Immunoreactivity changes during lupin seed storage proteins digestion

Abstract

Lupin seeds are already widely used as an ingredient in different food products. Their attractiveness is related mainly to their high protein content that is characterised by a favourable amino acid composition, as well as the desired technological properties. However, with the increase of lupin seeds usage in food manufacture, their potential allergic properties have been demonstrated. The aim of this work was to study the immunoreactivity changes taking place during the enzymatic hydrolysis of the major seed proteins of narrow-leafed (Lupinus angustifolius, varieties Zeus and Bojar) and yellow (L. luteus, var. Lord and Parys) lupin species. Two digestion systems were used, namely the in vitro model simulating digestion taking place in digestive track, and specific hydrolysis carried out by trypsin. The obtained hydrolysates were analysed by means of one-dimensional electrophoresis, and their immunoreactivity was assessed with the use of a sera pool from patients with lupin-specific IgE. An important reduction in allergenicity of lupin seed proteins was observed when trypsin digestion was applied. The digestion in the in vitro model revealed the possibility of formation of neoallergens which were identified on the basis of mass spectrometry results as β-conglutin fraction.