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

Abstract

Impacts of processing technology (mechanical separation and pH-shift processing) on protein recovery from salmon, herring and cod backbones and the content of macro- and micronutrients in the recovered protein enriched products were investigated. Mechanical separation led to higher protein recovery compared with the pH-shift process and using both techniques, recovery ranked the species as herring > salmon > cod. However, the pH-shift process up-concentrated protein from herring and salmon backbones more efficiently than mechanical separation by removing more fat and ash. This consequently reduced n-3 PUFA and vitamin D content in their protein isolates compared with the backbones and mechanically separated meat (MSM). Cod protein isolate, however, contained higher levels of these nutrients compared with MSM. Mechanical separation concentrated vitamins E and C in salmon MSM but not for cod and herring. Opposite, pH-shift processing reduced levels of these two vitamins for cod and herring backbones, while vitamins D and C were reduced for salmon. For minerals, selenium, calcium, magnesium, and potassium were lower in protein isolates than MSM, while copper, zinc, iron and manganese were similar or higher. Overall, there is a major potential for upcycling of fish backbones to food ingredients, but processing technology should be carefully balanced against the desired nutrient profile and final application area.

Steam Explosion-Assisted Extraction of Protein from Fish Backbones and Effect of Enzymatic Hydrolysis on the Extracts

“…These fish byproducts, with low economic value, are usually treated as waste, leading to environmental problems. Particularly, fish bones are good sources of protein and bio-calcium [3]. After appropriate processing, these raw materials may find potential applications among a series of food products [4][5][6][7].…”

“…Recently, enzymatic hydrolysis, a mild and controllable method, has been widely used for the extraction of proteins and the production of protein hydrolysates from fish-processing industries [12,13]. However, the efficiency of the hydrolysis process for fish bone is very low, due to the complex bony structure's resistance to commercial proteases [3]. Overall, it is still difficult to completely extract proteins from the bone materials by enzymatic hydrolysis [14].…”

A Recyclable Dipping Strategy to Stabilize Herring (Clupea harengus) Co-products During Ice Storage

“…However, wild fisheries cannot expand further based on the endurance of ecosystems and climate change, and the expected aquaculture expansions will not be able to sustain the demand (Alexandratos & Bruinsma, 2012). Therefore, fish co-products are crucial contributions to meet this demand as they are high in protein and also contain important micronutrients such as long chained n-3 polyunsaturated fatty acids (LC n-3 PUFA), vitamin D, selenium, iodine, and vitamin B12 (Abdollahi et al, 2021). Several innovative techniques exist to separate muscle proteins from bone and skin of fish co-products, such as the pH-shift process, classic meat-bone separation, and enzymatic or non-enzymatic hydrolysis (Abdollahi et al, 2018;Nolsøe & Undeland, 2009;Rustad et al, 2011).…”

Quality of Protein Isolates and Hydrolysates from Baltic Herring (Clupea harengus membras) and Roach (Rutilus rutilus) Produced by pH-Shift Processes and Enzymatic Hydrolysis

“…However, the proportion of PUFAs of total lipids increased after the extraction from herring, but decreased after the extraction of salmon backbones. In a study by Abdollahi et al [ 46 ], protein isolate produced from herring backbones by alkaline pH-shift contained a considerably higher percentage of PUFAs compared with the raw material (43% vs. 24% of total fatty acids). In the present study, the proportion of PUFAs was statistically significantly ( p < 0.05) lower in the alkali-extracted isolates of both roach and B. herring, when compared with the raw material, whereas no statistically significant differences were observed between acid-extracted isolates and raw materials.…”