A comparison of methods to quantify prolamin contents in cereals

Hydrophobic prolamins are endosperm storage proteins accounting for about 40% of the total protein in most cereals seeds. Despite the absence of a reference method, several procedures have been periodically published to quantify prolamins in cereals. The aim of this study was to compare a conventional fractionation assay (LND) vs three other methods: one based on sequential extractions (HAM) and two rapid turbidimetric procedures (L&H and DRO). Prolamins were extracted in duplicate on barley, corn and wheat samples. For the turbidimetric prolamin evaluation in barley and wheat, a universally available purified gliadin, as alternative to purified zein, was also tested as standard reference material (SRM). The extraction prolamin values were different among grain types (P0.05). LND agreed sufficiently well both with HAM and with L&H methods (R2=0.664 and R2=0.703, respectively, P0.05), whereas a higher prolamin quantification was obtained using HAM (P