The Short Answer
Resistant dextrin is made from starch, most commonly maize, wheat, potato or tapioca depending on the manufacturer. Whichever starch it comes from, the manufacturing process (heat, acid and enzyme treatment) breaks the starch down and restructures it, and in the case of wheat-derived dextrin, this processing removes the protein fraction that contains gluten. Whether the finished ingredient can be labelled gluten free depends on testing the result, not on the plant it started as.
Same Process, Different Starch
Wheat dextrin and maize (corn) dextrin are made the same way: starch is treated with heat, acid and/or enzymes until much of it resists digestion. The difference is the starting material. Starch itself, from any source, is a carbohydrate; the gluten proteins in wheat are a separate component of the grain, largely left behind during starch extraction and further reduced by the dextrinisation process itself.
What "Gluten Free" Legally Means on an Australian Label
Schedule 4 of the Food Standards Code sets the condition for a "free" claim about gluten plainly: the food must not contain detectable gluten, oats or oat products, or cereals containing gluten that have been malted, or products of such cereals. "Detectable" means detectable by the validated test method used, not an assumption based on the ingredient's botanical origin.
Can a Wheat-Derived Ingredient Carry a Gluten Free Claim?
Yes, provided it tests as having no detectable gluten. This isn't unique to dextrin: Coeliac Australia's own guidance lists several highly refined wheat-derived ingredients, including wheat-derived glucose and dextrose, as suitable for a gluten free diet, because refining removes the gluten protein regardless of which cereal the starch came from. The same logic applies to wheat-derived dextrin: a highly processed, purified ingredient that tests clear is treated on its test result, not its starch source.
How to Check a Label
If a product carries a "gluten free" claim, it has to meet the Code's no-detectable-gluten condition regardless of which ingredients it's made from. If you want to know a specific ingredient's starch source out of personal preference rather than a gluten concern, that's a separate question the gluten free claim doesn't answer, and not every manufacturer discloses it.
Coeliac Australia's Guidance on Wheat-Derived Ingredients
Coeliac Australia maintains that certain wheat-derived ingredients, processed to remove the gluten protein, are suitable for a gluten free diet. If you have coeliac disease, this is a decision for you and your doctor or dietitian, not something to work out from a label alone: follow their guidance on any product you're unsure about.
Sources
- Australia New Zealand Food Standards Code, Schedule 4, Nutrition, Health and Related Claims (gluten free claim conditions)
- Coeliac Australia, Allergen Labelling
- FSANZ, Final Assessment Report, Application A491, Resistant Maltodextrin as Dietary Fibre