Pullulan

Pullulan is a natural polysaccharide produced by the fermentation of the yeast-like fungus Aureobasidium pullulans on glucose or starch substrates. It is a linear polymer of maltotriose units linked by alpha-1,6-glycosidic bonds, which gives it a uniquely flexible and film-forming structure. In food, pullulan is used primarily as a film-forming agent for edible capsules, supplement coatings, and thin edible films used in breath-freshening strips and instant beverage pods. Its ability to form transparent, oxygen-impermeable, water-soluble films makes it well suited for these applications.

JECFA evaluated pullulan in 2006 and classified the ADI as "not specified," reflecting the evidence that pullulan is essentially non-digestible by humans (no human enzyme cleaves the alpha-1,6-glycosidic bond efficiently), passes through the gastrointestinal tract largely intact, and is fermented by colonic microbiota to short-chain fatty acids. No systemic absorption of intact pullulan has been demonstrated, and toxicological studies showed no adverse effects at high dietary levels. Its fermentation behaviour in the colon is similar to other prebiotic fibres.

Pullulan is approved in the EU as E1204 for use in specific food applications including supplement capsule shells and edible film applications. In Japan and other Asian markets, pullulan has a longer history of use and is used in a broader range of food applications as a coating and film agent. The growth of plant-based and vegan supplement capsules has increased interest in pullulan as an alternative to gelatin (which is animal-derived). Pullulan capsules are marketed as suitable for vegetarians and vegans and are certified halal. No adverse effects have been identified at typical dietary exposure levels from supplement capsule use.