Abstract:

Basic compositions contributing to turbidity of pearl oyster protein hydrolysates were investigated. Results showed that turbid materials were mainly composed of 54.3% crude protein and 26.1% ester. SDS-PAGE pattern confirmed that peptides with small molecular size were the major components of turbid materials; amino acid analysis revealed that hydrophobic amino acids in turbid materials were 42% and higher than the content in hydrolysates. SDS analysis exhibited more effective to dissolve turbid materials than guanidine hydrochloride, urea and sodium chloride. Moreover, particle size distribution analysis showed that SDS treatment could significantly reduce the particle size of turbid materials. Average particle size of turbid materials was reduced to 97.9 nm from 1954.3 nm in turbid materials at the concentration of 8% during SDS treatment. All of these investigations suggested that turbid system was formed by large molecular peptides through hydrophobic interaction. In contrast, lipids had little effect on the turbidity of hydrolysates.

Key words: pearl oyster protein, complex proteins, turbid, hydrophobic interaction