Fish proteins
(Food ingredient derived from marine or freshwater fish — concentrates, isolates, hydrolysates)

Description

• Fish protein as a food ingredient consists of high-protein powders or pastes obtained from edible fish muscle and/or by-products (frames, trimmings, skin, heads, viscera where allowed).

• Main commercial forms:

  • fish protein concentrates (FPC),

  • fish protein isolates (FPI),

  • fish protein hydrolysates (FPH, peptide-rich).

• Typically a light cream to beige powder, with odour and taste ranging from very mild/neutral (highly refined isolates) to distinctly fishy/savoury (concentrates, some hydrolysates).

• Used to increase protein content, improve texture and provide savoury notes in a wide range of foods, supplements and specialised nutrition products.

Indicative nutritional values (per 100 g dry fish protein powder – generic ranges)

(Values vary with species, fat removal, and process; numbers below are typical for human-grade fish protein powders.)

• Energy: ≈ 330–400 kcal

• Protein: ≈ 70–90 g

• Total fat: ≈ 2–10 g

  • first occurrence: SFA/MUFA/PUFA = saturated / monounsaturated / polyunsaturated fatty acids.
    In most fish protein powders, total fat is modest and the residual fraction is mainly unsaturated, with a smaller SFA share and significant n-3 PUFA (especially EPA and DHA), plus some n-6. There are no industrially produced trans fats; only small amounts of natural marine trans isomers may be present.

• Carbohydrates: 0–5 g (residual glycogen, process aids)

• Ash: ≈ 3–10 g (minerals; higher if bone fractions are present)

• Sodium: ≈ 100–800 mg (very process-dependent; may be low in isolates and higher in salted/concentrated products)

• Micronutrients (variable, species- and process-dependent):

  • B-group vitamins (especially B12, niacin),

  • minerals such as phosphorus, selenium, iodine (marine fish), iron, zinc, calcium (if bones included).

Key constituents

• Proteins

  • Myofibrillar proteins (actin, myosin) from fish muscle → key for gel formation, water binding and texture.

  • Sarcoplasmic proteins (enzymes, myoglobin and other water-soluble proteins).

  • Collagen/gelatin if skin, bones or connective tissue are included.

• Amino acid profile

  • Fish protein is a complete protein with all essential amino acids in favourable proportions.

  • Typically rich in lysine, leucine, isoleucine, valine, threonine, making it suitable for growth and tissue maintenance.

• Lipid fraction

  • Residual fish oil, richer in long-chain n-3 fatty acids (EPA, DHA) than many terrestrial animal fats, plus SFA and MUFA.

  • In most high-protein powders the fat fraction is relatively small, so they are not major EPA/DHA sources compared to oily fish fillets, but still contribute small amounts.

• Minerals & bioactives

  • Phosphorus, selenium, iodine (marine fish), iron, zinc and others in variable levels.

  • In fish protein hydrolysates (FPH), short peptides may show antioxidant, antihypertensive or other bioactivities, depending on process and raw material.

Production process

(Simplified, covering FPC, FPI and FPH.)

1. Raw material handling

   • Edible fish species (whole fish or by-products) received chilled or frozen.

   • Visual and odour inspection; removal of non-edible fractions as required by regulation.

   • Washing and size reduction (mincing).

2. Fish protein concentrate / powder (FPC)

   • Cooking or pH-shift extraction to denature proteins and separate oil and water-soluble components.

   • Centrifugation/decanting to remove oil; screening/pressing to separate bones and solids.

   • Concentration of the protein-rich phase and drying (spray drying, drum drying or similar) → free-flowing powder.

3. Fish protein isolate (FPI)

   • Application of pH-shift technology: proteins are solubilised at very low or high pH, while most lipids and insolubles are removed.

   • Proteins are then precipitated near their isoelectric point, washed, dewatered and dried → high-purity protein (often >80–90%) with reduced colour, flavour and ash.

4. Fish protein hydrolysate (FPH)

   • Minced fish or by-products are treated with food-grade proteases under controlled pH, time and temperature.

   • Hydrolysis breaks proteins into peptides → enzyme inactivated by heating.

   • Oil and insolubles are separated; the peptide-rich liquid is clarified, concentrated and spray-dried or used as a liquid concentrate.

5. Finishing and packaging

   • Sieving and metal detection.

   • Packaging in multi-layer bags, drums or big bags (often nitrogen-flushed) to limit oxidation and moisture uptake.

Physical properties

• Form: fine powder or small granules; free-flowing when dry.

• Colour: white to light cream/beige (lean, refined products) or darker beige/brown (products with more lipids or blood pigments).

• Odour/flavour: from almost neutral to distinct fish/savoury; hydrolysates can have strong umami notes.

• Solubility:

  • FPC/FPI: dispersible in water; solubility depends on pH and ionic strength.

  • FPH: generally highly water-soluble, even at a wide pH range.

• Functional properties: water-holding capacity, oil-binding, gelation, emulsifying and foaming ability, depending on the specific product.

Sensory and technological properties

• Sensory

  • Refined isolates can be relatively mild in taste and smell, suitable for neutral-flavoured foods.

  • Less refined concentrates and hydrolysates provide pronounced fish or marine savoury notes, useful in broths and savoury snacks.

• Technological

  • Gel formation: strong gels in thermal processing (similar principle to surimi) → useful in fish balls, patties and analogues.

  • Water and fat binding: improves yield, juiciness and texture in meat/fish products and prepared dishes.

  • Emulsification and foaming: enables stable emulsions in sausages, spreads, sauces, and contributes to structures in aerated products.

  • Heat stability: many dried fish protein ingredients remain functional after heat treatments used in canned or retorted foods, though functionality depends on specific process history.

Food applications

• Home / foodservice (indirect use)

  • Less common as pure labelled ingredient; functionality is more often delivered via surimi, fish pastes, fish cakes and other structured products.

• Food industry

  • Protein enrichment of:

    • soups, sauces, fish soups and chowders, ready meals;

    • bakery and snack products with savoury/seafood profile;

    • high-protein bars, drinks, instant soups (especially with low-odour isolates or hydrolysates).

  • Structure and texture in:

    • fish balls, fish cakes, surimi products, seafood sausages;

    • meat/fish analogues, burgers, nuggets, hybrid animal–plant products.

  • Flavour applications:

    • FPH used in bouillons, stock cubes, seasoning blends, sauces and snack coatings for umami and “seafood” notes.

  • Specialised nutrition:

    • potential use in sports nutrition, medical nutrition and complementary foods, where a high-quality, hypo-lactose, non-dairy protein source is needed (fish allergy must still be considered).

Nutrition & health

• Fish protein powders provide:

  • High-quality complete protein, with a high biological value and all essential amino acids.

  • Small to moderate amounts of marine n-3 fatty acids (EPA, DHA) where fat is not completely removed.

• Human and animal studies on fish protein ingredients suggest possible:

  • beneficial effects on lipid metabolism,

  • modest improvements in glucose tolerance or insulin sensitivity in some contexts,

  • support for lean body mass maintenance when used as part of a balanced diet.

• These ingredients are foods, not drugs: any health effect depends on the overall diet, dose, and lifestyle.

• Compared with some other protein sources, fish protein is:

  • naturally lactose-free and gluten-free;

  • rich in certain micronutrients (e.g., B12, selenium, iodine) when not removed during processing.

Portion note:

• Typical contribution in enriched foods and supplements:

  • 5–25 g of fish protein per serving, whether as part of a bar, shake, fortified soup or main dish.

Allergens and intolerances

• Fish is a major allergen in most regulatory frameworks.

• Fish protein ingredients (FPC, FPI, FPH) must be:

  • Clearly labelled as fish-derived;

  • Avoided by individuals with fish allergy, even if taste and smell are mild.

• Cross-contact with other allergens (crustaceans, molluscs, soy, milk, gluten, etc.) depends on the facility and must be controlled within HACCP plans.

• Hydrolysates may be better tolerated by some people with non-allergic digestive sensitivities, but they are not safe for fish-allergic consumers.

Quality & specification (typical topics)

• Composition

  • Protein content (e.g., ≥ 70–80% on dry basis for many FPP/FPC/FPI).

  • Moisture, fat, ash, and sometimes defined maximums for sodium or specific minerals.

• Functional parameters

  • Solubility at different pH values.

  • Emulsifying capacity and stability.

  • Water-holding capacity and minimum gelling concentration.

• Oxidation and sensory

  • Peroxide value, anisidine value, or TBARS for lipid oxidation.

  • Organoleptic checks (rancidity, off-odours).

• Microbiological

  • Limits for total plate count, yeasts, moulds, and absence of pathogens (Salmonella spp., Listeria monocytogenes, etc.).

• Contaminants

  • Heavy metals (Hg, Pb, Cd, As), dioxins/PCBs and other contaminants must comply with food regulations.

Storage & shelf-life

• Store in a cool, dry, well-ventilated place, away from strong odours and light.

• Use sealed multi-layer bags or drums with good moisture and oxygen barrier; nitrogen flushing is common.

• Typical unopened shelf-life: 12–24 months for high-quality powders with low moisture and antioxidants.

• After opening:

  • reseal tightly;

  • minimise air/moisture exposure;

  • use within a timeframe specified by the manufacturer (often a few weeks to months).

Safety & regulatory

• Produced under GMP/HACCP with critical control points for:

  • freshness and hygienic quality of incoming fish;

  • time–temperature management during processing;

  • hydrolysis conditions (for FPH);

  • drying parameters and packaging.

• Regulatory aspects include:

  • use of approved fish species suitable for human consumption;

  • compliance with limits for heavy metals and environmental contaminants;

  • authorisation and labelling of any food additives (antioxidants, acidifiers, etc.);

  • in certain regions, evaluation as novel food for specific types of hydrolysates or for vulnerable groups (e.g., infant formula, medical nutrition).

Labelling

• Ingredient names can include:

  • “fish protein”, “fish protein concentrate”, “fish protein isolate”, “fish protein hydrolysate”, or “cod protein”, “salmon protein”, etc.

• Finished products must indicate:

  • presence of fish in or near the ingredient list (allergen statement);

  • nutrition declaration (including protein content);

  • storage conditions, best-before date, net quantity, batch/lot identification;

  • country of origin or manufacturer as required.

Troubleshooting (formulation & process)

• Strong fishy or rancid odour

  • Cause: oxidation of residual lipids, poor raw material quality or extended storage.

  • Actions: improve raw material handling and chilling, use antioxidants, choose more refined grades, improve packaging/oxygen control.

• Poor solubility or sediment in beverages

  • Cause: denatured or aggregated proteins, high mineral content, unsuitable pH.

  • Actions: adjust pH/ionic strength, select a more soluble hydrolysate or isolate, modify hydration/processing steps.

• Weak gel or crumbly texture in structured products

  • Cause: insufficient myofibrillar protein, excessive hydrolysis, low protein concentration.

  • Actions: increase protein level, blend with other gelling proteins/hydrocolloids, adjust heating profile.

• Too dark colour

  • Cause: excessive heat load during drying, high blood content, Maillard reactions.

  • Actions: milder drying, better trimming, selection of lighter-coloured grades.

Sustainability & supply chain

• Fish protein ingredients can strongly support circular economy by using fish by-products, increasing overall yield from each fish.

• Key sustainability aspects:

  • sourcing from well-managed fisheries or sustainable aquaculture;

  • efficient use of all fractions (oil, protein, bones, skin) to minimise waste;

  • treatment of processing effluents with high BOD/COD, often via anaerobic digestion or advanced wastewater treatment;

  • optimisation of energy consumption in cooking, hydrolysis and drying.

• Good supply-chain and stock management (FIFO) helps maintain quality and reduce losses.

Main INCI functions (cosmetics/personal care)

• Related ingredients in cosmetics often appear as:

  • Fish Collagen, Hydrolyzed Fish Protein, Hydrolyzed Collagen, etc.

• Typical roles:

  • film-forming, skin-conditioning, mild moisturising, support for product texture.

• These cosmetic grades are usually more purified and tailored than standard food fish protein powders, but originate from similar raw materials (e.g., fish skins, scales).

Conclusion

Fish protein as a food ingredient offers high-quality complete protein with useful functional properties (gelation, emulsification, water/fat binding, solubility) and a favourable essential amino acid profile. When properly processed and protected from oxidation, it can be used to fortify foods, design high-protein products, and valorise fish by-products, contributing to both nutritional value and sustainability. Strict attention to raw material quality, contaminants, allergen labelling and GMP/HACCP is essential to ensure safe, stable and sensorially acceptable products.

Mini-glossary

• SFA/MUFA/PUFA – saturated / monounsaturated / polyunsaturated fatty acids; fish lipids typically contain relatively more PUFA (especially n-3) than terrestrial animal fats, with modest SFA and MUFA.

• EPA/DHA – eicosapentaenoic acid / docosahexaenoic acid, long-chain marine n-3 fatty acids associated with heart, brain and vision benefits when consumed in sufficient amounts as part of the diet.

• BV (biological value) – indicator of how efficiently dietary protein is used for body protein synthesis; fish protein generally has high BV due to its complete amino acid profile.

• FPC/FPI/FPH – fish protein concentrate / fish protein isolate / fish protein hydrolysate, the main technological forms of fish protein ingredients used in foods and supplements.

• GMP/HACCP – good manufacturing practices / hazard analysis and critical control points; structured systems to guarantee safe, hygienic and traceable production.

• BOD/COD – biochemical / chemical oxygen demand; measures of organic load in processing wastewater, important for designing and operating treatment plants and managing environmental impact.

References__________________________________________________________________________

U G Y, Bhat I, Karunasagar I, B S M. Antihypertensive activity of fish protein hydrolysates and its peptides. Crit Rev Food Sci Nutr. 2019;59(15):2363-2374. doi: 10.1080/10408398.2018.1452182. 

Abstract. The rising interest to utilize nutritionally exorbitant fish proteins has instigated research activities in fish waste utilization. The development of newer technologies to utilize fish waste has fostered use of bioactive value-added products for specific health benefits. Enzymatically obtained Fish Protein Hydrolysate (FPH) is a rich source of biologically active peptides possessing anti-oxidant, anticancer, antimicrobial and anti-hypertensive activity. Isolating natural remedies to combat alarming negative consequences of synthetic drugs has been the new trend in current research promoting identification of antihypertensive peptides from FPH. In this review, we aim to culminate data available to produce antihypertensive peptides from FPH, its composition and potential to be used as a therapeutic agent. These purified peptides are known to be rich in arginine, valine and leucine. Reports reveal peptides with low molecular weight (<1 kDa) and shorter chain length (<20 amino acids) exhibited higher antihypertensive activity. As these peptides have proven Angiotensin Converting Enzyme - I inhibitory activity in vitro and in vivo, their potential to be used as antihypertensive drugs is outrageous. However, current focus on research in the field of molecular docking is necessary to have improved understanding of interaction of the peptides with the enzyme.

Shekoohi N, Carson BP, Fitzgerald RJ. Antioxidative, Glucose Management, and Muscle Protein Synthesis Properties of Fish Protein Hydrolysates and Peptides. J Agric Food Chem. 2024 Oct 2;72(39):21301-21317. doi: 10.1021/acs.jafc.4c02920. 

Abstract. The marine environment is an excellent source for many physiologically active compounds due to its extensive biodiversity. Among these, fish proteins stand out for their unique qualities, making them valuable in a variety of applications due to their diverse compositional and functional properties. Utilizing fish and fish coproducts for the production of protein hydrolysates and bioactive peptides not only enhances their economic value but also reduces their potential environmental harm, if left unutilized. Fish protein hydrolysates (FPHs), known for their excellent nutritional value, favorable amino acid profiles, and beneficial biological activities, have generated significant interest for their potential health benefits. These hydrolysates contain bioactive peptides which are peptide sequences known for their beneficial physiological effects. These biologically active peptides play a role in metabolic regulation/modulation and are increasingly seen as promising ingredients in functional foods, nutraceuticals and pharmaceuticals, with potential to improve human health and prevent disease. This review aims to summarize the current in vitro, cell model (in situ) and in vivo research on the antioxidant, glycaemic management and muscle health enhancement properties of FPHs and their peptides.

Liu D, Ren Y, Zhong S, Xu B. New Insight into Utilization of Fish By-Product Proteins and Their Skin Health Promoting Effects. Mar Drugs. 2024 May 9;22(5):215. doi: 10.3390/md22050215.

Abstract. In regions reliant on fisheries for livelihoods, a significant number of fish by-products are generated annually due to processing. These discarded parts contain valuable biological resources, such as proteins, fish oils, and trace elements, thus holding enormous potential for reutilization. In recent years, fish by-product proteins have been widely utilized in skincare products due to their rich collagen content, biosafety, and biocompatibility. This review summarizes the research into and applications of fish by-product proteins in skin health, including alleviating oxidative stress and skin inflammation, reducing DNA damage, mitigating melanin production, improving skin hydration, slowing skin matrix degradation, and promoting synthesis. Additionally, the possibility of improving skin health by improving the abundance of gut microbiota is also discussed. This review underscores the importance of fish by-product proteins in the fisheries, food processing, cosmetics, and biomedical industries.

Mizushige T, Komiya M, Onda M, Uchida K, Hayamizu K, Kabuyama Y. Fish protein hydrolysate exhibits anti-obesity activity and reduces hypothalamic neuropeptide Y and agouti-related protein mRNA expressions in rats. Biomed Res. 2017;38(6):351-357. doi: 10.2220/biomedres.38.351. 

Abstract. Fish protein is a source of animal protein that is consumed worldwide. Although it has been reported that the intake of Alaska pollack protein (APP) reduces body fat accumulation and increases muscle weight in rats, the mechanisms underlying these effects are poorly understood. As a possibility, peptides released from APP in the gastrointestinal tract are important to the functions of APP. In the present study, we examined the effects of APP hydrolysate digested artificially with pepsin and pancreatin on white adipose tissue and skeletal muscle. We found that APP hydrolysate group shows significantly lower weight of white adipose tissue and higher weight of soleus muscle than the control group. We also found that APP hydrolysate group reduces food intake and mRNA expressions of neuropeptide Y and agouti-related protein in the hypothalamus compared with the control group. These results may imply that APP hydrolysate exhibits anti-obesity activity by the reduction of appetite and the enhancement of basal energy expenditure by skeletal muscle hypertrophy in rats. The downregulation of orexigenic gene by APP hydrolysate in the hypothalamus may contribute to the reduction of appetite. These results suggest that the effect of APP on anti-obesity and muscle hypertrophy may be induced by peptides released from APP in the gastrointestinal tract.

Werner T, Kumar R, Horvath I, Scheers N, Wittung-Stafshede P. Abundant fish protein inhibits α-synuclein amyloid formation. Sci Rep. 2018 Apr 3;8(1):5465. doi: 10.1038/s41598-018-23850-0. 

Abstract. The most common allergen in fish, the highly-abundant protein β-parvalbumin, forms amyloid structures as a way to avoid gastrointestinal degradation and transit to the blood. In humans, the same amyloid structures are mostly associated with neurodegenerative disorders such as Alzheimer's and Parkinson's. We here assessed a putative connection between these amyloids using recombinant Atlantic cod β-parvalbumin and the key amyloidogenic protein in Parkinson's disease, α-synuclein. Using a set of in vitro biophysical methods, we discovered that β-parvalbumin readily inhibits amyloid formation of α-synuclein. The underlying mechanism was found to involve α-synuclein binding to the surface of β-parvalbumin amyloid fibers. In addition to being a new amyloid inhibition mechanism, the data suggest that health benefits of fish may be explained in part by cross-reaction of β-parvalbumin with human amyloidogenic proteins.