The Slow Failure: Why High-Protein Drinks Are Gelling on the Shelf

Protein is having a moment. It is in coffee and bottled water, oat milk and snack bars, and the number on the front of the package keeps climbing: 20 grams a serving, then 30, then 40. For the companies making these beverages, the boom comes with a quiet and expensive problem, one that stays hidden until the product is already on store shelves.

A high-protein beverage can pass every check at the plant, ship out looking perfect, and then, weeks later, slowly turn to gel in the bottle. Food scientists call it age gelation. It is not the fast separation a formulator catches on the bench in a day or two, when protein drops out of a fresh sample. This one is slow. By the time anyone can see it, the beverage is in a warehouse, on a truck, or in a customer's hand, and the cost, in returns, waste, and reputation, is already mounting.

That makes it a technical puzzle for a formulator, a shelf-life risk for procurement, and a broken promise for a marketer who sold a clean label. And it is not one problem with one fix; it is five processes, running concurrently, that all end in the same place.

WHAT AGE GELATION IS

Age gelation happens during storage. For weeks or months a beverage looks fine, thickening so gradually no one notices, and then it crosses a line and sets into a soft gel. Settled sediment you can shake back in; a gel you cannot.1 Where that tipping point lands is not fixed, and one of the biggest levers is simply how hard the beverage was heated to sterilize it.2

So the question is not whether a beverage will gel; given enough time, most will. It is whether it gels inside the intended shelf life or long after, and what a company can do to push that day out.

THE FIVE CLOCKS

Several mechanisms can cause it, and usually more than one is at work. Picture five clocks ticking toward the moment the beverage gels; slow one and the other four keep going. They run in any high-protein beverage, milk or plant.

1. Enzymes that survive the heat.

Some enzymes act like tiny scissors, and a few outlast the heat that sterilizes a beverage. Sealed in the bottle, they keep cutting the protein apart. This is one of dairy's biggest clocks: plasmin comes from the milk itself,3 and AprX is left behind by bacteria that grew in the raw milk before processing, working long after the bacteria are gone.4 Milk protein floats in tiny bundles, casein micelles, kept apart by a fuzzy coat like the fuzz on a tennis ball. The enzymes shave the coat away, the bundles clump, and the clumps build the network that sets, with early signs measurable before any gel appears.5

Plant proteins are mostly spared: pea, soy, and fava carry no plasmin and none of that bacterial enzyme, so for them this clock stays mostly quiet.

2. Proteins that clump on their own.

Even without enzymes, heat makes proteins misbehave. In milk, a whey protein sticks to those bundles, then peels off in storage and links up with others into a web that thickens the liquid.1 Plant proteins get there faster: a plant protein is a seed's storage packet, built to sit tightly packed in a bean, and it barely solubilizes.6 Heat makes it unfold and clump, so a plant-based beverage starts out closer to gelling, which is why so much work goes into keeping the protein solubilizes.7 Trials with pea or fava protein show exactly this.8

3. Calcium that glues proteins together.

Calcium, the mineral on the label, acts as glue between proteins. Milk bundles hold a store of it inside, like a sponge, and over months some seeps out and pulls proteins together.9 How much is free, and how the acidity drifts, set the pace.10 Plant proteins hold no such store but are just as sensitive to the calcium in the water; it lets them bridge together, exactly how you would set a gel on purpose. Add calcium for the label, and you may be handing the gel its bridges.6

4. Slow browning.

Then there is plain chemistry. The Maillard reaction, the browning of a seared steak, creeps along inside a sealed beverage at room temperature: sugars react with proteins and form bonds that stiffen the mix and settle it out.11 How far it goes depends on the sugar.12 Plant proteins brown the same way, with a twist: a controlled dose of that browning, done on purpose before the protein goes in the bottle, is one of the better ways to keep pea protein dissolved. Endogenous glycation is both a problem and, used deliberately, part of a potential emerging solution for the cure.7

5. Sulfur bonds that chain up.

Heat exposes tiny sulfur groups on the proteins, and once exposed they link protein to protein, chaining like beads on a string. In whey beverages the chains build the longer it sits and the warmer it is stored.1314 Plant proteins do the same, and for them it is often the main cause: much of the protein in soy and pea is held together by these sulfur bonds, and heat drives them to link up.156 The best fix is upstream: a controlled pre-heat changes how the proteins behave later and steadies the finished beverage.16

Five clocks: enzymes, protein clumping, di-valent minerals, and two kinds of chemistry (glycation through maillard browning and sulfur bridging). They do not take turns; in a real beverage they overlap, which is why age gelation is so hard to blame on any one cause.

WHY MORE PROTEIN MAKES IT WORSE

Dial up the protein and all five clocks speed up at once: more protein for the enzymes to cut, more calcium in play, molecules packed close enough that any two stick. Studies of high-protein dairy beverages bear this out, and warmth speeds everything further.1718 Even a well-made product keeps changing on the shelf; the clocks never stop, they only run slower or faster.19 So the bigger the protein number on the front, the harder the shelf-life problem behind it. Concentration isn't the only starting condition that matters, how the protein was processed before it ever reached the bottle plays an important role too, since some methods leave a protein already closer to gelling than others.

WHICH CLOCK LEADS DEPENDS ON THE PROTEIN

Which clock runs fastest depends on the protein. In dairy it is usually the enzymes, the hardest cause to engineer around; in pea, soy, and fava it is the sulfur bonds, on top of a protein that starts close to gelling anyway. Blends are their own animal: mix dairy and plant protein and the two clump together into combinations neither forms alone.20 The question stays the same, but the answer is specific to the beverage, so work out which clock is loudest before reaching for a fix.

THE TOOLBOX, AND WHAT EACH TOOL CANNOT DO

There are real tools for slowing gelation, but each works on a single clock, so it is easy to aim at the wrong problem and watch the gel show up anyway.

—  Thickeners and gums (pectin, cellulose gum, guar, gellan) thicken the liquid and slow the slide toward a gel; the right one helps in acidic protein beverages, with tradeoffs in texture and taste.2122 But thickening is only traffic calming: it slows things without removing the cause, and does almost nothing about the enzymes.

—  Calcium binders like sodium hexametaphosphate mop up loose calcium.17 A real fix, but narrow: nothing for the enzymes, the sulfur bonds, or the browning, and it costs a label line and some sodium.

—  Cleaner milk goes after the enzymes at the source, keeping the bacteria from making much of the enzyme in the first place; one clever version uses lactose oxidase to hold them in check.23

—  Pre-treating the protein targets the sulfur-bond clock with a gentle, controlled cook so it cannot misbehave later.16

For a plant-based beverage there is no bacterial-enzyme problem, so the playbook is about keeping the protein dissolved: adjusting acidity, controlled browning, plant fibers, and gentler processing. No single tool covers more than a clock or two.

WHERE SEATEX FITS

Here is where our own ingredient fits. SeaTex is a seaweed-based stabilizer that works two of these clocks at once, clumping and calcium, at a low dose of 0.02 to 0.3 percent and without a separate calcium binder. Both show up in dairy and plant beverages, which is why the same ingredient earns a place in a dairy blend and a pea blend protein shakes. From a formulation perspective, application of SeaTex in products such as plant-based milks, high-protein drinks, chocolate and coffee beverages show differentiated suspension properties compared to the bench marks.   What it cannot do is switch off the enzymes behind an enzyme-driven gel; that one is a milk-quality and processing problem, not a formulation one.

WHERE TO START

If a high-protein beverage of yours thickens on the shelf, work out the cause first: the protein, the heat treatment, the storage, and the timing of the thickening each point somewhere.

Tell our technical assistant what the beverage is, how it is processed, and when the thickening starts, and we will talk through the likeliest cause, and whether the fix is in the formula or upstream in the process and/or the selection of the ingredients

[Ask our SeaTex technical assistant about your system >>https://www.marinebiologics.com/tech-support]

Marine Biologics makes SeaTex, a seaweed-based clean-label stabilizer for high-protein food and beverage. We are a small team of food scientists who spend our days on what happens to protein over a long shelf life. If you would rather talk to a person, reach out at contact@marinebiologics.com.

SOURCES

1. Raynes, J.K., Vincent, D., Zawadzki, J.L., Savin, K.W., Mertens, D., Logan, A., Williams, R. (2018). Investigation of Age Gelation in UHT Milk. Beverages 4(4):95. https://doi.org/10.3390/beverages4040095

2. Age Gelation in Direct Steam Infusion Ultra-High-Temperature Milk: Different Heat Treatments (2024). https://www.semanticscholar.org/paper/3dcbc12fedb3529a2046f4a68fc299ecb14bc29b

3. Ismail, B., Nielsen, S.S. (2010). Invited review: Plasmin protease in milk: Current knowledge and relevance to dairy industry. Journal of Dairy Science 93(11). https://doi.org/10.3168/jds.2010-3122

4. Destabilization of UHT milk by protease AprX from Pseudomonas fluorescens and plasmin (2018). https://openalex.org/W2802799032

5. D'Incecco, P., Rosi, V., Fortina, M.G., Sindaco, M., Ricci, G., Pellegrino, L. (2022). Biochemical, microbiological, and structural evaluations to early detect age gelation of milk caused by proteolytic activity of Pseudomonas fluorescens. European Food Research and Technology. https://doi.org/10.1007/s00217-022-04033-8

6. Hui, D., Liang, W., Wang, R., Feng, X., Tang, X. (2025). A Review of Gelation of Plant Proteins and Their Influencing Factors. Sustainable Food Proteins 3. https://doi.org/10.1002/sfp2.70037

7. Schneider, A.A., Bu, F., Ismail, B.P. (2023). Enhancement of pea protein solubility and thermal stability for acidic beverage applications via endogenous Maillard-induced glycation and chromatography purification. Current Research in Food Science 6:100452. https://doi.org/10.1016/j.crfs.2023.100452

8. Nawaz, M.A., Singh, T.K., Stockmann, R., Jegasothy, H., Buckow, R. (2021). Quality Attributes of Ultra-High Temperature-Treated Model Beverages Prepared with Faba Bean Protein Concentrates. Foods 10:1244. https://doi.org/10.3390/foods10061244

9. Rheological Properties of Concentrated Skim Milk: Importance of Soluble Minerals in the Changes (2003). https://openalex.org/W2028512650

10. Influence of Heating Temperature and pH on Acid Gelation of Micellar Calcium Phosphate-Adjusted Milk (2024). https://www.semanticscholar.org/paper/40406bf5226ff7e1314a966a31c8a43b8a01fe0f

11. Aguilera-Toro, M., Poulsen, N., Akkerman, M., Rauh, V., Larsen, L.B., Nielsen, S.D. (2022). Development in Maillard Reaction and Dehydroalanine Pathway Markers during Storage of UHT Milk Representing Differences in Casein Micelle Size and Sedimentation. Foods 11:1525. https://doi.org/10.3390/foods11101525

12. Maillard glycation of beta-lactoglobulin with several sugars: comparative study of the properties of the obtained polymers and of the substituted sites (2001). Lait 81. https://doi.org/10.1051/lait:2001155

13. Damodaran, S., Anand, K. (1997). Sulfhydryl-Disulfide Interchange-Induced Interparticle Protein Polymerization in Whey Protein-Stabilized Emulsions and Its Relation to Emulsion Stability. Journal of Agricultural and Food Chemistry 45:3813-3820. https://doi.org/10.1021/jf970319b

14. LaClair, C.E., Etzel, M.R. (2009). Turbidity and Protein Aggregation in Whey Protein Beverages. Journal of Food Science 74(7):C526-C535. https://doi.org/10.1111/j.1750-3841.2009.01260.x

15. Zhang, W., Jin, M., Wang, H., Cheng, S., Cao, J., Kang, D. (2024). Effect of Thermal Treatment on Gelling and Emulsifying Properties of Soy β-Conglycinin and Glycinin. Foods 13:1804. https://doi.org/10.3390/foods13121804

16. Increasing the thermal stability of high-protein beverages through the modification of whey proteins through thermal processing (2026). Journal of Dairy Science. https://doi.org/10.3168/jds.2025-27874

17. Pandalaneni, K., Bhanduriya, K., Amamcharla, J.K., Marella, C., Metzger, L.E. (2018). Influence of milk protein concentrates with modified calcium content on enteral dairy beverage formulations: Storage stability. Journal of Dairy Science 102:155-163. https://doi.org/10.3168/jds.2018-15239

18. Yun, S.-Y., Imm, J. (2021). Changes in Particle Size, Sedimentation, and Protein Microstructure of Ultra-High-Temperature Skim Milk Considering Plasmin Concentration and Storage Temperature. Molecules 26:2339. https://doi.org/10.3390/molecules26082339

19. Effects of storage time and temperature on the protein fraction of aseptic milk (2025). https://www.semanticscholar.org/paper/febd4ff3f693864c5c18c2a054b485e8b4cabcd8

20. Chihi, M., Mession, J., Sok, N., Saurel, R. (2016). Heat-Induced Soluble Protein Aggregates from Mixed Pea Globulins and β-Lactoglobulin. Journal of Agricultural and Food Chemistry 64:2780-2791. https://doi.org/10.1021/acs.jafc.6b00087

21. Hydrocolloids as thickening and gelling agents in food: a critical review (2010). https://openalex.org/W2018692029

22. Liu, J., Pedersen, H.L., Knarreborg, L., Ipsen, R., Bredie, W.L.P. (2020). Stabilization of directly acidified protein drinks by single and mixed hydrocolloids. Food Science & Nutrition 8:6433-6444. https://doi.org/10.1002/fsn3.1933

23. Rivera Flores, V.K., DeMarsh, T.A., Alcaine, S.D. (2020). Lactose oxidase: Enzymatic control of Pseudomonas to delay age gelation in UHT milk. Journal of Dairy Science 104(3):2759. https://doi.org/10.3168/jds.2020-19452