Native starches contain small amounts of phosphorus (Gracza 1984). Potato starch contains 0.07-0.09% phosphorus covalently bonded to the amylopectin fraction in the monoester phosphate form. Koch et al. (1982) determined the phosphorus content of native potato starch to 0.083%, which corresponds to a degree of substitution of 4.36 x 10-3. The starches used in the work reported in this thesis contain 0.06-0.29% phosphorus, with amylopectin potato starch having by far the highest content.
Potato starch contains only small amounts of lipids and proteins. The lipid content is very low, only about 0.06% and the protein content is also about 0.06% (Swinkels 1985).