Industrial process proteomics : traceability and safety of protein components in lupin-based pasta product

Two-dimensional (2D) IEF/SDS-PAGE is a powerful tool to get molecular “pictures” of a food proteome and to monitor the processing effect of a given food item on its protein profile. In this work 2D electrophoresis has been used to monitor each step of lupin-based gluten-free pasta production. To this purpose 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 of half-processed products and dry pasta showed only minor differences among the samples during the industrial processing. These results, despite the intrinsic heterogeneity and complexity of lupin protein samples, indicate that the pasta making process have had no detectable effect on the covalent continuity of the main polypeptide backbones, suggesting that the polypeptides remained intact during the production process. The disulphide pattern did not change during the process, as well, 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. In conclusion, this work shows that taking 2-D electrophoretic “pictures” of the polypeptides at each relevant step of a food production process can be very useful to both production and quality control strategies. In addition, the traceability of specific protein components is made it possible in force of the technique high resolution also in complex food matrices. In this respect, the additional use of specific antibodies or other approaches, including mass spectrometry identification of specific spots, can be extremely valuable. Moreover, the importance of monitoring the presence/modification of biologically active protein components, such is the case of lupin g-conglutin or specific allergens, by this analytical approach is self evident.