Functional and Biochemical Characterization of Proteins Remaining in Solution After Isoelectric Precipitation

ABSTRACT

The resulting supernatant from the isoelectric precipitation of “sawdust” from Cape hake portioning and blue whiting muscle was concentrated by ultrafiltration and the retentate spray-dried. Two main peaks corresponding to molecular weights of 15 kDa and 65 kDa were detected in the supernatant from both raw materials; in the retentate the main proteins had approximately 18 kDa and 73 kDa, and some proteins with 59 kDa were detected in the permeate. The protein content was 74.0% and 70.0% for hake by-products and blue whiting, respectively. Dried proteins had relatively low emulsifying and foaming capacity but high foaming stability and were whitish in color. Hydrophobicity and sulphydryl content were similar to those from other protein sources.