Based on the mentioned charac- teristic of the various processed soybean products, SPH has the advan- tage in terms of protein availability and minimized anti-nutritional factors. Results of the property analysis on SPH showed an excellent pro- tein solubility, which is one of the most important functional properties of a hydrolysate. Protein solubility characteristic is required for many functional applications, especially for making emulsions, foam and gels. High solubility of the SPH can be due to the formation of smaller and more hydrophilic polypeptide units and the removal of insoluble fractions by centrifugation before vacuum drying of the soy peptide (Kristinsson and Rasco, 2000).
In summary, soy peptides can be utilized by fish as supplements (20% inclusion level in this study) to enhance growth and improve diet palatability. A higher dose of the soy peptides could result in a depression of growth. The soy peptides used in the experiment con- tained a mix of peptides and bioactive compounds. Thus, further in- vestigation should be conducted on the use of specific peptides or bioactive fractions for fish diets and its effects on growth, nutrient ef- ficiency, digestibility and postprandial absorption profile in the plas- ma of fish.