Structural, functional, and sensorial properties of protein isolate produced from salmon, cod, and herring by-products

Abstract

Nutritional, structural, functional, and sensorial properties of protein isolate developed from salmon (Salmo salar), cod (Gadus morhua), and herring (Clupea harengus) by-products using the pH-shift method was studied. Function of the proteins in an emulsion system in terms of viscoelastic properties was also evaluated. Regardless of origin, the proteins showed satisfying nutritional value as reflected in their high essential amino acid content. The proteins contained significantly (p < 0.05) higher proportion of active sulfhydryl groups and surface hydrophobicity compared to whey and egg white protein reflecting conformational changes caused by the pH-shift process. Solubility, emulsion, and foaming capacity of the proteins showed a trend similar to soy protein and dependent on their origin. Cod protein had better emulsion and foaming capacity than salmon and herring proteins which was in line with its high surface hydrophobicity and myosin heavy chain content. Emulsions developed from cod and salmon proteins showed substantially better viscoelastic properties, with higher stability and viscosity compared to herring protein emulsions. Cod protein scored low for sensorial attributes related to lipid oxidation while herring protein showed high levels of fishy and rancid flavor and odor. Altogether, results showed that the proteins from fish filleting by-products have potential to be used as food ingredients, but their application would be governed by their origin and sensorial properties.

Proximate Composition and Nutritional Profile of Rainbow Trout (Oncorhynchus mykiss) Heads and Skipjack tuna (Katsuwonus Pelamis) Heads

“…The total contents of essential amino acids in the rainbow trout heads and skipjack tuna heads were 41% and 40%, respectively. These results were in accordance with the contents of essential amino acids of salmon ( S. salar ) by-products (38%) [8] and red salmon heads (37%) [30], but were higher than those of herring ( C. harengus ) heads (31%) [5] and Atlantic salmon heads (23%) [24]. Properties of low-cost, high-protein contents (Table 1) and high essential amino acids contents (Table 2) indicate that rainbow trout heads and skipjack tuna heads may be used as materials for preparing high-quality protein.…”

“…Panpipat and Chaijan recycled protein isolates from bigeye snapper ( Priacanthus tayenus ) heads and evaluated their functional properties [7]. Abdollahi and Undeland investigated the nutritional, structural, functional, and sensorial properties of protein isolates developed from salmon ( S. salar ), cod ( Gadus morhua ), and herring ( C. harengus ) heads, indicating their potential as food ingredients [8].…”

Impact of Processing Technology on Macro- and Micronutrient Profile of Protein-Enriched Products from Fish Backbones

“…Both MSM and protein isolates of the three species had lower content of nonessential amino acids than the backbones, especially proline and glycine ( Table 2 ) which are enriched in the collagenous residues [ 31 ] being removed in mechanical separation and pH-shift processing. These findings agreed with our previous studies where we subjected mixed fish processing coproducts to pH-shift processing [ 11 , 31 ]. For herring, MSM and protein isolates also had reduced content of some other nonessential amino acids including arginine, tyrosine, aspartic acid and glutamic acid compared with its backbones.…”

“…The process has been widely investigated as a tool to produce food-grade high-quality gel-forming proteins, and most recently also fish oil, from fish processing coproducts [ 9 ]. The process can effectively concentrate proteins of fish processing coproducts by removing the bone residue and some of the fat resulting in a protein paste with good levels of essential amino acids and good functional properties [ 10 , 11 ]. However, based on the addition of significant amounts of water, part of the nutrients in the used raw material might be unintentionally removed by cofloatation or coprecipitation during the first centrifugation step and/or by solubilization into the water phase which is partly removed during the dewatering step.…”

Physico–chemical characteristics of fish flour prepared from locally available small indigenous fish species of Assam

“…The lower bulk density of fish flour prepared from Puntius sophore can be related to the lower protein content compared to fish flour prepared from Amblypharyngodon mola. Bulk density in similar range, that is, between 0.49 g/ml and 0.60 g/ml was observed by Abdollahi and Undeland (2018) in their study on evaluation of functional characteristics of fish protein powder developed from Salmon, Cod, and Herring by products. Higher bulk density is an indicator of suitability of the developed flour for utilization as food ingredients in food preparations (Chandra & Samsher, 2013).…”