Microencapsulation is not about the pill you swallow. It happens at a scale a thousand times smaller: each individual bacterium is wrapped in its own protective coat, so it survives the stomach and is released only where it can do its job.
The short version
- A single bacterium is about 2 microns long, roughly 35 times thinner than a human hair. Microencapsulation wraps each one, individually, in a food-grade polymer coat.
- The coat stays sealed in stomach acid and dissolves in the gentler conditions of the small intestine, so the bacteria are released alive, exactly where they work.
- The coat is formed in supercritical carbon dioxide at 40 °C, with no water, no solvents and no high heat, so the bacteria are never harmed during the process.
- The same shield keeps moisture and oxygen out on the shelf, which is why Velobiotics™ stays potent at room temperature.
Most probiotics never arrive
A probiotic only helps you if it reaches your intestine alive. That is a long journey for a living cell. On the shelf it faces heat, oxygen and humidity. In your body it faces stomach acid at pH 1 to 2, strong enough to dissolve most bacteria within minutes.
Labels talk about billions of cultures. What matters is how many billions are still alive when they get to the place where they can actually work. For most ordinary probiotics, that number is a small fraction of what went into the bottle.
An unprotected probiotic
- Slowly dies on the shelf, faster in heat and humidity
- Dissolves in stomach acid before reaching the intestine
- Often needs refrigeration to slow the losses
- The "billions" on the label are counted at manufacture, not at arrival
A micro-shielded Velobiotics™ probiotic
- Each bacterium is sealed in its own moisture- and oxygen-resistant coat
- The coat stays closed in acid and opens in the intestine
- Stable at room temperature, proven at 30 °C for 12 weeks
- More live bacteria delivered where they can colonise and work
Armour for a single cell, not for the pill
When people hear "capsule" they picture the pill. Microencapsulation works at a completely different scale. A bacterium is about two microns long. A human hair is around seventy microns wide. Microencapsulation wraps each individual bacterium in a coat a fraction of a micron thick, made of two food-grade polymers that bond to each other.
Think of it as giving every soldier their own armour, rather than putting the whole army in one tent. If the tent tears, everyone is exposed. If each cell has its own shield, the protection travels with it all the way to the intestine.
A shield that knows where it is
The two polymers in the Velobiotics™ shield were chosen because of how they behave in acid. In the stomach the coat barely swells, so almost nothing gets out and the acid stays out. When the shielded bacteria move into the small intestine, where the pH rises to around 6.8, the coat swells, dissolves and releases its passenger.
Researchers at the CSIR tested this using a marker compound sealed in the same polymer matrix. In stomach-strength acid, less than 5% escaped in 24 hours. In intestinal conditions, about half was released in three hours and 85% within a day. The small intestine is exactly where probiotics need to be released, and three hours is roughly how long food spends there.
Bonded in carbon dioxide, never touched by water or heat
Most ways of coating bacteria involve water, organic solvents or heat. All three damage living cells. Water is the worst: it wakes dormant bacteria, which then burn through their food and die. The Velobiotics™ process avoids all three.
Instead it uses supercritical carbon dioxide: ordinary CO₂ pressed to about 300 bar at just 40 °C, where it behaves like a liquid and a gas at the same time. In that state it softens the two polymers so they can bond around the bacteria. When the pressure is released, the CO₂ simply flashes back to gas and leaves behind a dry, free-flowing powder of shielded cells. No residue, no solvent, no water.
Two food-grade polymers and the freeze-dried probiotic are loaded into a sterile high-pressure vessel.
Supercritical CO₂ at about 300 bar and 40 °C softens the polymers without heat or solvent.
The polymers form an interpolymer complex, a hydrogen-bonded mesh, around each bacterium.
The mixture is sprayed into a chamber; the CO₂ evaporates instantly, leaving a dry shielded powder.
“The technology avoids exposure of the active to water, solvents, heat or oxygen during the encapsulation process.”
— Moolman, Labuschagne, Thantsha, van der Merwe, Rolfes & Cloete, South African Journal of Science, 2006
The same shield keeps the shelf life
Because the two polymers bond to each other, the finished coat holds far less water than the same polymers simply mixed together. In the CSIR tests it absorbed about 30% less moisture in humid conditions. Less moisture means the bacteria stay dormant and alive for longer, which is why Velobiotics™ does not need a fridge. We cover that evidence on the heat stability and shelf-life page.
The science in detail
The materials, the process and the numbers behind the story above, for readers who want them.
Which polymers are used, and why those two?
The shield is an interpolymer complex of poly(vinyl pyrrolidone) (PVP) and poly(vinyl acetate-co-crotonic acid) (PVAc-CA). Both are approved for pharmaceutical use, both can be softened by supercritical CO₂, and both are water-swellable. Together they hydrogen-bond into a network that is less soluble than either polymer alone.
The crotonic-acid groups on PVAc-CA are the pH switch: at low pH they stay un-ionised and the matrix barely swells; above roughly pH 5 they ionise, the network swells and releases. That is the mechanism behind the release curve in Figure 2. Glyceryl monostearate (GMS), an acid-stable, digestible lipid, can be added as an extra moisture and oxygen barrier; the 2009 study showed it further improved protection.
What exactly is supercritical CO₂?
Above 31.1 °C and 73.8 bar, carbon dioxide stops having a separate liquid and gas phase. This "supercritical" fluid is dense like a liquid but flows like a gas, and it dissolves into polymers, lowering their glass-transition temperature so they become workable at low temperature. The process used for Velobiotics™ is a form of PGSS (Particles from Gas-Saturated Solutions): the polymer/CO₂/probiotic slurry is expanded through a nozzle, the CO₂ evaporates and the polymers freeze into particles around the bacteria. Free bacteria exposed to 300 bar and 40 °C for two hours showed the same counts as unexposed controls, immediately and after six weeks of storage.
How was the release behaviour measured?
The CSIR team pressed 6 mm tablets of the polymer matrix containing indomethacin, a well-characterised marker drug, and ran a standard dissolution test: four tablets in pH 1.2 buffer and eight in pH 6.85 buffer at 37 °C, measuring concentration by UV spectroscopy. Results: under 5% release at pH 1.2 in 24 hours; about 50% at 3 hours and 85% at 24 hours at pH 6.85, with minimal burst release. Scanning electron microscopy then showed shielded B. longum being released from the matrix after suspension at pH 6.8.
Where does the "1000× more" promise come from?
Two separately published effects multiply. First, survival through simulated digestion: encapsulated bacteria showed an average improvement of 1.6 to 1.8 log units (about 40 to 65 times more survivors) than unprotected bacteria. Second, survival in storage: after 12 weeks at 30 °C, encapsulated B. longum retained 6 log (a million times) more live cells than unprotected cells, and B. lactis 3.3 log (about 2,000 times) more. In real life a probiotic must survive both the shelf and the stomach, so the effects compound. "1000× more live probiotics to your gut" is our conservative summary of that combined, published benefit.
References
- Moolman FS, Labuschagne PW, Thantsha MS, van der Merwe TL, Rolfes H, Cloete TE. Encapsulating probiotics with an interpolymer complex in supercritical carbon dioxide. South African Journal of Science 2006;102:349–354. PDF
- Thantsha MS, Cloete TE, Moolman FS, Labuschagne PW. Supercritical carbon dioxide interpolymer complexes improve survival of B. longum Bb-46 in simulated gastrointestinal fluids. International Journal of Food Microbiology 2009;129:88–92. PDF
- Thantsha MS, Labuschagne PW, Mamvura CI. Supercritical CO₂ interpolymer complex encapsulation improves heat stability of probiotic bifidobacteria. World Journal of Microbiology and Biotechnology 2014;30:479–486. PDF
The rest of the science, in order
Seven short pages. Start anywhere; each one stands on its own.
A father, a hospital bed, and the question that started everything.
View →2Why most probiotics failHeat, humidity, acid and bile: the five challenges a probiotic must survive.
View →4Surviving stomach acidPeer-reviewed: 40 to 65 times more live bacteria make it through.
View →5Heat stability & shelf lifeStays potent at 30 °C for up to 12 weeks. No fridge needed.
View →6The published researchThree peer-reviewed papers from CSIR and the University of Pretoria, explained.
View →7About VelobioticsThe team turning South African science into probiotics that work.
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