Application of Filtration to Recover Solubilized Proteins During pH-Shift Processing of Blue Whiting (Micromesistius poutassou); Effects on Protein Yield and Qualities of Protein Isolates

Abstract

Previous studies of the pH-shift protein isolation process have shown that substantial amounts of solubilized proteins can be trapped in the sediments formed in the first centrifugation step of this process. As a strategy to improve the protein yield during pH-shift processing, the aim of this study was to evaluate how filtration as an alternative to centrifugation in the first separation step of pH-shift processing of blue whiting affected proteins yield and protein isolate characteristics (basic composition, polypeptide profiles, surimi gel quality and color attributes). The study comprised both the acid and alkaline versions of the method, and also fresh as well as frozen fish raw material. Results showed that the replacement of centrifugation with filtration substantially improved the protein yield by from about 38% to 62%, but also reduced the removal of lipid. There were no significant effects on gel quality. Protein isolates from fresh raw material were about 5 % whiter and frozen raw materials about 3% whiter with centrifugation as compared to filtration in the pHshift process. For surimi from fresh raw material centrifugation gave about 2 % whiter gels, while the gels from frozen raw material were about 3% whiter for filtered compared to centrifuged material. The whitest isolates and gels were obtained with acid processing of fresh blue whiting. Slight proteolytic breakdown resulting in fragments of 83 and 152 kDa was however noted with the acid process, especially when centrifugation was used.

Effect of organic acid on recovery yields and characteristics of rohu (Labeo rohita) protein isolates extracted using pH shift processing

“…Alkaline processed isolate gels had a whiteness value of 64.80, which was almost similar to the whiteness value of its isolates. These results were in agreement with the observations made by Nolsøe et al . They noted that the acid and alkaline processed blue whiting isolate gels had whiteness values of 75.4 and 69.2, respectively.…”

“…The factors that can influence the gel formation capacity of proteins are type of raw material (fish species), method of extraction and time of extraction . Similar findings for breaking force of acid processed isolates were reported by Nolsøe et al . They found that the acid and alkaline processed blue whiting isolate gels had a breaking force of 149.0 and 331.0 g , respectively, indicating the low gelling ability of the protein gels from acidic extraction process.…”

Physicochemical and functional characteristics of proteins treated by a pH‐shift process: a review

“…Nolsøe et al . (2011) also indicated that breaking forces of protein gels were highly associated with many factors such as the compositions of blue whiting, processing conditions. Blue whiting protein isolates with high lipid content and low protein content would form the protein gel with the low breaking force.…”

Fish discards management in selected Spanish and Portuguese métiers: Identification and potential valorisation

“…It must be mentioned that several studies on improving the properties and features of these products and possible changes in processes have been developed, such as the addition of hydrocolloids improving texture characteristics of the final product (Pérez-Mateos & Montero, 2000;Yoshie-Stark, Tsukamoto, Futagawa, Kubota & Ogushi, 2009;Pin, Laca, Paredes & Díaz, 2010;Nolsøe, Marmon & Undeland, 2011;Pérez-Mateos & Montero, 2000). The good results obtained could lead to feasible utilisation of these discards by fleets.…”

“…The good results obtained could lead to feasible utilisation of these discards by fleets. Others changes can be considered as an opportunity to make future surimi production more sustainable with a better utilization of the raw material (Nolsøe, Marmon & Undeland, 2011).…”