**2.4 Soy protein isolate**

Soy protein isolate is produced by refinement of SBM through a series of aqueous extractions with different pH levels that increase its protein content over 78% [26]. As, the processing of SPI does not have the aqueous alcohol extraction step, the saponin content of SPI (0.8%) is higher than that in SPC (0%) [27, 28]. Because of high protein content in SPI, the inclusion levels of this ingredient in aquafeeds could be lower than SBM and SPC that eventually reduce the total ANF input in aquafeed. On the other hand, it has been confirmed that the nutrients digestibility of SPI was higher than that of SPC, when it was replaced by 40% of FM in feed for rainbow trout (*Oncorhynchus mykiss*) [29].


*Bioactive component present in legumes and means of alleviation.*



#### *Legumes, Sustainable Alternative Protein Sources for Aquafeeds DOI: http://dx.doi.org/10.5772/intechopen.99778*


**Table 2.**

*Amino acid content of legumes products in comparison to fish meal.*
