Application of two-dimensional electrophoresis to industrial process analysis of proteins in lupin-based pasta

Two-dimensional (2-D) IEF/SDS-PAGE is a powerful tool to get molecular "pictures" of food proteomes and monitor the processing effect(s) of a given food item on its protein profile. Still the use of 2-D approaches to this aim is rather uncommon. In this work, 2-D electrophoresis has been used to monitor the main steps of lupin-based gluten-free pasta production. Three different production lots, spanning over 1 year of pasta production, were analysed. Various samples at each critical production step, including seeds, raw materials, half-processed products and dry pasta, were used to generate the corresponding 2-D electrophoretic maps. Some differences in the protein profiles between the raw materials, i.e. lupin flour and lupin protein concentrate, were attributed to the different varieties which they arose from. On the other hand, the electrophoretic analyses showed only minor differences among the samples during the industrial processing. In particular, there was no alteration of the covalent continuity of the main polypeptide backbones. The disulphide pattern did not change during the process, either, and the constancy of the glycosylation pattern, as measured by the lectin Concanavalin A on the blotted maps, indicated that this molecular feature was not affected by the process too. The work shows how helpful the use of 2-D electrophoresis to trace proteins and evaluate the effects of the production processes in protein food manufacturing can be.