The in vitro digestibility of native SPP in comparison with that of
commercial SPI, using the digestive pepsin–pancreatin system for
different digestion times, are shown on reducing SDS–PAGE
electrophoretogram (Fig. 1). SPP had one main band (Fig. 1a, Lane
2) which is similar to the report of Maeshima et al. (1985). After
pepsin hydrolysis for 30 min, the main band of native SPP remained. On further hydrolysis with pancreatin, the main bands
of native SPP still had no visible change, although the bands of
pancreatin hydrolysates became less dense. These results indicated
that SPP could not be easily digested by pepsin–pancreatin
enzymatic treatment.