PROTEOMIC APPLICATIONS TO PROTEIN TRACEABILITY AND SAFETY STUDIES OF LUPIN-BASED FOOD PRODUCTS

Lupin seed is one of the richest in proteins, among grain legumes, thus representing an excellent source for the new needs of plant proteins in food products. 2D electrophoretic and mass spectrometry analyses can be of great impact to study lupin seed proteome, to evaluate the effects of technological treatments during food production and to monitor desirable/undesirable protein components such as biologically active proteins or allergens. The lupin seed 2D map (1) and its following updating have been used to identify the main protein components. Lupin maps show the complex pattern of heterogenous storage proteins. Of 357 spots detected, 70 of them were analyzed. Moreover, a 2D comparative approach between the total protein extract map and the purified major protein seed fractions maps, allowed to allocate 124 polypeptides within these fractions. Taking advantage of the availability of lupin protein 2-D map we also studied the presence, integrity and constancy of proteins throughout the industrial processing of a lupin-based pasta product. Samples, including seeds, raw materials, i.e. flour and protein concentrate, 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 were attributed to the different varieties which they arose from; on the other hand, no alteration of the covalent continuity of the main polypeptide backbones among the samples during the industrial processing were observed. In parallel, it was possible to trace a lupin putative dominant allergen (2), i.e. -conglutin, which is also considered the candidate molecule to the hypoglycemic activity of lupin seed extracts (3). This work shows that lupin proteome and related 2D electrophoretic maps can be very useful to both quality control strategies and traceability of specific protein components in food matrices. References (1) Magni et al. (2007). Phytochemistry 68: 997-1007. (2) Magni et al. (2005). J. Agric. Food Chem. 53: 4567-4571. (3) Magni et al. (2004). J. Nutr. Biochem. 15: 646-650.