Aggregation profile of 11S, 7S and 2S coagulated with GDL

The aggregation process of the proteins coagulated by glucono-δ-lactone (GDL) was monitored by using atomic force microscopy (AFM). Solutions of 11S, 7S and 2S proteins, after heating at 100 °C for 10 min, were mixed with GDL and formed aggregates with different aggregation profiles. When the three protein solutions (11S, 7S and 2S) were mixed with GDL and deposited onto the mica for 1, 2 and 4 min, 11S proteins formed the largest clusters of aggregates, 2S proteins formed smaller clusters of aggregates than 11S but bigger clusters of aggregates than 7S and 7S proteins formed the smallest cluster of aggregates. It was also found, by turbidity measurement, that when GDL was added to the three protein fractions, the level of turbidity was in the order of 11S > 2S > 7S. Both these results showed that, when GDL was added to the three protein fractions, the speed of aggregation was in the order of 11S > 2S > 7S.