How Is Marine Collagen Made? From Fish to Supplement

Marine collagen is made by chemically and enzymatically stripping collagen protein from fish waste, primarily skins, scales, and bones, then breaking that protein into small peptides and drying it into a powder. The journey from a fish processing plant’s discard bin to a jar of supplement powder involves at least half a dozen distinct steps, each of which shapes the final product’s purity, taste, peptide size, and how well your body can absorb it. The process is more industrial chemistry than kitchen science, and the details matter more than most supplement labels let on.

Where the Raw Material Comes From

Marine collagen starts as leftovers. When fish are filleted for the food industry, roughly half the animal by weight becomes waste: skins, scales, bones, fins, and swim bladders. These byproducts are rich in type I collagen, the same structural protein that makes up most of your own skin and connective tissue. Manufacturers source these materials from a wide range of species. Researchers have successfully isolated collagen from the scales of lizard fish, horse mackerel, grey mullet, flying fish, and yellowback seabream, among others, confirming that the extracted collagen is type I and composed of the expected protein chains.¹ Tilapia skin, cod skin, and snapper skin are also widely used at commercial scale.

The appeal of using fish waste is both economic and environmental. These discards are cheap and abundant, and turning them into high-value collagen products diverts material from landfills and renders it useful, fitting neatly into what sustainability researchers call a circular bioeconomy.² In practice, the species and tissue used depend on regional fishing industries. A manufacturer in Southeast Asia might rely on tilapia skins; one in Northern Europe might use cod. The fish’s habitat temperature turns out to matter quite a bit for the collagen’s properties, a point we’ll return to later.

Preparing Fish Skins and Scales

Raw fish parts can’t go straight into an extraction tank. Scales are heavily mineralized with calcium compounds that have to be removed first, a step called demineralization. Skins need to be cleaned of residual fat, pigment, and non-collagen proteins. Both steps typically happen in cold acid or chelating solutions.

For scales, the standard approach involves soaking them in dilute hydrochloric acid or EDTA (a chelating agent that grabs onto calcium ions and pulls them out of the matrix). Research on carp scales found that soaking in about 1 molar hydrochloric acid for around 95 minutes at optimized conditions removed over 92% of the mineral content without destroying the collagen underneath.³ EDTA-based treatments can also achieve thorough demineralization, though they tend to take longer, with studies showing maximum mineral removal after about 48 hours of soaking.⁴

Temperature control during this stage is critical. Processing is kept at or below 4°C to prevent the collagen from starting to unravel, which would degrade the protein before extraction even begins.⁵ Essentially, the entire early phase of production happens in a cold room. It’s slow, deliberate work aimed at peeling away everything that isn’t collagen while keeping the collagen intact.

Extracting the Collagen

Once the raw material is cleaned and demineralized, the collagen itself has to be dissolved out. There are two main approaches, and most commercial production uses one or both.

The first is acid extraction. The cleaned skins or scales are soaked in a dilute acid, usually acetic acid (essentially vinegar at a controlled concentration), which swells the tissue and dissolves the collagen into solution. The product is called acid-soluble collagen, or ASC. Yields from this method are modest. From fish scales, ASC yields range from roughly 0.4% to 1.5% of the dry weight depending on species.¹ Skin generally yields more than scales because it has fewer minerals and more accessible collagen fibers.

The second approach adds an enzyme, usually pepsin, to the acid solution. Pepsin is a digestive enzyme that selectively clips the short non-helical ends of collagen molecules (called telopeptides) without damaging the long triple-helix structure that gives collagen its biological usefulness.⁶ This clipping breaks cross-links between collagen molecules, making more collagen soluble and boosting yields substantially. Pepsin-solubilized collagen (PSC) from bighead carp fins, scales, skins, bones, and swim bladders has been confirmed to retain its triple-helical structure, meaning the collagen is still functionally intact despite the enzymatic treatment.⁷ Independent analysis of Nile tilapia skin collagen confirmed the same: both acid-extracted and pepsin-extracted collagen retained their native, undenatured triple-helix form.⁸

At this stage the product is still whole collagen, large intact protein molecules dissolved in solution. That’s the starting point for supplements, but it isn’t the finished product yet. Whole collagen molecules are too big for your gut to absorb efficiently, which is why the next step exists.

Hydrolysis Turns Collagen Into Peptides

To make the collagen useful as a supplement, manufacturers break the large protein chains into much smaller fragments called collagen peptides or collagen hydrolysate. This is done through further enzymatic treatment, typically using food-grade proteases that chop the long collagen chains into pieces small enough to dissolve easily in water and pass through your intestinal lining.

The goal is to produce peptides with a molecular weight mostly below about 5,000 daltons, with a large fraction under 1,000 daltons. These small fragments are highly soluble and have much better bioavailability than intact collagen. This hydrolysis step is what distinguishes “collagen peptides” or “hydrolyzed collagen” (the form sold in most supplements) from “collagen” or “gelatin,” which are less processed and harder to absorb.

The specific enzymes, temperatures, and durations used during hydrolysis determine the peptide size distribution and which bioactive sequences end up in the final product. This is where manufacturers have room to fine-tune. Different enzyme combinations produce different peptide profiles, which can influence everything from taste to potential biological activity.

Getting Rid of the Fishy Smell

One of the biggest practical challenges in marine collagen production is odor. Fish-derived collagen hydrolysates can carry a persistent fishy smell and bitter taste from volatile compounds generated during processing. If you’ve ever opened a marine collagen powder and caught a whiff of the ocean, you’ve encountered this issue firsthand.

Manufacturers use several deodorization techniques. Activated carbon adsorption is one of the most reliable. Research on tiger puffer skin gelatin found that powdered activated carbon filtration reduced fishy odor without compromising the gelatin’s physical or functional properties, outperforming other deodorization methods tested.⁹ Ultrafiltration, which pushes the solution through a membrane with very fine pores, is another option. When scallop hydrolysate was treated with ultrafiltration using a polysulfone hollow fiber membrane, protein recovery reached 92% and bitterness was significantly reduced.¹⁰

The choice of deodorization method has trade-offs. Activated carbon is cheap and effective but can absorb some of the collagen along with the odor compounds. Ultrafiltration preserves more protein but requires expensive equipment. Most commercial products undergo some form of odor removal, which is one reason marine collagen powders today smell much milder than products from a decade ago.

Drying Into Powder

After purification, the liquid collagen hydrolysate needs to become the dry powder you scoop into your coffee or swallow in a capsule. Two drying methods dominate: spray drying and freeze drying.

Spray drying shoots the liquid through a nozzle into a hot chamber, instantly evaporating the water and producing fine spherical particles. It’s fast, continuous, and cost-effective at scale. Freeze drying, on the other hand, freezes the solution first and then removes water under vacuum, producing irregular glass-shard-like fragments.¹¹ Freeze drying tends to yield a higher proportion of the amino acids proline and hydroxyproline (the signature building blocks of collagen), while spray-dried hydrolysate retains more volatile compounds and shows stronger antioxidant activity in some assays.

Comparisons of gelatin from fish swim bladders found that freeze drying produced the highest yield per batch, followed by vacuum drying and then spray drying, though spray-dried material had slightly better solubility and emulsifying properties.¹² In practice, supplement-grade marine collagen is most often spray dried because the equipment is cheaper to run at high volumes, and the resulting powder dissolves well in liquids.

Why the Fish Species Matters

Not all marine collagen is created equal, and the fish it comes from matters more than marketing copy usually acknowledges. The key variable is the water temperature the fish lived in, because collagen’s thermal stability tracks closely with the animal’s habitat temperature.

Warm-water fish like tilapia and eel produce collagen with higher levels of the cyclic amino acids proline and hydroxyproline. These amino acids lock the triple-helix structure into a tighter configuration, raising the temperature at which the collagen unravels (its denaturation temperature). Eel-fish skin collagen, for instance, showed denaturation temperatures of 35–39°C, approaching the stability of mammalian collagen.¹³ Cold-water fish like cod produce collagen with lower proline and hydroxyproline content and higher serine content, making their collagen less thermally stable. Researchers found a strong positive correlation between a fish’s physiological temperature and its collagen’s thermal stability.¹⁴

For supplements, this mostly matters during manufacturing: collagen from cold-water fish denatures at lower temperatures, so processing has to be even more carefully temperature-controlled to avoid degrading the product. Once the collagen is fully hydrolyzed into small peptides, thermal stability becomes less of a concern because the triple helix is already broken down. But for biomedical or cosmetic applications where intact collagen structure matters, warm-water species have a clear advantage.

Newer Green Extraction Methods

The acid-and-enzyme extraction process described above works, but it generates chemical waste and can be slow. Researchers are developing greener alternatives. Deep eutectic solvents (DES), which are mixtures of simple, inexpensive compounds like choline chloride and organic acids, have shown particular promise. When researchers extracted collagen from beluga sturgeon skin using a choline chloride-acetic acid solvent combined with ultrasound treatment, they achieved extraction yields of 24%, dramatically higher than conventional acid extraction from scales.¹⁵

Ultrasound-assisted extraction, supercritical fluid extraction, and various combined approaches are also being explored.¹⁶ These techniques aim to reduce processing time, cut down on harsh chemicals, and improve yields. Most are still at the research or pilot scale, but they signal where the industry is headed. The overall challenge is bridging the gap between laboratory yields and cost-effective large-scale manufacturing.¹⁷

Safety and Heavy Metal Concerns

Fish accumulate heavy metals from seawater, so a reasonable question is whether those metals end up in your collagen supplement. They can, though the levels found so far in tested products have been reassuringly low. A risk assessment of commercially available marine collagen supplements from fish and jellyfish found arsenic as the most abundant contaminant at a mean of about 0.59 mg/kg, followed by lead at about 0.13 mg/kg, while mercury was detectable in only 12% of samples. None of the tested products exceeded EU regulatory limits, and estimated daily intake from recommended supplement doses was consistently below established safety thresholds.¹⁸

On the manufacturing side, EDTA pre-treatment, already used routinely for demineralization, doubles as a heavy-metal removal step. Researchers have also demonstrated that sulfonated polystyrene nanospheres can pull heavy metals out of collagen solutions, reducing metal ion concentrations to regulatory standards in a single treatment while preserving the collagen itself.¹⁹ These decontamination tools exist, but whether any given supplement brand uses them is a question of the manufacturer’s quality protocols, not the technology. Third-party testing certifications (NSF, USP, or equivalent) are the consumer’s main assurance that metal levels have been checked.

What Happens After You Swallow It

The entire production process, from extraction through hydrolysis and drying, is designed to deliver collagen peptides small enough to survive digestion and reach your bloodstream. Studies confirm this actually happens. In a randomized, double-blind crossover trial in healthy adults, blood levels of collagen-derived peptides rose measurably after ingesting collagen hydrolysate. The most abundant circulating peptide was Pro-Hyp (a two-amino-acid fragment of proline and hydroxyproline), followed by several other characteristic collagen fragments.²⁰

Smaller peptides appear to have an absorption advantage. Research comparing collagen tripeptides (three-amino-acid fragments) to higher-molecular-weight collagen peptides in rats found that the small tripeptides were more stable in gastrointestinal fluid and reached higher plasma levels.²¹ This is part of why manufacturers push hydrolysis as far as they do: smaller fragments don’t just dissolve better in your morning drink, they also get through the gut wall more efficiently.

Once absorbed, these peptides circulate and appear to signal skin cells to ramp up collagen production. In vitro experiments on human fibroblasts (the cells that produce collagen in your skin) have shown dose-dependent increases in both collagen and elastin synthesis when exposed to marine collagen peptides, along with a reduction in cellular aging markers.²² A review of clinical and preclinical evidence on hydrolyzed marine collagen found that oral intake supports fibroblast activation with high systemic bioavailability, and preclinical models have shown accelerated wound healing with increased collagen production in the tissue.²³ The evidence is encouraging, though, as with most supplement research, more large-scale human trials would strengthen the case.

Why Vitamin C Keeps Showing Up on the Label

If you’ve looked at marine collagen supplements, you’ve probably noticed that many include added vitamin C. This isn’t marketing filler. Vitamin C is a required cofactor for two enzymes your body uses to build and stabilize collagen: prolyl hydroxylase and lysyl hydroxylase. Without adequate vitamin C, those enzymes deactivate, collagen synthesis stalls, and at the extreme, you get scurvy.²⁴ Adding vitamin C to a collagen supplement makes biochemical sense: you’re supplying the raw peptide building blocks and the cofactor your cells need to use them. In animal models, combining marine collagen with ascorbic acid enhanced collagen fiber deposition and alignment in healing tendons.²⁵

Shelf Stability of the Finished Product

Once marine collagen has been dried and packaged, the peptides are relatively stable but not indestructible. Research tracking collagen peptide beverages during storage found that the majority of peptides (those under 1,000 daltons, which made up about 65% of the total) held steady regardless of storage temperature. However, the small fraction of higher-molecular-weight peptides (above 5,000 daltons) degraded significantly over 12 weeks at temperatures ranging from refrigerator cold to room temperature and above. Frozen storage prevented this breakdown entirely. Powder forms, with their low moisture content, are inherently more stable than ready-to-drink liquids, which is one reason powders dominate the supplement market.

Marine Collagen Beyond Supplements

The same production pipeline that feeds the supplement industry also supplies materials for biomedical research and tissue engineering. Marine collagen is water soluble, metabolically compatible, and avoids the religious and disease-transmission concerns associated with bovine or porcine collagen, making it attractive for medical use.²⁶ Researchers have built scaffolds from marine collagen, sometimes combined with other materials and cells, for applications in skin grafting, bone repair, and cartilage regeneration.²⁷ In these contexts, the extraction and purification steps are even more stringent than for food-grade supplements, because the collagen may need to retain more of its native structure and meet medical-device sterilization standards. The growing demand from both the supplement and biomedical sectors is one reason researchers continue pushing for higher-yield, lower-waste extraction technologies.