Pullulan.

Pullulan film has low oxygen permeability and low residual moisture transfer, and both oxygen and moisture drive loss of viable probiotic cells. That is the practical reason pullulan shells are chosen for live-culture fills.

Long-chain omega-3 fatty acids oxidise readily on exposure to oxygen. The low oxygen transmission of pullulan makes it a suitable shell for marine oil fills where a more permeable material would allow peroxide build-up.

Retinyl esters degrade on exposure to oxygen and light. A shell material with low oxygen permeability limits one of the two routes by which the fill loses potency.

Pullulan forms clear, low-oxygen-permeability films and is used as a wall material for spray-dried and nanoparticle encapsulation of poorly water-soluble polyphenols such as curcumin. The polymer carries the payload and protects it from oxygen. It does not change the polyphenol's own chemistry. Any dissolution benefit depends on the specific encapsulation process, not on pullulan being present.

Pullulan films have notably low oxygen permeability, which is the reason the polymer is chosen for shells around oxidation-sensitive lipophilic actives such as ubiquinone. The protection is physical exclusion of oxygen, not antioxidant chemistry. Shelf-life gains depend on the whole pack including the blister or bottle, not the shell alone.

Carotenoids degrade through oxidation and light exposure, and a low-oxygen-permeability shell limits one of those routes. Pullulan capsules are used where a plant-based shell with that barrier property is wanted. The pigment's own bioavailability still depends on the oil vehicle inside.

Long-chain omega-3 oils oxidise readily, so shells are selected partly for oxygen barrier. Pullulan gives that barrier in a non-animal shell, which matters for products avoiding bovine or porcine gelatin. Water activity of the fill still governs shell integrity over time.

Pullulan is the standard film former in dissolving oral strips because it makes a clear, flexible, quick-hydrating film at low thickness. Low-dose actives such as melatonin suit that format since the whole dose fits in a thin strip. The film changes where dissolution starts, not how the active behaves once absorbed.

Pullulan films are used to entrap volatile flavour and aroma oils in breath strips and coatings, holding them until the film hydrates. The polymer's low oxygen permeability also slows oxidative change in the oil. Loading is limited by how much oil the film will hold without losing mechanical strength.

Pullulan and pullulan-alginate matrices are studied as encapsulation walls for live organisms because they exclude oxygen and can be dried without harsh conditions. Survival during storage still depends mainly on water activity and temperature. Presence of the polymer alone does not establish a viability benefit for a given strain.

Enzyme powders lose activity when they pick up moisture, and pullulan shells hold less free water than gelatin, which is one reason they are chosen for such fills. The shell does not protect against gastric acid, so enteric coating or acid-stable enzymes are still needed. This is a compatibility relationship, not an activity one.

Hygroscopic fills such as choline bitartrate draw water out of the surrounding shell, and pullulan shells become brittle as they dry below their working moisture range. The result is cracking or leaking over shelf life. Formulators handle it with desiccation control and moisture-barrier packaging rather than by changing the active.

Both are microbially produced polysaccharides used in film and coating systems, and blends are studied for mechanical and barrier properties. Their functional roles differ: pullulan supplies film continuity, beta-glucan supplies structure. The pairing is materials science, and neither is an active in that context.

Pullulan is only partly digested by human enzymes because the alpha-1,6 linkages between maltotriose units resist pancreatic amylase, so a fraction reaches colonic bacteria. Combined with an established prebiotic such as inulin the total fermentable load goes up. At capsule-shell quantities the amount involved is far too small to matter physiologically.