasm collected that range from less than 20 to 100% complement of amylopectin.[21] And waxy maize contains 100% amylopectin.[12]
Waxy starch is of main interest because fractionation of normal starch to obtain pure amylose or amylopectin is very costly.
Waxy endosperm is inherently a defect in metabolism, and its low frequency in most maize populations in the face of recurring mutations indicates that it is acted against by natural selection.[5]