Properties of protein powder prepared from Cape hake by-products Original Research Article

Cape hake protein powder (HPP) was prepared by alkaline extraction, isoelectric precipitation and freeze drying. It contained 90% protein, 0.53% fat, and 1.44% ash. HPP showed high levels of Na, K, Ca and Mg but lower than in hake mince. The protein profile of HPP was similar to the raw material. The surface hydrophobicity and sulfhydryl group content of HPP were identical to those of the proteins before freeze-drying. The HPP had higher fat absorption capacity, lower emulsifying and foaming capacity than soy protein concentrate, pea protein isolate and egg white powder. The gel strength of HPP was medium (44.8 Nxmm) and was increased by addition of transglutaminase. Gels with different HPP concentrations showed a typical pattern of myofibrillar protein networks with a thermo-reversible behavior. The structure of emulsions prepared with HPP showed increasing complexity as the protein level increased. An increase in the magnitude of the viscoelastic functions and an increment in the magnitude of the zero shear rate limiting viscosity with increasing HPP content were observed.