Polydextrose
What it does
Bulking agent; soluble fibre.
How it's made
Synthesised from glucose.
Polydextrose is a bulking agent used to add body and texture to reduced-sugar and reduced-fat foods without adding much energy. It is a form of soluble fibre, so it fills the physical role that sugar or fat would play in a recipe while contributing few calories and acting as a prebiotic in the gut.
It is made synthetically by heating and combining glucose (dextrose) with small amounts of sorbitol and an acid catalyst such as citric acid. Under heat and reduced pressure, the glucose molecules link together in a highly branched, random way, building up large fibre-like polymer chains rather than the simple, digestible chains found in starch.
Because the links are branched and irregular, the body's enzymes cannot fully break them down, which is why polydextrose behaves as fibre and yields little energy. The finished material is purified, sometimes neutralised, and dried into a white powder used in baked goods, confectionery and low-calorie products.
Possible reactions
Laxative effect in larger amounts.