Creating Smoother Frozen Treats
Imagine a world where your ice cream never forms those gritty ice crystals in your freezer and boasts a perfectly creamy texture, all thanks to an unexpected hero: fish.
This isn't a scene from a science fiction movie but the reality of modern food science. Researchers and corporations are harnessing the power of proteins from fish to revolutionize the frozen dessert industry. From genetically modified antifreeze proteins that keep ice cream smooth to sustainable waste-reducing solutions from fish skin, this innovative crossover is making waves in how we create and enjoy one of the world's most beloved treats 1 2 .
To understand why fish proteins are so valuable, you first need to know about ice crystals. When ice cream temperature fluctuates in the freezer, small ice crystals melt and re-freeze into larger, gritty ones, a process known as recrystallization. This is what gives old ice cream a sandy, unpleasant texture. Fish that live in freezing polar waters, like the ocean pout, produce natural antifreeze proteins to survive 1 4 .
These special proteins work by binding to the surface of ice crystals, inhibiting their growth and preventing them from getting larger. For ice cream manufacturers, this is the holy grail. Incorporating these proteins means:
Antifreeze proteins from fish can prevent ice crystal growth at concentrations as low as 0.1% of the ice cream mixture.
While the protein originates in fish, the version used in products like Unilever's ice cream is not directly extracted from them. Instead, the gene responsible for producing the antifreeze protein in the ocean pout is inserted into genetically modified baker's yeast 1 4 . This yeast then ferments and produces the desired protein, which is later purified and added to the ice cream mix. This method ensures a scalable and efficient production process.
Antifreeze proteins (AFPs) adsorb to the surface of ice crystals through hydrogen bonding, creating a curved surface that prevents further crystal growth.
AFPs bind to ice crystal surfaces
Bound proteins create curved surfaces
Curvature prevents further crystal growth
While the GM approach is revolutionary, other scientists are exploring sustainable alternatives. A 2025 study investigated using gelatin hydrolysate derived from fish skin waste—a byproduct of the fishing industry—as a natural stabilizer and emulsifier in ice cream 2 3 .
The research team followed a meticulous process to test their hypothesis:
Gelatin hydrolysate was obtained from fish skin through a process of extraction and enzymatic breakdown, making it suitable for food use.
The researchers created five different ice cream mixes, each with a different combination of stabilizers and emulsifiers.
The team then analyzed each sample for its protein content, overrun (air incorporation), melting resistance, hardness, stickiness, and sensory properties.
The experiment yielded compelling data, showing that the fish skin gelatin hydrolysate was a viable functional ingredient.
The table below shows how different formulations affected key physical properties of the ice cream:
| Sample | Formulation | Protein Content (g/100g) | Overrun (%) | Key Finding |
|---|---|---|---|---|
| D1 | Sahlep + Mono-diglyceride (Control) | 3.13 | 11.44 | Baseline for comparison |
| D2 | Mono-diglyceride + Gelatin Hydrolysate | 3.75 | 9.55 | Lower overrun, higher protein |
| D3 | Sahlep + Gelatin Hydrolysate | 3.32 | 21.74 | Highest air incorporation |
| D4 | Gelatin Hydrolysate only | 3.99 | 15.79 | Highest protein content |
| D5 | Blend of all three | 3.38 | 19.16 | Balanced performance |
The data shows that gelatin hydrolysate significantly increased the protein content of the ice cream, with sample D4 having the highest level 2 3 . Furthermore, certain combinations, like D3, dramatically improved the overrun, which is crucial for a light and creamy texture 2 3 . The study also found that the hydrolysate helped slow down the melting rate and improved the ice cream's resistance to collapsing 2 3 .
From a sensory perspective, the study concluded that the ice creams containing the fish skin ingredient were acceptable, with no significant negative impacts on appearance, flavor, or taste reported in the initial evaluation 2 .
The following table compares the two primary fish-based approaches to improving ice cream:
| Feature | GM Antifreeze Protein | Fish Skin Gelatin Hydrolysate |
|---|---|---|
| Source | Gene from ocean pout, produced by GM yeast | Hydrolysate from fish processing waste (skin) |
| Primary Function | Inhibits ice crystal growth (anti-recrystallization) | Acts as a stabilizer and emulsifier |
| Main Benefit | Unparalleled texture stability in low-fat products | Upcycling waste; improving melt resistance and overrun |
| Regulatory Status | Approved in US, Australia; debated in Europe 1 4 | Considered a natural ingredient, though sensory effects must be managed 2 |
| Consumer Perception | Faces scrutiny due to "GM" label 4 | May be perceived as more "natural" and sustainable |
Comparison of protein content across different ice cream formulations
Creating the next generation of frozen desserts requires a suite of specialized ingredients. Below is a table of key reagents and their functions, as seen in the research.
| Reagent / Material | Function in Ice Cream Research |
|---|---|
| Ice Structuring Protein (ISP) | Genetically engineered protein used to inhibit ice crystal growth, providing superior texture and stability 1 4 |
| Gelatin Hydrolysate (Fish Skin) | A natural stabilizer and emulsifier derived from fish waste; improves protein content, overrun, and melting properties 2 3 |
| Sahlep | A traditional stabilizer from orchid roots; increases viscosity and helps achieve a smooth consistency 2 3 |
| Mono-diglycerides | A common emulsifier that helps create a uniform structure by dispersing fat molecules evenly 2 |
| Fish Protein (FP) Powder | Used for nutritional fortification; can improve protein content but may introduce "fishy" off-flavors over time |
The use of GM-derived ingredients, especially from fish, is not without debate. When Unilever sought approval for its ice-structuring protein in Europe, a group of scientists raised concerns. They argued that the protein produced by yeast might have a slightly different structure (glycosylation pattern) than the one found naturally in the fish, potentially making it a "unique antigen" that could cause allergic reactions or inflammation 4 .
"The protein produced by yeast might have a slightly different structure than the one found naturally in the fish, potentially making it a 'unique antigen' that could cause allergic reactions or inflammation."
They called for more comprehensive, long-term safety studies before the ingredient was approved for the European public 4 . This highlights the ongoing tension between rapid food tech innovation and the precautionary principle favored by some consumer groups and regulators. In Europe, products containing this GM protein do not have to be labeled as "genetically modified" because the processing aids (the yeast) are removed, and the final protein is considered identical to a natural one—a point contested by critics 1 4 .
The journey of fish-protein ice cream from lab to supermarket is still unfolding. The potential is vast: reducing food waste by using fish skin, creating healthier low-fat options with better texture, and pushing the boundaries of food science. However, challenges remain. Beyond the GM debate, sensory studies on fish-fortified ice cream show that undesirable "fishy" flavors and odors can develop after about two months of storage, indicating a need for further research to stabilize these products .
Ultimately, the success of such innovative foods will hinge on a combination of solid science, transparent communication, and consumer willingness to embrace new ideas. The next time you enjoy an exceptionally smooth scoop of ice cream, you might just have a cold-water fish to thank.
This article was synthesized from scientific studies and news reports published in Nature Biotechnology, Food Navigator, and the MDPI journal Gels.