Inulin vs Resistant Dextrin

Inulin is a long-chain fructan extracted from plants, usually chicory root. Resistant dextrin is manufactured by processing starch with heat, acid or enzymes. Both dissolve clear and count as dietary fibre, but they come from different starting materials by different routes, and behave differently under heat.

The Short Answer

Inulin is extracted, largely unchanged, from a naturally fructan-rich plant. Resistant dextrin is built: ordinary starch is deliberately restructured until it resists digestion. That difference in origin shows up most clearly in how each behaves when heated with something acidic.

Where Each Comes From

Inulin is a fructose-chain fibre found naturally in chicory root, Jerusalem artichoke and a number of other plants, extracted with hot water rather than chemically transformed. Resistant dextrin starts as starch, commonly from maize, wheat, potato or tapioca, and is restructured through heat, acid and enzyme treatment into a form that resists digestion; nothing resembling resistant dextrin exists in the source plant before processing.

Solubility and Texture

Both dissolve into water with relatively little thickening, unlike gel-forming fibres like psyllium. At typical use levels, neither changes the texture of a drink noticeably.

Heat and Acidity

This is the clearest practical difference. Inulin is vulnerable specifically to heat and acidity together: stable at neutral to alkaline pH regardless of temperature, but prone to breaking down when heated in an acidic liquid. Resistant dextrin has shown stable behaviour through normal heating in research on its structure, without the same acid-sensitivity.

How Each Is Regulated as Dietary Fibre in Australia

Inulin has its own dedicated AOAC method under Schedule 11 of the Food Standards Code (999.03), reflecting its long-established status as a recognised fibre. Resistant dextrin, as a manufactured ingredient, needed FSANZ Application A491 to establish a method for measuring resistant maltodextrins specifically, a more recent and narrower regulatory pathway than inulin's.