Gel-based and gel-free analytical methods for the detection of HMW-GS and LMW-GS in wheat flour

Durum wheat (Triticum turgidum L.) flour is instrumental for the production of pasta worldwide. The quality of this food rests on flour processing and on its protein content and composition. Gluten proteins as high and low-molecular weight glutenins (GS) are important to predict the flour technological property in pasta making. Different methods were compared to separate, identify and quantify GS in flours from two wheat cultivars. Sodium dodecyl sulphate-polyacrilamide gel electrophoresis (SDS-PAGE) gave in a fast way information about the GS assets. Two-dimensional gel electrophoresis (2D-GE) allowed for the highest resolution in detecting and quantifying single GS, subsequently identified by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS/MS). Reversed-phase high-performance liquid chromatography (RP-HPLC) is a non-gel alternative system for separation and quantification of single GS that when combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) gave information about their exact masses. This method gives also quantitative indications of each individual GS. Different GS patterns and contents were detected in the flour of the two cultivars, underlining the importance of these analytical methods before determining the best flour processing procedure in pasta making. The different methods were evaluated with a modular approach consisting of a grid of different parameters and a non-linear score within each module.